U.S. patent application number 15/980342 was filed with the patent office on 2019-11-21 for low vin high efficiency chargepump.
The applicant listed for this patent is Analog Devices Global Unlimited Company. Invention is credited to Jose Bernardo Din.
Application Number | 20190356221 15/980342 |
Document ID | / |
Family ID | 68314830 |
Filed Date | 2019-11-21 |
United States Patent
Application |
20190356221 |
Kind Code |
A1 |
Din; Jose Bernardo |
November 21, 2019 |
LOW VIN HIGH EFFICIENCY CHARGEPUMP
Abstract
A charge pump circuit comprises a first charge transfer circuit
path coupled including a first boost capacitor coupled to a first
clock input, a first charge switch coupled to a circuit input, and
a first discharge switch coupled to a circuit output; a second
charge transfer circuit path including a second boost capacitor
coupled to a second clock input, a second charge switch coupled to
the circuit input, and a second discharge switch coupled to the
circuit output; a first charge control circuit including a first
gate switch coupled to a gate input of the first charge switch, and
a first gate-drive capacitor coupled to the gate input of the
second charge switch; and a second charge control circuit including
a second gate switch coupled to a gate input of the second charge
switch, and a second gate-drive capacitor coupled to the gate input
of the first charge switch.
Inventors: |
Din; Jose Bernardo; (Metro
Manila, PH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Analog Devices Global Unlimited Company |
Hamilton |
|
BM |
|
|
Family ID: |
68314830 |
Appl. No.: |
15/980342 |
Filed: |
May 15, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G05F 1/46 20130101; H02M
3/07 20130101 |
International
Class: |
H02M 3/07 20060101
H02M003/07 |
Claims
1. A charge pump circuit comprising: a first charge transfer
circuit path coupled including a first boost capacitor coupled to a
first clock input, a first charge switch coupled to a circuit
input, and a first discharge switch coupled to a circuit output,
wherein a source-or-drain connection of the first charge switch is
coupled to a source-or-drain connection of the first discharge
switch; a second charge transfer circuit path including a second
boost capacitor coupled to a second clock input, a second charge
switch coupled to the circuit input, and a second discharge switch
coupled to the circuit output, wherein a source-or-drain connection
of the second charge switch is coupled to a source-or-drain
connection of the second discharge switch; a first charge control
circuit including a first gate switch coupled to a gate input of
the first charge switch, and a first gate-drive capacitor coupled
to a third clock input and the gate input of the second charge
switch; and a second charge control circuit including a second gate
switch coupled to a gate input of the second charge switch, and a
second gate-drive capacitor coupled to a fourth clock input and the
gate input of the first charge switch.
2. The charge pump circuit of claim 1, wherein the first boost
capacitor is coupled to a gate input of the second discharge
switch, and the second boost capacitor is coupled to a gate input
of the first discharge switch.
3. The charge pump circuit of claim 1, wherein a gate input of the
first gate switch is coupled to the first gate-drive capacitor, and
a gate input of the second gate switch is coupled to the second
gate-drive capacitor.
4. The charge pump circuit of claim 1, wherein a gate input of the
first gate switch is coupled to the first boost capacitor, and a
gate input of the second gate switch is coupled to the second boost
capacitor.
5. The charge pump circuit of claim 1, including a clamping circuit
coupled to limit voltage at the gate input of the first charge
switch and the gate input of the second charge switch.
6. The charge pump circuit of claim 1, wherein the first clock
input and the third clock input receive a first clock signal, and
the second clock input and the fourth clock input receive a second
clock signal having opposite signal polarity of the first clock
signal.
7. The charge pump circuit of claim 1, wherein the first, second,
third, and fourth clock inputs each receive a separate clock signal
to advance the charge pump circuit through five operating
states.
8. The charge pump circuit of claim 1, wherein the first, second,
third, and fourth clock inputs each receive respective first,
second, third and fourth clock signals, wherein the first and
second clock signals have opposite polarity and are
non-overlapping, and the third and fourth clock signals have
opposite polarity and are non-overlapping.
9. The charge pump circuit of claim 1, wherein the first and second
charge transfer paths are included in a first charge pump stage
between a first stage input and a first stage output; the charge
pump circuit further includes a second charge pump stage including
third and fourth charge transfer paths coupled between a second
stage input and second stage output; and the first stage output is
coupled to the second stage input.
10. The charge pump circuit of claim 1, including: a third
gate-drive capacitor coupled to the third clock input and a gate
input of the second discharge switch; and a fourth gate-drive
capacitor coupled to the fourth lock input and a gate input of the
first discharge switch.
11. A charge pump circuit comprising: a first charge transfer
circuit path coupled including a first boost capacitor coupled to a
first clock input, a first charge switch coupled to a circuit
input, and a first discharge switch coupled to a circuit output,
wherein a source-or-drain connection of the first charge switch is
coupled to a source-or-drain connection of the first discharge
switch; a second charge transfer circuit path including a second
boost capacitor coupled to a second clock input, a second charge
switch coupled to the circuit input, and a second discharge switch
coupled to the circuit output, wherein a source-or-drain connection
of the second charge switch is coupled to a source-or-drain
connection of the second discharge switch; a first charge control
circuit including a first gate switch coupled to a gate input of
the first discharge switch, and a first gate-drive capacitor
coupled to a third clock input and the gate input of the second
discharge switch; and a second charge control circuit including a
second gate switch coupled to a gate input of the second discharge
switch, and a second gate-drive capacitor coupled to a fourth clock
input and the gate input of the first discharge switch.
12. The charge pump circuit of claim 11, wherein the first boost
capacitor is coupled to a gate input of the second charge switch,
and the second boost capacitor is coupled to a gate input of the
first charge switch.
13. The charge pump circuit of claim 11, wherein a gate input of
the first gate switch is coupled to the first gate-drive capacitor,
and a gate input of the second gate switch is coupled to the second
gate-drive capacitor.
14. The charge pump circuit of claim 11, wherein a gate input of
the first gate switch is coupled to the first boost capacitor, and
a gate input of the second gate switch is coupled to the second
boost capacitor.
15. The charge pump circuit of claim 11, including a clamping
circuit coupled to limit voltage at the gate input of the first
discharge switch and the gate input of the second discharge
switch.
16. The charge pump circuit of claim 11, wherein the first clock
input and the third clock input receive a first clock signal, and
the second clock input and the fourth clock input receive a second
clock signal having opposite signal polarity of the first clock
signal.
17. The charge pump circuit of claim 11, wherein the first, second,
third, and fourth clock inputs each receive a separate clock signal
to advance the charge pump circuit through five operating
states.
18. The charge pump circuit of claim 11, wherein the first, second,
third, and fourth clock inputs each receive respective first,
second, third and fourth clock signals, wherein the first and
second clock signals have opposite polarity and are
non-overlapping, and the third and fourth clock signals have
opposite polarity and are non-overlapping.
19. The charge pump circuit of claim 11, including: a third
gate-drive capacitor coupled to the third clock input and a gate
input of the second charge switch; and a fourth gate-drive
capacitor coupled to the fourth lock input and a gate input of the
first charge switch.
20. The charge pump circuit of claim 1, including: a pass circuit
including a gate input; and a low drop out (LDO) circuit coupled to
the charge pump circuit output and configured to provide a
regulated voltage to the gate input of the pass circuit.
21. The charge pump circuit of claim 20, wherein the first clock
input and the third clock input receive a first clock signal, and
the second clock input and the fourth clock input receive a second
clock signal having opposite signal polarity of the first clock
signal.
22. The charge pump circuit of claim 20, wherein the first, second,
third, and fourth clock inputs each receive a separate clock signal
to advance the charge pump circuit through five operating
states.
23. A method of operating a charge pump circuit, the method
comprising: charging a first boost capacitor using a circuit input
and a first clock input, wherein the charging of the first boost
capacitor is controlled using a first charge switch and discharging
of the first boost capacitor to a circuit output is controlled
using a first discharge switch coupled to the first charge switch;
charging a second boost capacitor using the circuit input and a
second clock input, wherein the charging of the second boost
circuit is controlled using a second charge switch and discharging
of the second boost capacitor to the circuit output is controlled
using a second discharge switch coupled to the second charge
switch; charging a first drive capacitor using the first clock
input and charging a second drive capacitor using the second clock
input; turning on the first charge switch using the second drive
capacitor to charge the first boost capacitor and turning on the
first discharge switch using the second boost capacitor to
discharge the first boost capacitor; and turning on the second
charge switch using the first drive capacitor to charge the second
boost capacitor and turning on the second discharge switch using
the first boost capacitor to discharge the second boost
capacitor.
24. The method of claim 23, including regulating the output of the
charge pump circuit using a low drop out circuit.
25. The method of claim 24, including providing the regulated
output to a gate input of a pass circuit.
Description
FIELD OF THE DISCLOSURE
[0001] This document relates to integrated circuits and in
particular to charge pump circuits or voltage boost circuits that
provide a boosted voltage from a supply voltage.
BACKGROUND
[0002] In integrated circuit designs there may be a need to boost a
supply voltage (e.g., a battery voltage) to a higher voltage. This
boosting can be accomplished using a charge pump circuit in which
charge is transferred to capacitors and then added to produce an
output voltage that exceeds the voltage supply of the charge pump
circuit. High efficiency circuits are desired for low power
applications. However, charge pump circuits can be inefficient due
to leakage and other parasitic effects during operation of the
circuit.
SUMMARY OF THE DISCLOSURE
[0003] This document relates generally to integrated circuits, and
in particular to circuits that generate a boosted voltage from an
input voltage such as a supply voltage for an integrated circuit.
In some aspects, a charge pump circuit comprises a first charge
transfer circuit path coupled including a first boost capacitor
coupled to a first clock input, a first charge switch coupled to a
circuit input, and a first discharge switch coupled to a circuit
output; a second charge transfer circuit path including a second
boost capacitor coupled to a second clock input, a second charge
switch coupled to the circuit input, and a second discharge switch
coupled to the circuit output; a first charge control circuit
including a first gate switch coupled to a gate input of the first
charge switch, and a first gate-drive capacitor coupled to the gate
input of the second charge switch; and a second charge control
circuit including a second gate switch coupled to a gate input of
the second charge switch, and a second gate-drive capacitor coupled
to the gate input of the first charge switch.
[0004] In some aspects, a charge pump circuit comprises a first
charge transfer circuit path coupled including a first boost
capacitor coupled to a first clock input, a first charge switch
coupled to a circuit input, and a first discharge switch coupled to
a circuit output; a second charge transfer circuit path including a
second boost capacitor coupled to a second clock input, a second
charge switch coupled to the circuit input, and a second discharge
switch coupled to the circuit output; a first charge control
circuit including a first gate switch coupled to a gate input of
the first discharge switch, and a first gate-drive capacitor
coupled to a third clock input and the gate input of the second
discharge switch; and a second charge control circuit including a
second gate switch coupled to a gate input of the second discharge
switch, and a second gate-drive capacitor coupled to a fourth clock
input and the gate input of the first discharge switch.
[0005] In some aspects, an electronic circuit comprises a charge
pump circuit, a pass circuit including a gate input; and a low drop
LDO circuit coupled to the charge pump circuit output and
configured to provide a regulated voltage to the gate input of the
pass circuit. The charge pump circuit includes a first charge
transfer circuit path coupled including a first boost capacitor
coupled to a first clock input, a first charge switch coupled to a
circuit input, and a first discharge switch coupled to a circuit
output; a second charge transfer circuit path including a second
boost capacitor coupled to a second clock input and a gate input of
the first discharge switch, a second charge switch coupled to the
circuit input, and a second discharge switch coupled to the circuit
output and including a gate input coupled to the first boost
capacitor, a first charge control circuit including a first gate
switch coupled to a gate input of the first charge switch, and a
first gate-drive capacitor coupled to a third clock input and the
gate input of the second charge switch; and a second charge control
circuit including a second gate switch coupled to a gate input of
the second charge switch, and a second gate-drive capacitor coupled
to a fourth clock input and the gate input of the first charge
switch.
[0006] This section is intended to provide an overview of subject
matter of the present patent application. It is not intended to
provide an exclusive or exhaustive explanation of the invention.
The detailed description is included to provide further information
about the present patent application.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] In the drawings, which are not necessarily drawn to scale,
like numerals may describe similar components in different views.
Like numerals having different letter suffixes may represent
different instances of similar components. The drawings illustrate
generally, by way of example, but not by way of limitation, various
embodiments discussed in the present document.
[0008] FIG. 1 is a circuit diagram of charge pump circuit in an
aspect.
[0009] FIG. 2 is a timing diagram of clock signals used to drive a
charge pump circuit in an aspect.
[0010] FIG. 3 is a circuit diagram of a charge pump circuit in
another aspect.
[0011] FIG. 4 is a circuit diagram of a charge pump circuit in
another aspect.
[0012] FIG. 5 is a timing diagram of clock signals used to drive a
charge pump circuit in another aspect.
[0013] FIG. 6 is a flow diagram of the operating state transitions
of a charge pump circuit in an aspect.
[0014] FIG. 7 is a circuit diagram of a charge pump circuit in
another aspect.
[0015] FIG. 8 is a circuit diagram of a charge pump circuit in
another aspect.
[0016] FIG. 9 is a circuit diagram of a charge pump circuit in
another aspect.
[0017] FIG. 10 is a circuit diagram of a charge pump circuit in
another aspect.
[0018] FIG. 11 is a block diagram of a charge pump circuit in
another aspect.
[0019] FIG. 12 is a block diagram of a charge pump circuit in
another aspect.
[0020] FIG. 13 is a diagram of an electronic circuit in an
aspect.
DETAILED DESCRIPTION
[0021] This document relates to charge pump circuits that generate
a boosted output voltage higher than the input supply voltage. For
low power applications, it is desirable to operate charge pump
circuits at a low input voltage (VIN). However, conventional charge
pump circuits can be inefficient at low voltages.
[0022] FIG. 1 is a circuit diagram of a charge pump circuit 100 in
an aspect. The circuit includes two asynchronous charge transfer
circuit paths. In the first part of a charge-discharge cycle, a
boost capacitor 102 of one of the charge transfer paths is charged
using the input voltage VIN, and in the second part of the
charge-discharge cycle, the voltage on the boost capacitor 102 is
added to the voltage of a clock signal (CLK1) and provided to the
output VOUT. This charge-discharge cycling of the boost capacitor
is alternated with charge-discharge cycling of the boost capacitor
104 of the other charge transfer path to generate the output
voltage (VOUT). If the voltage of the CLK signals is nearly the
same as VIN, the generated VOUT is approximately twice VIN.
[0023] In FIG. 1, the first charge transfer circuit path includes
boost capacitor 102, charge switch 106, and discharge switch 108.
The switches can be field effect transistor (FETs). As shown in
FIG. 1, the charge switch 106 can be an n-channel FET (NFET or NMOS
transistor) and discharge switch 108 can be a p-channel FET (PFET
or PMOS transistor). The boost capacitor 102 is connected to a
clock signal (CLK1). On a first phase of the clock signal, the
charge switch 106 is activated to provide the input voltage to the
boost capacitor when the clock signal is LOW. On a second phase of
the clock signal, the discharge switch 108 is activated, and the
voltage of the boost capacitor VIN is added to the clock signal and
provided to the circuit output (VOUT). Capacitor C.sub.LOAD at the
output represents the output capacitive load. Voltage V.sub.BIAS
can be circuit ground or another voltage level.
[0024] The second charge transfer circuit path includes boost
capacitor 104, charge switch 110, and discharge switch 112. As in
the first charge transfer path, the charge switch 110 can be an
NFET and the discharge switch 112 can be a PFET. The boost
capacitor 104 is connected to a second clock signal (CLK2). The
charge transfer of the second charge transfer path works similar to
the change transfer of the first charge transfer path except that
the charging and discharging of the boost capacitor 104 is out of
phase with the charging and discharging of boost capacitor 102.
[0025] FIG. 2 is a timing diagram of clock signals used to drive
the charge pump circuit of FIG. 1 in an aspect. The clock signals
each have a 50% duty cycle and have opposite polarity or opposite
phase. As an example, the clock signals may each have a frequency
of forty megahertz (40 MHz). Because the charge transfer paths
operate with opposite phase, the voltage provided to the circuit
output is approximately VIN plus the voltage of the clock signals
minus voltage drops of passing through the switches and losses of
the capacitors.
[0026] Returning to FIG. 1, the charge pump circuit 100 also
includes charge control circuits to control the gate input of the
charge switches. The first charge control circuit includes
gate-drive capacitor 116 that is coupled to the gate input of the
second charge switch 110 and clock signal CLK1. The second charge
control circuit includes gate-drive capacitor 118 that is coupled
to the gate input of the first charge switch 106 and clock signal
CLK2. The capacitance of the gate-drive capacitors is smaller than
the capacitance of the boost capacitors. The gate-drive capacitors
are charged when the clock signals are LOW, and the voltage on the
gate-drive capacitors is used to drive the gates of the charge
switches. The gate inputs of the discharge switches are driven by
cross-coupling the boost capacitors to the gate inputs. The first
boost capacitor 102 is coupled to the gate input of the second
discharge switch 112, and the second boost capacitor 104 is coupled
to the gate input of the first discharge switch 108.
[0027] The first charge control circuit also includes gate switch
114 coupled to the gate input of the first charge switch 106, and
the second charge control circuit includes gate switch 120 coupled
to the gate input of the second charge switch 110. In the example
of FIG. 1, gate switches 114 and 120 are NFETs. Controlling the
gate input of the discharge switches with the boost capacitors and
controlling the gate inputs of the charge switches with separate
gate-drive capacitors can reduce the effect of parasitic charge
sharing at the gate inputs of the charge and discharge
switches.
[0028] The charge pump circuit 100 also includes a clamping circuit
coupled to the gates of the charge switches. In FIG. 1, the
clamping circuit includes PFETs 122 and 124 with the source
electrically shorted to the gate. In certain aspects, diodes can be
substituted for PFETs 122 and 124. The gate switches and the
clamping circuit serve to limit the voltage at the gates of the
charge switches to prevent the voltage across the gate terminals
from exceeding the breakdown voltage.
[0029] FIG. 3 is a circuit diagram of a charge pump circuit 300 in
another aspect. Similar to the circuit of FIG. 1, the charge pump
circuit includes two charge transfer paths and two control
circuits. The circuit of FIG. 3 differs from the circuit of FIG. 1
in that the gate inputs to the gate switches are controlled by the
boost capacitors. The gate input of gate switch 314 is coupled to
boost capacitor 302, and the gate input of gate switch 320 is
coupled to boost capacitor 304.
[0030] FIG. 4 is a circuit diagram of a charge pump circuit 400 in
another aspect. The circuit is the same as the charge pump circuit
200 of FIG. 2 except that separate clock inputs receive separate
clock signals for the boost capacitors and the gate drive
capacitors. Clock signal CLK1 and clock signal CLK 2 are connected
to boost capacitors 402 and 404 respectively as in the circuit of
FIG. 1. A third clock signal CLK3 separate from CLK1 is provided to
gate-drive capacitor 416, and a fourth clock signal CLK4 separate
from clock signal CLK2 is provided to gate-drive capacitor 418.
Different switches are clock on different phases of the four clock
signals. This prevents reverse current flowing from the circuit
output toward the circuit input. The 4-phase clock signaling
ensures that the NFET charge switches are off before the PFET
discharge switches turn on. It also ensures that the clock signal
at a boost capacitor is HIGH and the boost capacitor is ready to
transfer charge before the discharge switches turn on. The 4-phase
clock signaling operation may be more efficient for higher VIN
voltages.
[0031] FIG. 5 is a timing diagram of clock signals used to drive
the charge pump circuit of FIG. 4 in an aspect. The clock signals
can be generated using a clock circuit included on the same
integrated circuit as the charge pump circuit. In a non-limiting
example, the duty cycle (i.e., the time that the clock signal is
HIGH compared to the time that the clock signal is LOW) for clock
signals CLK3 and CLK2 can be 44%, and the duty cycle for clock
signals CLK1 and CLK4 can be 52%. Clock signals CLK1 and CLK4 may
be non-overlapping clock signals, and clock signals CLK2 and CLK3
may be non-overlapping clock signals.
[0032] The 4-phase clock signaling advances the charge pump circuit
400 through five operating states in an aspect. In the timing
diagram, time t.sub.1 corresponds to State 1 in which the clock
signals (CLK1, CLK3) to capacitors 402 and 416 are HIGH, and the
clock signals (CLK2, CLK4) to capacitors 404 and 418 are LOW.
[0033] Discharge switch 408 is ON to discharge boost capacitor 402
to the output. Gate-drive capacitor 416 turns charge switch 410 ON
to charge boost capacitor 404 and turns gate switch 414 ON to
charge gate-drive capacitor 418. Charge switch 406, discharge
switch 412, and gate switch 420 are OFF.
[0034] Time t.sub.2 corresponds to State 2 after CLK3 transitions
to LOW to turn OFF charge switch 410 and gate switch 414. Discharge
switch 408 remains ON, and charge switch 406, discharge switch 412,
and gate switch 420 remain OFF.
[0035] Time t3 corresponds to State 3 after CLK2 transitions to
HIGH. CLK1 is still HIGH and CLK3 and CLK4 are LOW. All of the
switches are OFF. Some discharge current flows from boost capacitor
404 to the output through a parasitic diode of discharge switch
412.
[0036] Time t4 corresponds to State 4 after CLK1 transitions to
LOW. CLK2 is still HIGH and CLK3 and CLK4 are LOW. Discharge switch
412 is ON to discharge boost capacitor 404 to the output. Some
charging current flows to boost capacitor 402 from the input
through the parasitic diode of charge switch 406.
[0037] Time t5 corresponds to State 5 after CLK4 transitions to
HIGH. CLK2 is still HIGH and CLK3 and CLK 1 are LOW. Charge switch
406 is ON to charge boost capacitor 406, and gate switch 420 is ON
to charge gate-drive capacitor 416. Discharge switch 412 is still
ON to discharge boost capacitor 404 to the output.
[0038] The charge pump then progresses through from State 5 through
intermediate States 4-2 back to State 1. At time t.sub.6, the
charge pump circuit is still in State 5. The charge pump
transitions to State 4 at time t.sub.7, to State 3 at time t.sub.8,
to State 2 at time t.sub.9, and back to State 1 at time t.sub.10.
FIG. 6 is a flow diagram of the operating state transitions. The
clock signals repeat to transition the charge pump circuit from
State 1 through intermediates states 2-4 back to state 5.
[0039] It can be seen that the charge pump circuit of FIG. 4 cycles
between discharging boost capacitor 402 and charging boost
capacitor 404 in State 1, and charging boost capacitor 402 and
discharging boost capacitor 404 in State 5 to generate boosted
voltage VOUT. No reverse current flows in any of the operating
states.
[0040] FIG. 7 is a circuit diagram of a charge pump circuit 700 in
another aspect. In this version, the charge pump circuit 700
includes two charge transfer circuit paths as before. However, the
boost capacitors are used to control the gate inputs of the charge
switches and the gate-drive capacitors are used to control the gate
inputs of the discharge switches. Boost capacitor 702 is coupled to
the gate input of charge switch 710, and boost capacitor 704 is
coupled to the gate input of charge switch 706. Gate drive
capacitor 716 is coupled to the gate input of discharge switch 712,
and gate-drive capacitor 718 is coupled to the gate input of
discharge switch 708.
[0041] Another difference is that the gate switches are coupled to
the discharge switches instead of the charge switches. Gate switch
714 is coupled to the gate input of discharge switch 708, and gate
switch 720 is coupled to the gate input of discharge switch 712. In
the example of FIG. 7, gate switches 714 and 720 are PFETs. The
gate inputs of gate switches 714 and 720 are shown connected to
gate-drive capacitors 716 and 718, respectively.
[0042] Still another difference is that the clamping circuit is
coupled to limit the voltage at the gate inputs of the discharge
switches instead of the charge switches. In FIG. 7, the clamping
circuit includes NFETs 722 and 724 that have the source
electrically shorted to the gate. In certain aspects, diodes can be
substituted for the NFETs. The gate switches and the clamping
circuit serve to limit the voltage at the gates of the discharge
switches to prevent the voltage across the gate terminals from
exceeding the breakdown voltage. The charge pump circuit of FIG. 7
is shown driven by two clock signals. Boost capacitor 702 and
gate-drive capacitor 716 are driven by clock signal CLK1, and boost
capacitor 704 and gate-drive capacitor 718 are driven by clock
signal CLK2. In another aspect, four separate clock signals can be
used to drive the four capacitors as in the example of FIG. 4. The
four clock signals may provide 4-phase clock signaling as in FIG. 5
to advance the charge pump circuit 700 through five operating
states.
[0043] FIG. 8 is a circuit diagram of a charge pump circuit 800 in
another aspect. Similar to the circuit of FIG. 7, the charge pump
circuit 800 includes two charge transfer paths and two control
circuits. The circuit of FIG. 8 differs from the circuit of FIG. 7
in that the gate input of gate switch 814 is coupled to boost
capacitor 802, and the gate input of gate switch 820 is coupled to
boost capacitor 804.
[0044] FIG. 9 is a circuit diagram of a charge pump circuit 900 in
another aspect. The charge pump circuit includes two charge
transfer circuit paths as in the previous examples. However, the
boost capacitors are not used to control either the discharge
switches (as in the circuit of FIG. 1) or the charge switches (as
in the circuit of FIG. 7). Instead, two additional gate-drive
capacitors are used to control both the charge switches and the
discharge switches. Similar to FIG. 1, gate-drive capacitor 916 is
coupled to the gate input of charge switch 910, and gate-drive
capacitor 918 is coupled to the gate input of charge switch 906.
Similar to FIG. 7, gate-drive capacitor 926 is coupled to the gate
input of discharge switch 912, and gate-drive capacitor 928 is
coupled to the gate input of discharge switch 908. Two separate VIN
connections and two separate VOUT connections are shown for
simplicity, but in actuality the two nodes labeled VIN are a common
input connection, and the two nodes labeled VOUT are a common
output connection.
[0045] The circuit of FIG. 9 includes four gate switches 914, 920,
930, 932. The gate input of the gate switches are each coupled to a
gate-drive capacitor. The gate input of gate switch 914 is coupled
to gate-drive capacitor 916, the gate input of gate switch 920 is
coupled to gate-drive capacitor 918, the gate input of gate switch
930 is coupled to gate-drive capacitor 926, and the gate input of
gate switch 932 is coupled to gate-drive capacitor 928. In another
aspect, the gate inputs of the gate switches can be coupled to
boost capacitors as in the example of FIG. 3. The gate inputs of
gate switches 914 and 930 can be coupled to boost capacitor 902,
and the gate inputs of gate switches 920 and 932 can be coupled to
boost capacitor 904.
[0046] The charge pump circuit of FIG. 9 also includes two clamping
circuits to limit the gate of the charge switches and discharge
switches. One clamping circuit includes PFETs 922 and 924, and the
other clamping circuit includes NFETs 934 and 936.
[0047] The charge pump circuit of FIG. 9 is shown driven by two
clock signals. Boost capacitor 902 and gate-drive capacitors 916
and 926 are driven by clock signal CLK 1, and boost capacitor 904
and gate-drive capacitors 918 and 928 are driven by clock signal
CLK2. In another aspect, four separate clock signals can be used to
drive the six capacitors (similar to the example of FIG. 4) by
separating each of CLK1 and CLK 2 into two clock signals. CLK1 can
be separated into a first clock signal to drive boost capacitor 902
and a second clock signal to drive gate-drive capacitors 916 and
926. CLK2 can be separated into a first clock signal to drive boost
capacitor 904 and a second clock signal to drive gate-drive
capacitors 918 and 928. The four clock signals may provide 4-phase
clock signaling as in FIG. 5 to advance the charge pump circuit 900
through five operating states.
[0048] FIG. 10 is a circuit diagram of a charge pump circuit 1000
in another aspect. The circuit is similar to the circuit of FIG. 9
except that some gate switches are activated using the boost
capacitors instead of the gate drive capacitors. The gate input of
gate switches 1014 and 1030 are coupled to boost capacitor 1002,
and the gate input of gate switches 1020 and 1032 are coupled to
boost capacitor 1004.
[0049] For the charge pump circuits described previously herein,
the generated output voltage VOUT is approximately twice VIN. To
generate a higher output voltage, a charge pump circuit can be
cascaded in series with more charge pump circuits with the output
of one charge pump circuit provided as the input to the next stage.
For example, two of the charge pump circuits of FIG. 1 may be
cascaded as a first charge pump stage and a second charge pump
stage. The first charge pump stage includes first and second charge
transfer paths to produce a boosted voltage at the output which is
coupled to the input of the second stage input. The second charge
pump stage includes third and fourth charge transfer paths to boost
the voltage at its input. Each additional stage boosts its input
voltage by VIN. The output of the first charge pump stage is
approximately two times VIN, and the output of the second charge
pump stage is approximately three time VIN. This cascading can be
extended to more charge pump stages. The number of times that VIN
is boosted is approximately the number of cascaded stages plus one.
For example, two charge pump stages generate approximately three
times VIN, and three charge pump stages produce approximately four
times VIN.
[0050] FIG. 11 is a circuit diagram of a charge pump circuit 1100
in another aspect. The circuit includes N cascaded charge pump
cells, wherein N is a positive integer. Each cell 1138 provides its
boosted voltage to the next cell. The charge pump cells can be any
of the two clock signal examples in which the clock signals CLK1
and CLK 2 are connected to the boost capacitors and the gate drive
capacitors. The charge pump circuit generates approximately N+1
times the input voltage. For example, a charge pump circuit with
nine charge pump cells (i.e., N=9) would generate ten times the
input voltage.
[0051] FIG. 12 is a circuit diagram of a charge pump circuit 1200
in another aspect. The circuit includes N cascaded charge pump
cells, and the charge pump circuit generates approximately N+1
times the input voltage. The charge pump cells 1238 use the 4-phase
clocking scheme described herein with separate clock signals
driving the boost capacitors and the gate-drive capacitors.
[0052] The charge pump cells of FIGS. 11 and 12 do not all have to
be the type of cell and can include any combination of the charge
pump circuits described herein. However, using the same type
simplifies the layout of the charge pump circuit. The charge pump
cells can be operated by distributing the same clock signals to the
charge pump cells. The charge pump cells may include a clock signal
buffer to receive the clock signals from a centralized clock
circuit and reduce the load on the distributed clock signals.
[0053] The boosted voltage generated by the charge pump circuits
described herein can be used in an IC to process signals that are
greater than the supply voltage. For example, a circuit designer
may want to pass a signal through a switch that has a greater
amplitude than the supply voltage provided to the control input of
the switch. Normally, passing such a signal through a switch
circuit normally would result in the switch being turned off. For
example, if the switch circuit includes FET, an input signal having
too great an amplitude may result in the gate to source voltage
(V.sub.GS) reaching the breakdown point. This may result in the
output signal being clipped at, or slightly below, the supply
voltage. Providing the boosted voltage to the control input of the
switch resolves the problem.
[0054] FIG. 13 is a circuit diagram of an electronic circuit 1340
that includes a charge pump circuit 1300, a pass circuit 1342, and
a low drop out (LDO) circuit 1344. The charge pump circuit 1300 can
be any of the charge pump circuits described herein, including a
charge pump circuit formed using multiple cascaded charge pump
stages. The pass circuit 1342 can be an NFET. The LDO circuit 1344
provides a regulated voltage to the gate input of the pass circuit
1344.
[0055] The charge pump circuits described herein provide several
advantages that make them useful for integrated circuit (IC)
applications. The minimum input voltage VIN can be close to the
threshold level of the switches of the circuits. The maximum VIN is
determined by the IC process. For example, a charge pump circuit
for an IC with a six volt (6V) process could accommodate a 6.5V
maximum VIN. The boost capacitors of the charge pump circuits can
be fully integrated. Cascaded cells can provide high gain. Because
the charge pump circuits cycle between two charge transfer paths,
the charge pump circuits exhibit low ripple on the output voltage.
The charge pump circuits are efficient because of reduce parasitic
circuit effects at the gate inputs of the switches. Using 4-phase
clocking for the charge pump circuits further increases efficiency
by preventing reverse current in the circuits.
ADDITIONAL DESCRIPTION AND ASPECTS
[0056] Aspect 1 can include subject matter (such as a charge pump
circuit) comprising a first charge transfer circuit path coupled
including a first boost capacitor coupled to a first clock input, a
first charge switch coupled to a circuit input, and a first
discharge switch coupled to a circuit output; a second charge
transfer circuit path including a second boost capacitor coupled to
a second clock input, a second charge switch coupled to the circuit
input, and a second discharge switch coupled to the circuit output;
a first charge control circuit including a first gate switch
coupled to a gate input of the first charge switch, and a first
gate-drive capacitor coupled to a third clock input and the gate
input of the second charge switch; and a second charge control
circuit including a second gate switch coupled to a gate input of
the second charge switch, and a second gate-drive capacitor coupled
to a fourth clock input and the gate input of the first charge
switch.
[0057] In Aspect 2, the subject matter of Aspect 1 optionally
includes the first boost capacitor coupled to a gate input of the
second discharge switch, and the second boost capacitor coupled to
a gate input of the first discharge switch.
[0058] In Aspect 3, the subject matter of one or both of Aspects 1
and 2 optionally includes a gate input of the first gate switch
coupled to the first gate-drive capacitor, and a gate input of the
second gate switch coupled to the second gate-drive capacitor.
[0059] In Aspect 4, the subject matter of one or both of Aspects 1
and 2 optionally includes a gate input of the first gate switch
coupled to the first boost capacitor, and a gate input of the
second gate switch coupled to the second boost capacitor.
[0060] In Aspect 5, the subject matter of one or any combination of
Aspects 1-4 optionally includes a clamping circuit coupled to limit
voltage at the gate input of the first charge switch and the gate
input of the second charge switch.
[0061] In Aspect 6, the subject matter of one or any combination of
Aspects 1-5 optionally includes the first clock input and the third
clock input receiving a first clock signal, and the second clock
input and the fourth clock input receiving a second clock signal
having opposite signal polarity of the first clock signal.
[0062] In Aspect 7, the subject matter of one or any combination of
Aspects 1-5 optionally includes the first, second, third, and
fourth clock inputs each receiving a separate clock signal to
advance the charge pump circuit through five operating states.
[0063] In Aspect 8, the subject matter of one or any combination of
Aspects 1-5 and 7 optionally includes the first, second, third, and
fourth clock inputs each receive respective first, second, third
and fourth clock signals, wherein the first and second clock
signals have opposite polarity and are non-overlapping, and the
third and fourth clock signals have opposite polarity and are
non-overlapping.
[0064] In Aspect 9, the subject matter of one or any combination of
Aspects 1-8 optionally includes the first and second charge
transfer paths are included in a first charge pump stage between a
first stage input and a first stage output; the charge pump circuit
further includes a second charge pump stage including third and
fourth charge transfer paths coupled between a second stage input
and second stage output; and the first stage output is coupled to
the second stage input.
[0065] In Aspect 10, the subject matter of one or any combination
of Aspects 1-9 optionally includes a third gate-drive capacitor
coupled to the third clock input and a gate input of the second
discharge switch; and a fourth gate-drive capacitor coupled to the
fourth lock input and a gate input of the first discharge
switch.
[0066] Aspect 11 includes subject matter (such as a charge pump
circuit), or can optionally be combined with one or any combination
of Aspects 1-10 to include such subject matter, comprising: a first
charge transfer circuit path coupled including a first boost
capacitor coupled to a first clock input, a first charge switch
coupled to a circuit input, and a first discharge switch coupled to
a circuit output; a second charge transfer circuit path including a
second boost capacitor coupled to a second clock input, a second
charge switch coupled to the circuit input, and a second discharge
switch coupled to the circuit output; a first charge control
circuit including a first gate switch coupled to a gate input of
the first discharge switch, and a first gate-drive capacitor
coupled to a third clock input and the gate input of the second
discharge switch; and a second charge control circuit including a
second gate switch coupled to a gate input of the second discharge
switch, and a second gate-drive capacitor coupled to a fourth clock
input and the gate input of the first discharge switch.
[0067] In Aspect 12, the subject matter of Aspect 11 optionally
includes the first boost capacitor coupled to a gate input of the
second charge switch, and the second boost capacitor coupled to a
gate input of the first charge switch.
[0068] In Aspect 13, the subject matter of one or both of Aspects
11 and 12 optionally includes a gate input of the first gate switch
is coupled to the first gate-drive capacitor, and a gate input of
the second gate switch is coupled to the second gate-drive
capacitor.
[0069] In Aspect 14, the subject matter of one or any combination
of Aspects 11-13 optionally includes a gate input of the first gate
switch is coupled to the first boost capacitor, and a gate input of
the second gate switch is coupled to the second boost
capacitor.
[0070] In Aspect 15, the subject matter of one or any combination
of Aspects 11-14 optionally includes a clamping circuit coupled to
limit voltage at the gate input of the first discharge switch and
the gate input of the second discharge switch.
[0071] In Aspect 16, the subject matter of one or any combination
of Aspects 11-15 optionally includes the first clock input and the
third clock input receiving a first clock signal, and the second
clock input and the fourth clock input receiving a second clock
signal having opposite signal polarity of the first clock
signal.
[0072] In Aspect 17, the subject matter of one or any combination
of Examples 11-15 optionally includes the first, second, third, and
fourth clock inputs each receive a separate clock signal to advance
the charge pump circuit through five operating states.
[0073] In Aspect 18, the subject matter of one or any combination
of Aspects 11-15 and 17 optionally includes the first, second,
third, and fourth clock inputs each receive respective first,
second, third and fourth clock signals, wherein the first and
second clock signals have opposite polarity and are
non-overlapping, and the third and fourth clock signals have
opposite polarity and are non-overlapping.
[0074] In Aspect 19, the subject matter of one or any combination
of Aspects 11-18 optionally includes a third gate-drive capacitor
coupled to the third clock input and a gate input of the second
charge switch; and a fourth gate-drive capacitor coupled to the
fourth lock input and a gate input of the first charge switch
Aspect 20 can include subject matter (such as an electronic
circuit), or can optionally be combined with one or any combination
of Examples 1-19 to include such subject matter, comprising a
charge pump circuit, a pass circuit, and a low drop out (LDO)
circuit. The charge pump circuit includes: a first charge transfer
circuit path coupled including a first boost capacitor coupled to a
first clock input, a first charge switch coupled to a circuit
input, and a first discharge switch coupled to a circuit output; a
second charge transfer circuit path including a second boost
capacitor coupled to a second clock input and a gate input of the
first discharge switch, a second charge switch coupled to the
circuit input, and a second discharge switch coupled to the circuit
output and including a gate input coupled to the first boost
capacitor; a first charge control circuit including a first gate
switch coupled to a gate input of the first charge switch, and a
first gate-drive capacitor coupled to a third clock input and the
gate input of the second charge switch; and a second charge control
circuit including a second gate switch coupled to a gate input of
the second charge switch, and a second gate-drive capacitor coupled
to a fourth clock input and the gate input of the first charge
switch. The pass circuit includes a gate input, and the LDO circuit
is coupled to the charge pump circuit output and configured to
provide a regulated voltage to the gate input of the pass
circuit.
[0075] In Aspect 21, the subject matter of Aspect 20 optionally
includes the first clock input and the third clock input receiving
a first clock signal, and the second clock input and the fourth
clock input receiving a second clock signal having opposite signal
polarity of the first clock signal.
[0076] In Aspect 22, the subject matter of Aspect 20 optionally
includes the first, second, third, and fourth clock inputs each
receive a separate clock signal to advance the charge pump circuit
through five operating states.
[0077] These non-limiting Aspects can be combined in any
permutation or combination. The above detailed description includes
references to the accompanying drawings, which form a part of the
detailed description. The drawings show, by way of illustration,
specific embodiments in which the invention can be practiced. These
embodiments are also referred to herein as "examples." All
publications, patents, and patent documents referred to in this
document are incorporated by reference herein in their entirety, as
though individually incorporated by reference. In the event of
inconsistent usages between this document and those documents so
incorporated by reference, the usage in the incorporated
reference(s) should be considered supplementary to that of this
document; for irreconcilable inconsistencies, the usage in this
document controls.
[0078] In this document, the terms "a" or "an" are used, as is
common in patent documents, to include one or more than one,
independent of any other instances or usages of"at least one" or
"one or more." In this document, the term "or" is used to refer to
a nonexclusive or, such that "A or B" includes "A but not B," "B
but not A," and "A and B," unless otherwise indicated. In the
appended claims, the terms "including" and "in which" are used as
the plain-English equivalents of the respective terms "comprising"
and "wherein." Also, in the following claims, the terms "including"
and "comprising" are open-ended, that is, a system, device,
article, or process that includes elements in addition to those
listed after such a term in a claim are still deemed to fall within
the scope of that claim. Moreover, in the following claims, the
terms "first," "second," and "third," etc. are used merely as
labels, and are not intended to impose numerical requirements on
their objects. Method examples described herein can be machine or
computer-implemented at least in part.
[0079] The above description is intended to be illustrative, and
not restrictive. For example, the above-described examples (or one
or more aspects thereof) may be used in combination with each
other. Other embodiments can be used, such as by one of ordinary
skill in the art upon reviewing the above description. The Abstract
is provided to comply with 37 C.F.R. .sctn. 1.72(b), to allow the
reader to quickly ascertain the nature of the technical disclosure.
It is submitted with the understanding that it will not be used to
interpret or limit the scope or meaning of the claims. Also, in the
above Detailed Description, various features may be grouped
together to streamline the disclosure. This should not be
interpreted as intending that an unclaimed disclosed feature is
essential to any claim. Rather, inventive subject matter may lie in
less than all features of a particular disclosed embodiment. Thus,
the following claims are hereby incorporated into the Detailed
Description, with each claim standing on its own as a separate
embodiment. The scope of the invention should be determined with
reference to the appended claims, along with the full scope of
equivalents to which such claims are entitled.
* * * * *