U.S. patent application number 15/654694 was filed with the patent office on 2017-11-02 for control circuit and control system.
The applicant listed for this patent is MEDIATEK INC.. Invention is credited to Chen-Feng Chiang, Che-Yuan Jao.
Application Number | 20170315577 15/654694 |
Document ID | / |
Family ID | 53180512 |
Filed Date | 2017-11-02 |
United States Patent
Application |
20170315577 |
Kind Code |
A1 |
Jao; Che-Yuan ; et
al. |
November 2, 2017 |
CONTROL CIRCUIT AND CONTROL SYSTEM
Abstract
A control circuit comprising a driving circuit, which comprises
a voltage adjusting circuit for generating a control voltage, and
comprises a first transistor and a second transistor. The first
transistor comprises: a first terminal; a second terminal; and a
control terminal, for receiving a bias voltage generated from at
least operating voltage of the control circuit. The second
transistor comprises: a first terminal, coupled to a second
terminal of the first transistor; a second terminal, for receiving
a first predetermined voltage; and a control terminal, for
receiving the control voltage. The control circuit further
comprises: a candidate voltage selecting circuit, for outputting
one of a plurality of candidate voltages; and a voltage selecting
circuit, for outputting one of the candidate voltage output from
the candidate voltage selecting circuit and a ground voltage as the
bias voltage.
Inventors: |
Jao; Che-Yuan; (Hsinchu
City, TW) ; Chiang; Chen-Feng; (Chiayi County,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MEDIATEK INC. |
Hsin-Chu |
|
TW |
|
|
Family ID: |
53180512 |
Appl. No.: |
15/654694 |
Filed: |
July 19, 2017 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
14599553 |
Jan 19, 2015 |
9746866 |
|
|
15654694 |
|
|
|
|
62001640 |
May 22, 2014 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F 1/26 20130101; Y02D
10/172 20180101; G05F 3/02 20130101; G06F 1/3296 20130101; Y02D
10/00 20180101 |
International
Class: |
G05F 3/02 20060101
G05F003/02; G06F 1/26 20060101 G06F001/26; G06F 1/32 20060101
G06F001/32 |
Claims
1. A control circuit, comprising: a driving circuit, comprising a
voltage adjusting circuit for generating a control voltage,
comprising a first transistor and a second transistor; wherein the
first transistor comprises: a first terminal; a second terminal;
and a control terminal, for receiving a bias voltage generated from
at least operating voltage of the control circuit; wherein the
second transistor comprises: a first terminal, coupled to a second
terminal of the first transistor; a second terminal, for receiving
a first predetermined voltage; and a control terminal, for
receiving the control voltage; wherein the control circuit further
comprises: a candidate voltage selecting circuit, for outputting
one of a plurality of candidate voltages; and a voltage selecting
circuit, for outputting one of the candidate voltage output from
the candidate voltage selecting circuit and a ground voltage as the
bias voltage; wherein the candidate voltages are related with the
operating voltage of the control circuit and a predetermined
voltage; wherein the control circuit controls a target device
receiving the predetermined voltage.
2. The control circuit of claim 1, wherein the first transistor and
the second transistor are both PMOSFETs, the first terminal are
drain terminals, the second terminal are source terminals, and the
control terminals are gate terminals.
3. The control circuit of claim 1, wherein the first transistor and
the second transistor are both NMOSFETs, the first terminal are
drain terminals, the second terminal are source terminals, and the
control terminals are gate terminals.
4. The control circuit of claim 1, wherein the first terminal of
the first transistor is coupled to an I/O pad.
5. The control circuit of claim 1, wherein the control circuit
further comprises a core device receiving a core voltage, wherein
the bias voltage equals to the core voltage.
6. The control circuit of claim 1, wherein the bias voltage is a
ground voltage.
7. A control system, comprising: a power managing IC (integrated
circuit), for providing a first predetermined voltage; and a
control IC, receiving the first predetermined voltage, comprising:
at least one transistor; a bias voltage receiving terminal, for
receiving a bias voltage generated from at least operating voltage
of the control IC, wherein the bias voltage is applied to bias at
least one transistor in the control IC; wherein the control IC
further comprises a core device receiving a core voltage from the
bias voltage receiving terminal, wherein the bias voltage equals to
the core voltage.
8. The control system of claim 7, wherein the control IC comprises:
a voltage adjusting circuit, for generating a control voltage; a
first transistor, applied as the transistor, comprising: a first
terminal; a second terminal; and a control terminal, for receiving
the bias voltage; and a second transistor, comprising: a first
terminal, coupled to a second terminal of the first transistor; a
second terminal, for receiving the first predetermined voltage; and
a control terminal, for receiving the control voltage.
9. The control system of claim 8, wherein the control IC comprises
an I/O pad, wherein the first terminal of the first transistor is
coupled to the I/O pad.
10. The control system of claim 7, wherein the power managing IC
provides the core voltage to the core device and the control IC via
the bias voltage receiving terminal.
11. The control system of claim 7, wherein the power managing IC
provides the core voltage to the core device via the bias voltage
receiving terminal, and the core device provides the core voltage
as the bias voltage.
12. A control system, comprising: a power managing IC (integrated
circuit), providing a first predetermined voltage; and a control
IC, receiving the first predetermined voltage, comprising: at least
one transistor; a core device, receiving a core voltage; and a bias
voltage generating circuit, for generating a bias voltage applied
to bias the transistor in the control IC according to the core
voltage; wherein the bias voltage equals to the first predetermined
voltage minus the core voltage.
13. The control system of claim 12, wherein the power managing IC
provides the core voltage to the core device and the control IC via
the core voltage receiving terminal, thereby the bias voltage
generating circuit generates the bias voltage according to the core
voltage.
14. The control system of claim 12, wherein the power managing IC
provides the core voltage to the core device via the core voltage
receiving terminal, wherein the core device outputs the core
voltage thereby the bias voltage generating circuit generate the
bias voltage according to the core voltage.
15. A control system, comprising: a voltage generating circuit,
providing a first predetermined voltage; and a control IC,
receiving the first predetermined voltage, comprising: at least one
transistor; wherein the control IC further receives a bias voltage
generated from at least operating voltage of the control IC,
wherein the bias voltage is applied to bias at least one transistor
in the control IC; wherein the voltage generating circuit provides
the bias voltage to the control IC.
16. A control system, comprising: a power managing IC (integrated
circuit), providing a first predetermined voltage; and a control
IC, receiving the first predetermined voltage, comprising: at least
one transistor; wherein the control IC further receives a bias
voltage generated from at least operating voltage of the control
IC, wherein the bias voltage is applied to bias at least one
transistor in the control IC; wherein the bias voltage is a ground
voltage; wherein the control IC comprises: a silicon die, wherein
the transistor is provided in the silicon die; and a package,
comprising the silicon die; wherein a ground voltage source
providing the ground voltage is located in the package and outside
the silicon die.
17. A control system, comprising: a power managing IC (integrated
circuit), for providing a first predetermined voltage; and a
control IC, comprising: at least one transistor; wherein the
control IC receives a bias voltage generated from at least
operating voltage of the control IC, wherein the bias voltage is
applied to bias at least one transistor in the control IC; wherein
the bias voltage is a ground voltage; wherein the control IC
comprises: a silicon die, wherein the transistor is provided in the
silicon die; and a package, comprising the silicon die; wherein a
ground voltage source providing the ground voltage is located in
the silicon die.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of applicant's earlier
application, Ser. No. 14/599,553, filed Jan. 19, 2015, which claims
the benefit of U.S. Provisional Application No. 62/001,640, filed
on May 22, 2014. The contents thereof are included herein by
reference.
BACKGROUND
[0002] The present application relates to a control circuit and a
control system, and particularly relates to a control circuit and a
control system that can provide different bias voltages for a
driving circuit included therein.
[0003] FIG. 1 is a circuit diagram illustrating a conventional
driving circuit 100. As illustrated in FIG. 1, the driving circuit
100 comprises transistors TP1, TP2, TN1, and TN2, which are coupled
in series and coupled to an input/output pad I/O. The transistor
TP2 receives a pull up signal PU. If the pull up signal PU controls
the transistor TP2 to be active, a voltage at the output terminal
OT is pulled up. The transistor TP1 receives a bias voltage Vb1 to
operate in a suitable state.
[0004] Similarly, the transistor TN2 receives a pull down signal
PD. If the pull down signal PD controls the transistor TN2 to be
active, a voltage at the output terminal OT is pulled down. The
transistor TN1 receives a bias voltage Vb2 to operate in a suitable
state.
[0005] However, the bias voltage Vb1 or Vb2 must be provided by
another independent bias voltage source which may occupy more
circuit regions. Also, the bias voltage is always a fixed value
thus cannot meet different requirements.
SUMMARY
[0006] One objective of the present application is providing a
control circuit that can provide different bias voltages to a
driving circuit included therein.
[0007] One objective of the present application is providing a
control system that can provide different bias voltages to a
control IC included therein.
[0008] One embodiment of the present application discloses a
control circuit comprising a driving circuit, which comprises a
voltage adjusting circuit for generating a control voltage, and
comprises a first transistor and a second transistor. The first
transistor comprises: a first terminal; a second terminal; and a
control terminal, for receiving a bias voltage generated from at
least operating voltage of the control circuit. The second
transistor comprises: a first terminal, coupled to a second
terminal of the first transistor; a second terminal, for receiving
a first predetermined voltage; and a control terminal, for
receiving the control voltage. The control circuit further
comprises: a candidate voltage selecting circuit, for outputting
one of a plurality of candidate voltages; and a voltage selecting
circuit, for outputting one of the candidate voltage output from
the candidate voltage selecting circuit and a ground voltage as the
bias voltage; wherein the candidate voltages are related with the
operating voltage of the control circuit and a predetermined
voltage; wherein the control circuit controls a target device
receiving the predetermined voltage.
[0009] Another embodiment of the present invention discloses a
power managing IC and a control IC. The power managing IC provides
a first predetermined voltage. The control IC, receives the first
predetermined voltage and comprises: at least one transistor; a
bias voltage receiving terminal, for receiving a bias voltage
generated from at least operating voltage of the control IC,
wherein the bias voltage is applied to bias at least one transistor
in the control IC. The control IC further comprises a core device
receiving a core voltage from the bias voltage receiving terminal,
wherein the bias voltage equals to the core voltage.
[0010] Another embodiment of the present invention discloses a
power managing IC and a control IC. The power managing IC provides
a first predetermined voltage. The control IC receives the first
predetermined voltage and comprises: at least one transistor; a
bias voltage receiving terminal, for receiving a bias voltage
generated from at least operating voltage of the control IC,
wherein the bias voltage is applied to bias at least one transistor
in the control IC. The bias voltage equals to the first
predetermined voltage minus the core voltage.
[0011] Another embodiment of the present invention discloses a
power managing IC and a control IC. The power managing IC provides
a first predetermined voltage. The control IC receives the first
predetermined voltage and comprises at least one transistor. The
control IC further receives a bias voltage generated from at least
operating voltage of the control IC, and the bias voltage is
applied to bias at least one transistor in the control IC. The
voltage generating circuit provides the bias voltage to the control
IC.
[0012] Another embodiment of the present invention discloses a
power managing IC and a control IC. The power managing IC provides
a first predetermined voltage. The control IC receives the first
predetermined voltage and comprises at least one transistor. The
control IC further receives a bias voltage generated from at least
operating voltage of the control IC, and the bias voltage is
applied to bias at least one transistor in the control IC. The bias
voltage is a ground voltage. The control IC further comprises: a
silicon die, wherein the transistor is provided in the silicon die;
and a package, comprising the silicon die. A ground voltage source
providing the ground voltage is located in the package and outside
the silicon die.
[0013] Another embodiment of the present invention discloses a
power managing IC and a control IC. The power managing IC provides
a first predetermined voltage. The control IC receives the first
predetermined voltage and comprises at least one transistor. The
control IC receives a bias voltage generated from at least
operating voltage of the control IC, and the bias voltage is
applied to bias at least one transistor in the control IC. The bias
voltage is aground voltage. The control IC further comprises: a
silicon die, wherein the transistor is provided in the silicon die;
and a package, comprising the silicon die. A ground voltage source
providing the ground voltage is located in the silicon die.
[0014] In view of above-mentioned embodiments, the driving circuit,
the control circuit and the control system can provide bias
voltages meeting different requirements, thus the applicability of
the driving circuit, the control circuit and the control system is
extended.
[0015] These and other objectives of the present invention will no
doubt become obvious to those of ordinary skill in the art after
reading the following detailed description of the preferred
embodiment that is illustrated in the various figures and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a circuit diagram illustrating a conventional
driving circuit.
[0017] FIG. 2 is a circuit diagram illustrating a control circuit
according to one embodiment of the present application.
[0018] FIG. 3A, FIG. 3B, FIG. 4-FIG. 8 are circuit diagrams
illustrating different examples for the embodiment illustrated in
FIG. 2.
[0019] FIG. 9 and FIG. 10 are examples for the driving circuit
illustrated in FIG. 2.
[0020] FIG. 11-FIG. 16 are block diagrams illustrating the control
system according to embodiments of the present application.
DETAILED DESCRIPTION
[0021] FIG. 2 is a circuit diagram illustrating a control circuit
200 according to one embodiment of the present application. As
illustrated in FIG. 2, the control circuit 200 comprises a core
unit 201 and a driving circuit-205. The core unit 201, which
receives and operates at a core voltage Vcore, is a device for
higher speed operations and lower voltage operations. Accordingly,
the core device can be applied as a circuit providing more
functions, such as a controller. Comparing with an I/O
(input/output) device applied for the input/output pad, the core
unit has thinner oxides.
[0022] The driving circuit 203 is a pull up module in this example,
which comprises a pull up circuit PUC (i.e. a voltage adjusting
circuit) for generating a control voltage CV (i.e. the pull up
signal PU in FIG. 1), a transistor TP1 and a transistor TP2. The
transistor TP1 and the transistor TP2 are PMOSFETs in this example.
The transistor TP1 comprises: a first terminal (drain terminal)
coupled to the input/output pad I/O; a second terminal (source
terminal); and a control terminal (gate terminal) for receiving a
bias voltage Vb generated from at least operating voltage of the
control circuit 200. The transistor TP2 comprises: a first terminal
(drain terminal), coupled to a second terminal of the first
transistor TP1; a second terminal (source terminal), for receiving
a predetermined voltage VDD; and a control terminal (gate
terminal), for receiving the control voltage CV.
[0023] In one embodiment, the predetermined voltage VDD meets one
of following specs: DDR3, DDR3L, LPDDR3, DDR4, LPDDR4, GPIO.
Corresponding to the spec, a value of the bias voltage Vb can equal
to the core voltage Vcore, the predetermined voltage minus the core
voltage VDD-Vcore, or a ground voltage GND. Please note either the
core voltage Vcore, the predetermined voltage minus the core
voltage VDD-Vcore or the ground voltage GND is an operating voltage
of the control circuit 200. Accordingly, the bias voltage Vb is
generated from the operating voltages of the control circuit
200.
[0024] The following table T1 depicts the examples of the
predetermined voltage VDD and the bias voltage Vb corresponding to
different specs. However, these values are only examples and do not
mean to limit the scope of the present application.
TABLE-US-00001 T1 VDD Vb Spec 1.5 V VDD-Vcore DDR3 1.35 V VDD-Vcore
or GND DDR3L 1.2 V GND LPDDR3/DDR4 1.1 V GND LPDDR4 1.8 V Vcore
GPIO
[0025] In this embodiment, the control circuit 200 further
comprises a pull down module 205, which can be regarded as a
driving circuit as well, comprising a pull down circuit PDC, which
is also as a voltage adjusting circuit, a transistor TN1 and a
transistor TN2. The transistor TN1 and the transistor TN2 are
NMOSFETs in this embodiment. Please note, in one embodiment, the
transistor TN1 receives the core voltage Vcore for biasing.
However, if the concept of the driving circuit 203 is applied to
the pull down module 205. The voltage received by the control
terminal of the transistor TN1 is replaced by a bias voltage
generated from the operating voltages of the control circuit 200.
In other embodiments, the driving circuit 203 may further comprise
other circuits such as a level shifter or a buffer located between
the core unit 201 and the pull up circuit PUC, or the pull down
module 205 comprises other circuits such as a level shifter or a
buffer located between the core unit 201 and the pull down circuit
PDC. Such variation should also fall in the scope of the present
application.
[0026] Please note, the driving circuit 203 is not limited to be
applied to the control circuit illustrated in FIG. 2. Accordingly,
a driving circuit provided by the present application can be
summarized as: A driving circuit, comprising a voltage adjusting
circuit (ex. the pull up circuit PUC for a pull up module 203, or
the pull down circuit PDC for the pull down module 205) for
generating a control voltage CV, comprising a first transistor (ex.
the transistor TP1 for a pull up module, or the transistor TN1 for
the pull down module 205) and a second transistor (ex. the
transistor TP2 for a pull up module, or the transistor TN2 for the
pull down module 205). The first transistor comprises: a first
terminal; a second terminal; and a control terminal, for receiving
a bias voltage (ex. Vb) generated from at least operating voltage
of the control circuit. The second transistor comprises: a first
terminal, coupled to a second terminal of the first transistor; a
second terminal, for receiving a predetermined voltage (ex. VDD);
and a control terminal, for receiving the control voltage (ex.
CV).
[0027] FIG. 3A, FIG. 3B, FIG. 4-FIG. 8 are circuit diagrams
illustrating different examples for the embodiment illustrated in
FIG. 2. These examples illustrate how to provide required bias
voltages. In the example of FIG. 3A, a bias voltage generating
circuit 301 is provided in the driving circuit 203. The biasing
circuit receives the predetermined voltage VDD and the core voltage
Vcore to generate a voltage equaling to the predetermined voltage
minus the core voltage VDD-Vcore as a bias voltage Vb. The core
voltage Vcore can come from the core unit 201 or an external source
outside the control circuit 200. Please note the bias voltage
generating circuit 301 can be incorporated into the pull up circuit
PUC (i.e. the voltage adjusting circuit), as shown in FIG. 3B. The
structure in FIG. 3B can also provide a bias voltage Vb equaling to
the core voltage Vcore. Please note if the bias voltage Vb equals
to the core voltage Vcore, it can be directly from the core unit,
as illustrated in FIG. 4.
[0028] In the embodiment of FIG. 5, the bias voltage Vb is from an
external source outside the control circuit 200, which will be
described later. In such case, the bias voltage can equal to the
ground voltage GND or VDD-Vcore. In the embodiment of FIG. 6, the
bias voltage Vb equals to a ground voltage GND, and the pull up
circuit PUC is also coupled to the ground voltage GND. In the
embodiment of FIG. 7, a multiplexer 701 is further provided in the
driving circuit 203 to select a required bias voltage from a
plurality of candidate voltages. In this example, candidate
voltages are the ground voltage GND and the core voltage Vcore, but
not limited.
[0029] Further, in the embodiment of FIG. 8, the driving circuit
further comprises a multiplexer 801 and a candidate voltage
selecting circuit 803. The candidate voltage selecting circuit 803
outputs one of a plurality of candidate voltages (in this example,
the core voltage Vcore, and the predetermined voltage minus the
core voltage VDD-Vcore). The multiplexer 801 outputs the candidate
voltage output from the candidate voltage selecting circuit 803 and
a second predetermined voltage (the ground voltage GND in this
example) as the bias voltage Vb. It will be appreciated that the
candidate voltages are also related with the operating voltage of
the control circuit.
[0030] The structure for the driving circuit is not limited to
above-mentioned embodiments. FIG. 9 and FIG. 10 are examples for
the driving circuit illustrated in FIG. 2. As shown in FIG. 9, the
driving circuit further comprises resistors R1 and R2, which are
coupled in series and coupled to the input/output pad I/O. In the
example of FIG. 10, the driving circuit comprises a resistor R3
coupled between the output terminal OT and the input/output pad
I/O. Such variation should also fall in the scope of the present
application.
[0031] The following embodiments will depict the above-mentioned
embodiments in a system view. As illustrated in FIG. 11, the
control system 1100 comprises a power managing IC (integrated
circuit) 1101 and a control IC 1103. The power managing IC 1101
comprises a power providing terminal Tpp for providing a
predetermined voltage VDD. The control IC 1103, which is applied to
control a target device 1111 (ex. a DRAM die), comprises: a power
receiving terminal Tpr for receiving the predetermined voltage VDD;
and a bias voltage receiving terminal Tbr, for receiving a bias
voltage Vb generated from at least operating voltage of the control
IC 1103. The bias voltage Vb is applied to bias at least one
transistor (ex. the transistor Tp1 in FIG. 2) in the control IC
1103.
[0032] In one embodiment, the control IC 1103 comprises a control
circuit 1105, which may comprise the same structure as which of the
control circuit 200 in FIG. 2. Accordingly, the control circuit
1105 receives the bias voltage Vb from the bias voltage receiving
terminal Tbr and receives the predetermined voltage VDD from the
power receiving terminal Tpr. In such embodiment, the control
circuit 1105 can comprise a core unit 1107 (ex. a DRAM controller)
and a driving circuit 1109, the same as the control circuit in FIG.
2. The core unit 1107 can be the same as the core unit 201 in FIG.
2, and the driving circuit 1107 can comprise a structure the same
as which of the driving circuit 203 in FIG. 2, but not limited.
Also, the control IC 1103 can further comprise a core voltage
receiving terminal Tcore to receive a core voltage Vcore from the
power managing IC 1101 and transmits the core voltage Vcore to the
control circuit 1105. Please note if the control IC 1103 does not
comprise the core unit 1107, the core voltage receiving terminal
Tcore can be omitted.
[0033] In the embodiment of FIG. 11, the control IC 1103 receives
the bias voltage Vb from the power managing IC 1101 (ex. the
embodiment in FIG. 5). In such case, the bias voltage Vb can equal
to the core voltage Vcore or the predetermined voltage minus the
core voltage VDD-Vcore.
[0034] In the embodiment of FIG. 12, the control IC 1103 does not
directly receive the bias voltage Vb from the power managing IC
1101. The power managing IC 1101 provides the core voltage Vcore to
either the core unit 1107 or the driving circuit 1109 via the core
voltage receiving terminal Tcore. In such case, the bias voltage
can equal to the core voltage Vcore or the predetermined voltage
minus the core voltage VDD-Vcore (ex. the embodiment in FIG. 3A or
FIG. 3B). In the case that the bias voltage equals to the core
voltage Vcore(ex. the embodiment in FIG. 5), the core voltage
receiving terminal Tcore can be regarded as a bias voltage
receiving terminal. However, in the case that the bias voltage
equals to the predetermined voltage minus the core voltage
VDD-Vcore, a bias generating circuit such as 301 in FIG. 3A is
needed.
[0035] In the embodiment of FIG. 13, the control IC 1103 does not
receive the bias voltage Vb from the power managing IC 1101. The
power managing IC 1101 provides the core voltage Vcore to the core
unit 1107 but not to the driving circuit 1109. In such case, the
driving circuit 1109 receives the core voltage Vcore from the core
unit 201 if needed. Also, the bias voltage can equal to the core
voltage Vcore or the predetermined voltage minus the core voltage
VDD-Vcore (ex. the embodiment in FIG. 3A or FIG. 3B. In the case
that the bias voltage equals to the core voltage Vcore, the core
voltage Vcore is directly applied as the bias voltage from the core
unit 1107. However, in the case that the bias voltage equals to the
predetermined voltage minus the core voltage VDD-Vcore, a bias
generating circuit such as 301 in FIG. 3A is needed.
[0036] If the bias voltage equals to a ground voltage GND, the bias
voltage receiving terminal Tbr can be coupled to a ground voltage
source providing the ground voltage. In one embodiment, the control
system 1100 is provided on a circuit board, and the ground voltage
source is located on the circuit board, as shown in FIG. 14. Also,
in one embodiment, the driving circuit 1109 is provided in a
silicon die, and the control IC 1103 is comprised in a package
comprising the silicon die, the power receiving terminal Tpr and
the bias voltage receiving terminal Tb. In such case, the ground
voltage source can be located in the package and outside the
silicon die, as shown in FIG. 15. Alternatively, the ground voltage
source can be located in the silicon die, as shown in FIG. 16.
[0037] The embodiments in FIG. 11-FIG. 16 can be applied to a 1.2v
CMOS logic device, following JESD 76-1 spec, or HSIC USB 2.0 spec,
but not limited.
[0038] In view of above-mentioned embodiments, the driving circuit,
the control circuit and the control system can provide bias
voltages meeting different requirements, thus the applicability of
the driving circuit, the control circuit and the control system is
extended.
[0039] Those skilled in the art will readily observe that numerous
modifications and alterations of the device and method may be made
while retaining the teachings of the invention. Accordingly, the
above disclosure should be construed as limited only by the metes
and bounds of the appended claims.
* * * * *