CONTROL CIRCUIT AND DRIVING CIRCUIT

Provided is a control circuit that controls the amplitude by using a voltage regulator and that has improved accuracy in amplitude control. The control circuit includes a first voltage regulator and a second voltage regulator. The first voltage regulator in the control circuit generates one of a pair of voltages from a predetermined reference voltage and supplies the one of the pair of voltages to one of a power supply terminal and a ground terminal of a driver. In addition, the second voltage regulator generates the other of the pair of voltages from the one of the pair of voltages and supplies the other of the pair of voltages to the other of the power supply terminal and the ground terminal.

TECHNICAL FIELD

The present technology relates to a control circuit. In particular, the present technology relates to a control circuit and a driving circuit that use a voltage regulator.

BACKGROUND ART

In the related art, a transmission-side driving circuit of a communication interface often includes, in addition to a driver, a voltage regulator disposed in the driving circuit to control the amplitude of the driver. For example, there has been proposed a driving circuit that is provided with voltage regulators respectively on a power supply side and a ground side along with drivers (refer to PTL 1, for example). The power supply-side voltage regulator in this driving circuit generates a high-level output of the driver from a predetermined reference voltage. The ground-side voltage regulator generates a low-level output of the driver from the reference voltage.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

In the related art described above, the voltage regulator is disposed both on the power supply side and on the ground side to improve PSRR (Power Supply Rejection Ratio). However, in the driving circuit described above, input offset of an operational amplifier in the voltage regulator may vary the amplitude of an output signal from the driver. This variation may reduce accuracy achieved when the voltage regulator controls the amplitude.

The present technology has been created in view of the above-described circumstances, and an object of the present technology is to provide a control circuit that controls the amplitude with use of a voltage regulator, the control circuit having improved accuracy in amplitude control.

Solution to Problem

The present technology has been made to solve the above-described problem, and a first aspect provides a control circuit including a first voltage regulator that generates one of a pair of voltages from a predetermined reference voltage and supplies the one of the pair of voltages to one of a power supply terminal and a ground terminal of a driver, and a second voltage regulator that generates the other of the pair of voltages from the one of the pair of voltages and supplies the other of the pair of voltages to the other of the power supply terminal and the ground terminal. This configuration is effective in accurately controlling the amplitude.

In addition, in the first aspect, the first voltage regulator may generate a lower voltage of the pair of voltages, and the second voltage regulator may generate a higher voltage of the pair of voltages. This configuration is effective in generating a high voltage from a low voltage.

In addition, in the first aspect, the first voltage regulator may generate a higher voltage of the pair of voltages, and the second voltage regulator may generate a lower voltage of the pair of voltages. This configuration is effective in generating a low voltage from a high voltage.

In addition, in the first aspect, the control circuit may further include a reference voltage generating circuit that generates and supplies the reference voltage to the first voltage regulator. This configuration is effective in inputting the reference voltage to the first voltage regulator.

In addition, in the first aspect, the reference voltage generating circuit may generate the reference voltage by using a predetermined ground voltage as a reference. This configuration is effective in generating the reference voltage with use of the ground voltage as a reference.

In addition, in the first aspect, the reference voltage generating circuit may generate the reference voltage by using a predetermined power supply voltage as a reference. This configuration is effective in generating the reference voltage with use of the power supply voltage as a reference.

In addition, in the first aspect, the first voltage regulator may include a first operational amplifier that outputs the one of the pair of voltages, a first resistor interposed between one of a pair of input terminals of the first operational amplifier and the one of the power supply terminal and the ground terminal, and a second resistor connected at one end to the one of the pair of input terminals, and the other of the pair of input terminals may receive the reference voltage as input. This configuration is effective in amplifying the reference voltage.

In addition, in the first aspect, a predetermined ground voltage may be applied to the other end of the second resistor. This configuration is effective in forming a feedback circuit.

In addition, in the first aspect, a predetermined power supply voltage may be applied to the other end of the second resistor. This configuration is effective in forming a feedback circuit.

In addition, in the first aspect, the second voltage regulator may include a second operational amplifier that outputs the other of the pair of voltages, a third resistor interposed between one of a pair of input terminals of the second operational amplifier and the other of the power supply terminal and the ground terminal, and a fourth resistor connected at one end to the one of the pair of input terminals, and a voltage corresponding to the one of the pair of voltages may be applied to the other of the pair of input terminals. This configuration is effective in amplifying the one of the pair of voltages.

In addition, in the first aspect, the one of the pair of voltages may be applied to the other end of the fourth resistor. This configuration is effective in forming a feedback circuit.

In addition, in the first aspect, a predetermined power supply voltage may be applied to the other end of the fourth resistor. This configuration is effective in forming a feedback circuit.

In addition, a second aspect of the present technology provides a driving circuit including a driver, a first voltage regulator that generates one of a pair of voltages from a predetermined reference voltage and supplies the one of the pair of voltages to one of a power supply terminal and a ground terminal of the driver, and a second voltage regulator that generates the other of the pair of voltages from the one of the pair of voltages and supplies the other of the pair of voltages to the other of the power supply terminal and the ground terminal. This configuration is effective in outputting a signal having an accurately controlled amplitude.

DESCRIPTION OF EMBODIMENTS

Modes for implementing the present technology (hereinafter referred to as embodiments) will be described below. The description will be given in the following order.

1. First Embodiment (example in which a high-voltage-side voltage regulator generates a high voltage from a low voltage)

2. Second Embodiment (example in which a low-voltage-side voltage regulator generates a low voltage from a high voltage)

3. Example of Application to Mobile Body

1. First Embodiment

[Configuration Example of Interface Circuit]

FIG.1is a block diagram depicting a configuration example of an interface circuit according to an embodiment of the present technology. The interface circuit is a circuit for transmitting signals, and includes a transmission circuit100and a reception circuit300.

The transmission circuit100is a circuit that transmits signals, and includes a transmission signal generating section110and a driving circuit200.

The transmission signal generating section110generates signals to be transmitted. The transmission signal generating section110, for example, generates and supplies a differential signal to the driving circuit200via a signal line119.

The driving circuit200amplifies the differential signal supplied from the transmission signal generating section110and outputs the amplified differential signal to the transmission line209. The reception circuit300uses a receiver or the like to receive the differential signal from the driving circuit200.

[Configuration Example of Driving Circuit]

FIG.2is a block diagram depicting a configuration example of the driving circuit200according to the first embodiment of the present technology. The driving circuit200includes a control circuit210and a driver250.

The control circuit210controls the amplitude of an output signal from the driver250. The control circuit210includes a high-voltage-side voltage regulator220, a reference voltage generating circuit230, and a low-voltage-side voltage regulator240.

The driver250adjusts the amplitude of a differential signal VIN supplied from the transmission signal generating section110and outputs a resultant differential signal VOUT to the reception circuit300. A high voltage VREGH is input to a power supply terminal of the driver250. In addition, a low voltage VREGL lower than the high voltage VREGH is input to a ground terminal of the driver250. Note that the high voltage VREGH and the low voltage VREGL are an example of a pair of voltages described in the claims.

The reference voltage generating circuit230generates and supplies a predetermined reference voltage to the low-voltage-side voltage regulator240.

The low-voltage-side voltage regulator240generates a low voltage VREGL from the reference voltage and supplies the low voltage VREGL to the ground terminal of the driver250and the high-voltage-side voltage regulator220. Note that the low-voltage-side voltage regulator240is an example of a first voltage regulator described in the claims.

The high-voltage-side voltage regulator220uses the low voltage VREGL as a reference voltage to generate a high voltage VREGH from the reference voltage and supplies the high voltage VREGH to the power supply terminal of the driver250. Note that the high-voltage-side voltage regulator220is an example of a second voltage regulator described in the claims.

FIG.3is a circuit diagram depicting a configuration example of the driving circuit200according to the first embodiment of the present technology. The high-voltage-side voltage regulator220includes a current source221, a resistor222, an operational amplifier223, a pMOS (p-channel Metal Oxide Semiconductor) transistor224, a resistor225, and a variable resistor226.

The current source221and the resistor222are interposed in series between the power supply voltage and a node227. The node227is connected to the low-voltage-side voltage regulator240and receives, as input, the low voltage VREGL from the low-voltage-side voltage regulator240.

An inverting input terminal (−) of the operational amplifier223is connected to a connection node between the current source221and the resistor222. A voltage corresponding to the low voltage VREGL is input to the inverting input terminal (−).

The pMOS transistor224is interposed between the power supply voltage and the power supply terminal of the driver250. A gate of the pMOS transistor224is connected to an output terminal of the operational amplifier223.

The resistor225is connected at one end to a non-inverting input terminal (+) of the operational amplifier223and at the other end to the node227. The variable resistor226is interposed between the non-inverting input terminal (+) of the operational amplifier223and the power supply terminal of the driver250. Note that the operational amplifier223is an example of a second operational amplifier described in the claims. In addition, the variable resistor226is an example of a third resistor described in the claims, and the resistor225is an example of a fourth resistor described in the claims.

The reference voltage generating circuit230includes a current source232and a resistor231. The current source232and the resistor231are connected in series between the power supply voltage and the ground voltage.

In addition, the low-voltage-side voltage regulator240includes an operational amplifier241, an nMOS (n-channel MOS) transistor242, a resistor243, and a variable resistor244.

An inverting input terminal (−) of the operational amplifier241is connected to the connection node between the current source232and the resistor231. The voltage of the node is input to the inverting input terminal (−) as a reference voltage.

The nMOS transistor242is interposed between the ground terminal of the driver250and the ground voltage. A gate of the nMOS transistor242is connected to an output terminal of the operational amplifier241.

The power supply voltage is applied to one end of the resistor243, and the other end of the resistor243is connected to the non-inverting input terminal (+) of the operational amplifier241. The variable resistor244is interposed between the non-inverting input terminal (+) of the operational amplifier241and the ground terminal of the driver250. Note that the operational amplifier241is an example of a first operational amplifier described in the claims. In addition, the variable resistor244is an example of a first resistor described in the claims, and the resistor243is an example of a second resistor described in the claims.

In addition, the differential signal VOUT includes a positive-phase signal VOUT+ and a negative-phase signal VOUT− that have different phases. The driver250outputs one of the high voltage VREGH and the low voltage VREGL as the positive-phase signal VOUT+. When the positive-phase signal VOUT+ is at the high voltage VREGH, the negative-phase signal VOUT− is set to the low voltage VREGL. When the positive-phase signal VOUT+ is at the low voltage VREGL, the negative-phase signal VOUT− is set to the high voltage VREGH.

Note that differential signals are input to and output from the driver250but that single-end signals can be input to and output from the driver250.

In the circuit configuration illustrated inFIG.3, the reference voltage generating circuit230generates a reference voltage by using the ground voltage as a reference. For example, when the resistor231is assumed to have a resistance value R1and the current source232is assumed to have a current value I, a voltage that is higher than the ground voltage by I×R1is generated as a reference voltage.

In addition, the low-voltage-side voltage regulator240amplifies the reference voltage by using a gain G1, and outputs the amplified voltage as the low voltage VREGL. Here, the gain G1is expressed by the following equation.

In the above equation, R4is the resistance value of the variable resistor244. R3is the resistance value of the resistor243.

The gain G2can be adjusted by changing the resistance value of the variable resistor244according to Equation 1.

Here, the operational amplifier241may be subjected to input offset ofs1due to variation among elements in the operational amplifier223. In view of the input offset ofs1, the low voltage VREGL is expressed by the following equation.

In the above equation, the terms of the low voltage VREGL, IR1, and the input offset ofs1are in units of, for example, millivolts (mV).

In addition, the high-voltage-side voltage regulator220amplifies a voltage corresponding to the low voltage VREGL by using a gain G2, and outputs the amplified voltage as the low voltage VREGL. Here, the gain G2is expressed by the following equation.

In the above equation, R6is the resistance value of the variable resistor266. R5is the resistance value of the resistor225.

The gain G2can be adjusted by changing the resistance value of the variable resistor226according to Equation 3.

In view of an input offset ofs2of the operational amplifier223, the high voltage VREGH is expressed by the following equation.

In the above equation, the terms of the high voltage VREGH and the input offset ofs2are in units of, for example, millivolts (mV).

In addition, an amplitude A of an output from the driver250is expressed by the following equation.

By substituting Equations 2 and 4 into Equation 5, and transforming the resultant equation, the following equations are obtained.

VREG in Equation 6 is the amplitude obtained in a case where no input offset occurs, and ΔVREG is variation in amplitude caused by input offset. The ratio between VREG and ΔVREG is expressed by the following equation on the basis of Equations 7 and 8.

Here, when the gain G2is assumed to be “1,” the following equation is obtained from Equation 9.

For example, when VREG is assumed to be 450 millivolts (mV) and the input offset ofs2is assumed to be 5 millivolts (mV), the amplitude varies approximately 1.1% on the basis of Equation 10. Note that, in a case where a gain G2is other than “1,” the term of the input offset ofs1remains but that, even in this case, the input offset ofs1has a low impact compared to the input offset ofs2.

Equation 10 indicates that, by using a configuration in which the high-voltage-side voltage regulator220references the low voltage VREGL and generates the high voltage VREGH from the low voltage VREGL, variation in amplitude that is caused by the offset ofs1of the operational amplifier241can be reduced. Thus, accuracy achieved when the control circuit210controls the amplitude can be improved.

Here, as a comparative example, assumed is a configuration in which the high-voltage-side voltage regulator220and the low-voltage-side voltage regulator240use an identical reference voltage.

FIG.4is a circuit diagram depicting a configuration example of the driving circuit200according to a comparative example. In the high-voltage-side voltage regulator220in the comparative example, the input-side node227is not connected to the low-voltage-side voltage regulator240but is connected to the reference voltage generating circuit.

In addition, in the comparative example, the low-voltage-side voltage regulator240is further provided with a resistor245and a current source246. The resistor245and the current source246are connected in series between a node247to which the reference voltage is supplied and the ground voltage. In addition, one end of the resistor243is connected to the node247instead of to the power supply voltage.

In the comparative example, the reference voltage generating circuit230uses a resistive divider circuit or an operational amplifier to supply a reference voltage VREF expressed by the following equation.

In the above equation, VDD is the power supply voltage, and ofs is the input offset of the operational amplifier in the reference voltage generating circuit. When the resistor245has a resistance value of R1similarly to the resistor231, the low voltage VREGL is expressed by the following equation on the basis of Equation 11.

In addition, the high voltage VREGH is expressed by the following equation on the basis of Equation 11.

Equations 12 and 13 provide the following equation.

When the gains G1and G2are each assumed to be “1,” VREG is assumed to be 450 millivolts (mV), and the input offsets ofs1and ofs2are each assumed to be 5 millivolts (mV), the amplitude varies approximately 2.2% on the basis of Equation 14.

As illustrated in Equations 9 and 14, in a case where the high-voltage-side voltage regulator220references the low voltage VREGL, the impact of ofs1can be canceled. In contrast, in the comparative example in which the high-voltage-side voltage regulator220does not reference the low voltage VREGL, the impact of ofs1fails to be canceled. Consequently, the latter involves a larger variation in amplitude caused by the offset voltage.

FIG.5is a circuit diagram depicting a configuration example of the high-voltage-side voltage regulator220with a different feedback circuit according to the first embodiment of the present technology. As illustrated inFIG.5, the power supply voltage can be applied to the other end of the resistor225. This connection allows the feedback circuit on the high voltage side to be changed compared to the configuration inFIG.3.

FIG.6is a circuit diagram depicting a configuration example of the reference voltage generating circuit230using the ground voltage as a reference and the low-voltage-side voltage regulator240with a different feedback circuit according to the first embodiment of the present technology.

FIG.7is a circuit diagram depicting a configuration example of the reference voltage generating circuit230using the power supply voltage as a reference and the low-voltage-side voltage regulator240with the different feedback circuit according to the first embodiment of the present technology.

As illustrated inFIGS.6and7, the ground voltage can be applied to the other end of the resistor243. This connection allows the feedback circuit on the low voltage side to be changed compared to the configuration inFIG.3.

In addition, the reference voltage generating circuit230can generate a reference voltage by using the ground voltage as a reference as illustrated inFIG.6or by using the power supply voltage as a reference as illustrated inFIG.7. In a case where the ground voltage is used as a reference, a voltage that is higher than the ground voltage by a predetermined voltage is supplied as the reference voltage, for example. In a case where the power supply voltage is used as a reference, a voltage that is lower than the power supply voltage by a predetermined voltage is supplied as the reference voltage, for example.

FIG.8is a circuit diagram depicting a configuration example of the reference voltage generating circuit230using the ground voltage as a reference and the low-voltage-side voltage regulator240according to the first embodiment of the present technology.

FIG.9is a circuit diagram depicting a configuration example of the reference voltage generating circuit230using the power supply voltage as a reference and the low-voltage-side voltage regulator240according to the first embodiment of the present technology.

The circuits of the low-voltage-side voltage regulators240inFIGS.8and9are similar to that depicted inFIG.3. The reference voltage generating circuit230connected to the low-voltage-side voltage regulator240can use the ground voltage as a reference as illustrated inFIG.8or use the power supply voltage as a reference as illustrated inFIG.9.

FIG.10is a diagram depicting an example of the waveform of an output signal in the first embodiment of the present technology and in the comparative example. InFIG.10, “a” is a diagram depicting an example of the waveform of an output signal from the driver250in the first embodiment of the present technology. InFIG.10, “b” is a diagram depicting an example of the waveform of an output signal from the driver250in the comparative example in which the high-voltage-side voltage regulator220does not reference the low voltage VREGL. In FIG.10, solid lines indicate the waveform of the high voltage VREGH, and alternate long and short dash lines indicate the waveform of the low voltage VREGL.

As illustrated in “a” ofFIG.10, in a case where the high-voltage-side voltage regulator220references the low voltage VREGL, when the control circuit210starts control at timing TO, the high voltage VREGH and the low voltage VREGL gradually rise. Then, the difference between the high voltage VREGH and the low voltage VREGL (that is, the amplitude) has a constant value.

In addition, as illustrated in “b” ofFIG.10, in the comparative example in which the high-voltage-side voltage regulator220does not reference the low voltage VREGL, when the control circuit210starts control at timing TO, the high voltage VREGH gradually lowers. On the other hand, the low voltage VREGL gradually rises. Then, the difference between the high voltage VREGH and the low voltage VREGL (that is, the amplitude) has a constant value. As illustrated in “b” ofFIG.10, in the comparative example, a signal with an amplitude larger than a defined value may accidentally be transmitted to the reception side. On the other hand, as illustrated in “a” ofFIG.10, no signal with an amplitude larger than the defined value is transmitted in the configuration in which the high-voltage-side voltage regulator220references the low voltage VREGL.

Thus, according to the first embodiment of the present technology, the high-voltage-side voltage regulator220generates the high voltage VREGH from the low voltage VREGL, allowing suppression of the input offset ofs1, which occurs on the low voltage side. This enables reduction in variation in amplitude caused by the input offset ofs1, allowing improvement of accuracy achieved when the control circuit210controls the amplitude.

2. Second Embodiment

In the first embodiment described above, the high-voltage-side voltage regulator220references the low voltage VREGL. However, in this configuration, in a case where the input offset ofs2on the high voltage side is relatively large, the accuracy of the control of the amplitude may be reduced. The driving circuit200of the second embodiment differs from the driving circuit200of the first embodiment in that the low-voltage-side voltage regulator240references the high voltage VREGH.

FIG.11is a block diagram depicting a configuration example of the driving circuit200according to the second embodiment of the present technology. In the driving circuit200of the second embodiment, the reference voltage generating circuit230supplies the reference voltage to the high-voltage-side voltage regulator220. The high-voltage-side voltage regulator220generates the high voltage VREGH from the reference voltage, and supplies the high voltage VREGH to the power supply terminal of the driver250and to the low-voltage-side voltage regulator240. In addition, the low-voltage-side voltage regulator240uses the high voltage VREGH as a reference voltage to generate the low voltage VREGL from the reference voltage, and supplies the low voltage VREGL to the ground terminal of the driver250.

Instead of Equation 10, the configuration inFIG.11provides the following equation.

Note that the high-voltage-side voltage regulator220is an example of the first voltage regulator described in the claims. In addition, the low-voltage-side voltage regulator240is an example of the second voltage regulator described in the claims.

As illustrated inFIG.2andFIG.11, the high-voltage-side voltage regulator220can reference the low voltage VREGL, and the low-voltage-side voltage regulator240can reference the high voltage VREGH.

Equations 10 and 15 indicate that the configuration inFIG.2is desirably used in a case where the input offset ofs1on the low voltage side is relatively large. On the other hand, the configuration inFIG.11is desirably used in a case where the input offset ofs2on the high voltage side is relatively large.

FIG.12is a circuit diagram depicting a configuration example of the reference voltage generating circuit230using the ground voltage as a reference and the high-voltage-side voltage regulator220according to the second embodiment of the present technology. The high-voltage-side voltage regulator220of the second embodiment differs from the high-voltage-side voltage regulator220in the first embodiment in that the current source221and the resistor222are not disposed in the high-voltage-side voltage regulator220of the second embodiment. In addition, the inverting input terminal (−) of the operational amplifier223receives, as input, the reference voltage from the reference voltage generating circuit230. The non-inverting input terminal (+) of the operational amplifier223is connected to the connection node between the resistor225and the variable resistor226. The resistor225is connected at one end to the non-inverting input terminal (+), and the ground voltage is applied to the other end of the resistor225.

FIG.13is a circuit diagram depicting a configuration example of the reference voltage generating circuit230using the power supply voltage as a reference and the high-voltage-side voltage regulator220according to the second embodiment of the present technology.

The reference voltage generating circuit230can generate a reference voltage by using the ground voltage as a reference as illustrated inFIG.12or by using the power supply voltage as a reference as illustrated inFIG.13.

FIG.14is a circuit diagram depicting a configuration example of a reference voltage generating circuit using the ground voltage as a reference and the high-voltage-side voltage regulator with a different feedback circuit according to the second embodiment of the present technology.

FIG.15is a circuit diagram depicting a configuration example of the reference voltage generating circuit using the power supply voltage as a reference and the high-voltage-side voltage regulator with the different feedback circuit according to the second embodiment of the present technology.

As illustrated inFIGS.14and15, the power supply voltage can also be applied to the other end of the resistor225. This connection allows the feedback circuit of the operational amplifier223to be changed compared to the configurations inFIGS.12and13.

In addition, the reference voltage generating circuit230can generate a reference voltage by using the ground voltage as a reference as illustrated inFIG.14or by using the power supply voltage as a reference as illustrated inFIG.15.

FIG.16is a circuit diagram illustrating a configuration example of the low-voltage-side voltage regulator240according to the second embodiment of the present technology. The low-voltage-side voltage regulator240of the second embodiment differs from the low-voltage-side voltage regulator240of the first embodiment in that the resistor245and the current source246are further disposed in the low-voltage-side voltage regulator240of the second embodiment.

The resistor245and the current source246are connected in series between the node247to which the high voltage VREGH is input and the ground voltage. In addition, the inverting input terminal (−) of the operational amplifier241is connected to the connection node between the resistor245and the current source246. The non-inverting input terminal (+) of the operational amplifier241is connected to the connection node between the resistor243and the variable resistor244. The resistor243is connected at one end to the non-inverting input terminal (+) and at the other end to the node247.

FIG.17is a circuit diagram of a configuration example of the low-voltage-side voltage regulator240with a different feedback circuit according to the second embodiment of the present technology. As illustrated inFIG.17, the ground voltage can be applied to the other end of the resistor243.

As described above, according to the second embodiment of the present technology, the low-voltage-side voltage regulator240generates the low voltage VREGL from the high voltage VREGH, allowing suppression of the input offset ofs2, which occurs on the high voltage side. This enables reduction in variation in amplitude caused by the input offset ofs2, allowing improvement of accuracy achieved when the control circuit210controls the amplitude.

<3. Example of Application to Mobile Body>

The technology according to the present disclosure (present technology) can be applied to various products. For example, the technology according to the present technology may be implemented as an apparatus mounted in any type of mobile bodies such as an automobile, an electric automobile, a hybrid electric automobile, a motor cycle, a bicycle, a personal transporter, an airplane, a drone, a ship, or a robot.

An example of the vehicle control system to which the technology according to the present disclosure can be applied has been described. The technology according to the present disclosure can be applied to the imaging section12031of the configuration described above. Specifically, the transmission circuit100inFIG.1can be applied to the communication interface of the imaging section12031. By application of the technology according to the present disclosure to the imaging section12031, the control accuracy for the amplitude is improved, allowing signal quality to be improved.

Note that the above-described embodiments are illustrated as examples for embodying the present technology, and the elements of the embodiments respectively have correspondence relations with specific elements of the invention described in the claims. Similarly, the specific elements of the invention described in the claims respectively have correspondence relations with the elements of the embodiments of the present technology having the same names as those of the specific elements. However, the present technology is not limited to the embodiments and can be embodied by making various modifications to the embodiments without departing from the spirits of the present technology.

Note that the effects described herein are only illustrative and not restrictive and that the present technology may produce any other effects.

Note that the present technology can also be configured as follows.

A control circuit including:

a first voltage regulator that generates one of a pair of voltages from a predetermined reference voltage and supplies the one of the pair of voltages to one of a power supply terminal and a ground terminal of a driver; and

a second voltage regulator that generates the other of the pair of voltages from the one of the pair of voltages and supplies the other of the pair of voltages to the other of the power supply terminal and the ground terminal.

The control circuit according to (1) described above, in which

the first voltage regulator generates a lower voltage of the pair of voltages, and

the second voltage regulator generates a higher voltage of the pair of voltages.

The control circuit according to (1) described above, in which

the first voltage regulator generates a higher voltage of the pair of voltages, and

the second voltage regulator generates a lower voltage of the pair of voltages.

The control circuit according to any one of (1) to (3) described above, further including:

a reference voltage generating circuit that generates and supplies the reference voltage to the first voltage regulator.

The control circuit according to (4) described above, in which

the reference voltage generating circuit generates the reference voltage by using a predetermined ground voltage as a reference.

The control circuit according to (4) described above, in which

the reference voltage generating circuit generates the reference voltage by using a predetermined power supply voltage as a reference.

The control circuit according to any one of (1) to (6) described above, in which

the first voltage regulator includesa first operational amplifier that outputs the one of the pair of voltages,a first resistor interposed between one of a pair of input terminals of the first operational amplifier and the one of the power supply terminal and the ground terminal, anda second resistor connected at one end to the one of the pair of input terminals, and

the other of the pair of input terminals receives the reference voltage as input.

The control circuit according to (7) described above, in which

a predetermined ground voltage is applied to the other end of the second resistor.

The control circuit according to (7) described above, in which

a predetermined power supply voltage is applied to the other end of the second resistor.

The control circuit according to (7) described above, in which

the second voltage regulator includesa second operational amplifier that outputs the other of the pair of voltages,a third resistor interposed between one of a pair of input terminals of the second operational amplifier and the other of the power supply terminal and the ground terminal, anda fourth resistor connected at one end to the one of the pair of input terminals, and

a voltage corresponding to the one of the pair of voltages is applied to the other of the pair of input terminals.

The control circuit according to (10) described above, in which

the one of the pair of voltages is applied to the other end of the fourth resistor.

The control circuit according to (10) described above, in which

a predetermined power supply voltage is applied to the other end of the fourth resistor.

A driving circuit including:

a driver;

a first voltage regulator that generates one of a pair of voltages from a predetermined reference voltage and supplies the one of the pair of voltages to one of a power supply terminal and a ground terminal of the driver; and

a second voltage regulator that generates the other of the pair of voltages from the one of the pair of voltages and supplies the other of the pair of voltages to the other of the power supply terminal and the ground terminal.

REFERENCE SIGNS LIST

100: Transmission circuit

110: Transmission signal generating section

200: Driving circuit

210: Control circuit

221,232,246: Current source

230: Reference voltage generating circuit

300: Reception circuit

12031: Imaging section