JP2006066984A - Output circuit and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an output circuit and a semiconductor device capable of preventing deterioration in distortion rate while reducing power consumption with respect to the output circuit for outputting an output signal corresponding to an input signal and the semiconductor device. <P>SOLUTION: The output circuits (100, 200) have output transistors (Mp0, Mn0) for outputting output currents corresponding to input signals (Vin-, Vin+). The circuits have idling current control means (110, 120; 210, 220) for performing control to cause an idling current to flow to the output transistors (Mp0, Mn0), respectively. The means (110, 120; 210, 220) control the idling current (Iidle) in response to an ambient temperature. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an output circuit and a semiconductor device, and more particularly to an output circuit and a semiconductor device that output an output signal corresponding to an input signal.

  FIG. 4 shows a circuit configuration diagram of an example of the prior art.

  The conventional output circuit 1 includes a first output transistor Mp0, a second output transistor Mn0, a first idling current control circuit 10, and a second idling current control circuit 20, and includes a cross-coupled feedforward class AB amplification. The circuit is configured.

  The first output transistor Mp0 is composed of a p-channel MOS field effect transistor, the source is connected to the power supply terminal Tvdd, the drain is connected to the output terminal Tout, and the gate is connected to the input terminal Tin−. The transistor Mp0 draws a current corresponding to the input voltage Vin− supplied to the input terminal Tin− from the power supply terminal Tvdd and supplies it to the output terminal Tout.

  The second output transistor Mn0 is composed of an n-channel MOS field effect transistor, and has a source connected to the ground terminal TGND, a drain connected to the output terminal Tout, and a gate connected to the input terminal Tin +. The transistor Mn0 draws a current corresponding to the input voltage Vin + supplied to the input terminal Tin + from the output terminal Tout and supplies the current to the terminal TGND.

  The first idling current control circuit 10 is a circuit for setting the idling current of the first output transistor Mp0, and includes current sources 11 and 12, and p-channel MOS field effect transistors Mp11, Mp12, and Mp13.

  The current source 11 is connected between the power supply terminal Tvdd and the input terminal Tin−, and supplies a current I1 to the source of the transistor Mp12 and the drain of the transistor Mn12. The current source 12 and the transistors Mp11 and Mp13 are connected in series between the power supply terminal Tvdd and the ground terminal TGND.

  The current source 12 draws a current I2 from the drain of the transistor Mp11. The transistor Mp13 has a configuration in which the gate and the drain are short-circuited, and the voltage between the power supply terminal Tvdd and the source of the transistor Mp12 is a constant voltage. The transistor Mp11 forms a current mirror circuit together with the transistor Mp12, controls the transistor Mp12 so that a current corresponding to the current flowing through the transistor Mp11 is drawn from the transistor Mp12, and controls the gate voltage of the transistor Mp0.

  The first idle current control circuit 10 controls the idling current Iidle supplied to the first output transistor Mp0 by controlling the gate voltage of the first output transistor Mp0 with the above configuration.

  In the first idling current control circuit 10, the idling current Iidle is determined by a loop formed by the first output transistor Mp0 and the transistors Mp11 to Mp13.

  The second idling current control circuit 20 is a circuit for setting the idling current of the second output transistor Mn0, and includes current sources 21 and 22 and n-channel MOS field effect transistors Mn11, Mn12, and Mn13.

  The current source 21 is connected between the ground terminal TGND and the input terminal Tin +, and draws the current I1 from the drain of the transistor Mp12 and the source of the transistor Mn12. The current source 22 and the transistors Mn11 and Mn13 are connected in series between the power supply terminal Tvdd and the ground terminal TGND.

  The current source 22 supplies a current I2 to the drain of the transistor Mn11. The transistor Mn13 has a configuration in which a gate and a drain are short-circuited, and a voltage between the ground terminal TGND and the source of the transistor Mn12 is a constant voltage. The transistor Mn11 forms a current mirror circuit together with the transistor Mn12, controls the transistor Mn12 so that a current corresponding to the current flowing through the transistor Mn11 is drawn from the transistor Mn12, and controls the gate voltage of the transistor Mn0.

  The second idle current control circuit 20 controls the idling current Iidle drawn by the second output transistor Mn0 by controlling the gate voltage of the second output transistor Mn0 with the above configuration.

  In the second idling current control circuit 20, the idling current Iidle is determined by a loop formed by the second output transistor Mn0 and the transistors Mn11 to Mn13.

  With the recent demand for low power consumption, it is desired to reduce idle current.

  As a method for reducing the idling current, an idling current adjusting circuit that detects no signal and reduces the idling current has been proposed (see Patent Document 1).

As a circuit similar in configuration to the circuit shown in FIG. 4, in order to reduce crossover distortion, one end of each main current path is commonly connected, and the common connection point of the main current path is connected to the output terminal of the circuit. First and second output transistors of different conductivity types connected to each other;
A main current is connected between the first and second signal lines connected to the respective control terminals of the first and second output transistors, and a signal on the first signal line. A first transistor that operates in response to a state;
A main current is connected between the first and second signal lines, and a second transistor that operates according to the signal state of the second signal line is provided, and the first transistor and the second transistor are complementarily symmetrical. A semiconductor integrated circuit that has been operated has been proposed (see Patent Document 2).

JP-A-4-330810 JP 2001-177352 A

  However, in the output circuit 1 having the configuration shown in FIG. 4, when the idle current is reduced to reduce power consumption, the distortion rate is degraded, and conversely, the idle current is increased to suppress the distortion rate degradation. If it does, the power consumption at the time of no signal will become large.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an output circuit and a semiconductor device that can prevent deterioration of distortion while reducing power consumption.

  In the present invention, in an output circuit (100, 200) having an output transistor (Mp0, Mn0) that outputs an output current corresponding to an input signal (Vin−, Vin +), an idling current flows through the output transistor (Mp0, Mn0). The idling current control means (110, 120; 210, 220) controls the idling current control means (110, 120; 210, 220) to control the idling current (Iidle) according to the ambient temperature. It is characterized by that.

  The idling current control means (110, 120) includes a constant voltage source (Mp13, Mn13), a constant current source (12, 22), a constant voltage source (Mp13, Mn13), and a constant current source (12, 22). Current mirror circuit (Mp11, Mp12; Mn11, Mn12), a constant voltage source (Mp13, Mn13) and a current mirror circuit that control the gate voltage of the output transistor (Mp0, Mn0) by a current according to the current flowing between (Mp11, Mp12; Mn11, Mn12) and having a resistance (R11, R12) whose resistance value changes so as to increase the idling current (Iidle) when the temperature rises. .

  As another configuration, the idling current control means (210, 220) includes a constant voltage source (Mp13, Mn13), a constant current source (12, 22), a constant voltage source (Mp13, Mn13), and a constant current source. Current mirror circuit (Mp11, Mp12; Mn11, Mn12) for controlling the gate voltage of the output transistor (Mp0, Mn0) by a current according to the current flowing between (12, 22) and the output transistor (Mp0, Mn0) Connected to the current mirror circuit (Mp11, Mp12; Mn11, Mn12), and resistors (R21, R22) whose resistance values change so as to increase the idling current (Iidle) when the temperature rises. It is characterized by having.

  Further, the resistors (R11, R12; R21, R22) are characterized by being composed of diffused resistors formed on the semiconductor substrate. Further, the resistors (R11, R12; R21, R22) are formed in the vicinity of the output transistors (Mp0, Mn0).

  In addition, the said reference code is a reference to the last, This does not limit a claim.

  According to the present invention, when the circuit is operated, the temperature of the circuit rises, thereby increasing the idling current, so that the distortion can be prevented from being deteriorated. When the circuit is stopped, the temperature of the circuit is lowered, thereby idling. It has features such as reduced current consumption due to reduced current.

[First embodiment]
〔Constitution〕
FIG. 1 shows a circuit configuration diagram of a first embodiment of the present invention. In the figure, the same components as those in FIG.

  The output circuit 100 of this embodiment is different from the output circuit 1 shown in FIG. 3 in the configuration of the first idling current control circuit 110 and the second idling current control circuit 120. The output circuit 100 of the present embodiment is formed on the same semiconductor substrate.

  The first idling current control circuit 110 according to the present embodiment has a configuration in which a resistor R11 is connected between the transistor Mp13 and the transistor Mp11. The second idling current control circuit 120 has a configuration in which a resistor R12 is connected between the transistor Mp13 and the transistor Mp11.

  The resistors R11 and R12 are both composed of diffused resistors and have a positive temperature characteristic.

  Further, the resistor R11 is disposed in the vicinity of the first output transistor Mp0 on the semiconductor substrate, and is disposed at a position susceptible to the temperature of the first output transistor Mp0. Further, the resistor R12 is disposed in the vicinity of the first output transistor Mn0 on the semiconductor substrate, and is disposed at a position susceptible to the temperature of the second output transistor Mn0.

[Operation]
[No signal]
When there is no signal, the idle current Iidle0 set by the current sources 11 and 21 flows to the first and second output transistors Mp0 and Mn0. At this time, unnecessary power consumption can be suppressed by setting the idle current Iidle0 to a sufficiently small value.

[During driving]
Next, the operation during driving will be described.

  When driving of the first output transistor Mp0 is started by the input voltage Vin−, a current corresponding to the input voltage Vin− is supplied from the first output transistor Mp0 to the load RL. At this time, a sufficiently large current flows through the first output transistor Mp0 compared to when the operation is stopped.

  When a current corresponding to the input voltage Vin− flows through the first output transistor Mp0, the first output transistor Mp0 generates heat and the ambient temperature rises. The resistor R11 is disposed in the vicinity of the first output transistor Mp0 and has a positive temperature characteristic. Therefore, when the temperature of the first output transistor Mp0 rises, its resistance value increases.

  When the resistance value of the resistor R11 increases, the source and gate potential of the transistor Mp11 decreases. Since the transistors Mp11 and Mp12 form a current mirror circuit, when the gate potential of the transistor Mp11 decreases, the gate potential of the transistor Mp12 also decreases.

  Since the transistor Mp12 controls the gate potential of the first output transistor Mp0, the gate potential of the transistor Mp12 decreases due to the decrease in the gate potential of the transistor Mp11, and the gate-source between the first output transistor Mp0. The potential increases.

  As the gate-source potential of the first output transistor Mp0 increases, the idling current Iidle supplied to the first output transistor Mp0 increases. By increasing the idling current Iidle, the distortion caused by the first output transistor Mp0 can be reduced.

  On the other hand, when the second output transistor Mn0 is driven by the input voltage Vin +, a current corresponding to the input voltage Vin + is drawn from the load RL to the second output transistor Mn0. At this time, a sufficiently large current flows through the second output transistor Mn0 compared to when the operation is stopped.

  When a current corresponding to the input voltage Vin + flows through the second output transistor Mn0, the second output transistor Mn0 generates heat and the ambient temperature rises. The resistor R12 is disposed in the vicinity of the second output transistor Mn0 and has a positive temperature characteristic. Therefore, when the temperature of the second output transistor Mn0 rises, its resistance value increases.

  As the resistance value of the resistor R12 increases, the source and gate potential of the transistor Mn11 decreases. Since the transistor Mn11 and the transistor Mp12 form a current mirror circuit, when the gate potential of the transistor Mn11 decreases, the gate potential of the transistor Mn12 also decreases.

  Since the transistor Mn12 controls the gate potential of the second output transistor Mn0, when the gate potential of the transistor Mn11 decreases, the gate potential of the transistor Mn12 decreases and the second output transistor Mn0 is connected between the gate and the source. The potential increases.

  As the gate-source potential of the second output transistor Mn0 increases, the idling current Iidle flowing through the second output transistor Mn0 increases. By increasing the idling current Iidle, distortion due to the second output transistor Mn0 can be reduced.

  FIG. 2 is a graph showing the characteristics of the idle current with respect to temperature in the first embodiment of the present invention.

  By giving the resistors R11 and R12 positive temperature characteristics, as shown in FIG. 2, the temperature of the first and second output transistors Mp0 and Mn0 rises, that is, the idle current Iidle increases when the driving state occurs. Can be made. When the first and second output transistors Mp0 and Mn0 are in the drive state, the distortion of the first and second output transistors Mp0 and Mn0 can be prevented from being deteriorated by increasing the idle current Iidle.

[Modification]
The resistors R11 and R12 are not limited to diffused resistors as long as they are resistance elements having positive temperature characteristics.

[Second Embodiment]
〔Constitution〕
FIG. 3 shows a circuit configuration diagram of the second embodiment of the present invention. In the figure, the same components as in FIG.

  The output circuit 200 of the present embodiment is different from the first embodiment in the configuration of the first idling current control circuit 210 and the second idling current control circuit 220.

  The first idling current control circuit 210 of the present embodiment is configured such that a resistor R21 is connected between the terminal Tin− and the drain of the transistor Mp12. The second idling current control circuit 220 is configured by connecting a resistor R22 between the terminal Tin + and the drain of the transistor Mp12.

  The resistors R21 and R22 are composed of diffused resistors like the resistors R11 and R12, and have a negative temperature characteristic.

  The resistor R11 is disposed in the vicinity of the first output transistor Mp0 on the semiconductor substrate, and is disposed at a position susceptible to the temperature of the first output transistor Mp0. The resistor R12 is disposed in the vicinity of the second output transistor Mn0 on the semiconductor substrate, and is disposed at a position that is easily influenced by the temperature of the second output transistor Mn0.

[Operation]
[No signal]
When there is no signal, the idle current Iidle0 set by the current sources 11 and 21 flows to the first and second output transistors Mp0 and Mn0. At this time, unnecessary power consumption can be suppressed by setting the idle current Iidle0 to a sufficiently small value.

[During driving]
Next, the operation during driving will be described.

  When the first output transistor Mp0 is driven by the input voltage Vin−, a current corresponding to the input voltage Vin− is supplied from the first output transistor Mp0 to the load RL. At this time, a sufficiently large current flows through the first output transistor Mp0 compared to when the operation is stopped.

  When a current corresponding to the input voltage Vin− flows through the first output transistor Mp0, the first output transistor Mp0 generates heat and the ambient temperature rises. The resistor R21 is disposed in the vicinity of the first output transistor Mp0 and has a negative temperature characteristic. Therefore, when the temperature of the first output transistor Mp0 rises, its resistance value decreases.

  When the resistance value of the resistor R21 decreases, the potential between the gate of the transistor Mp12 and the gate of the first output transistor Mp0 decreases, thereby increasing the gate-source potential of the first output transistor Mp0.

  As the gate-source potential of the first output transistor Mp0 increases, the idling current Iidle supplied to the first output transistor Mp0 increases. By increasing the idling current Iidle, the distortion caused by the first output transistor Mp0 can be reduced.

  On the other hand, when the second output transistor Mn0 is driven by the input voltage Vin +, a current corresponding to the input voltage Vin + is drawn from the load RL to the second output transistor Mn0. At this time, a sufficiently large current flows through the second output transistor Mn0 compared to when the operation is stopped.

  When a current corresponding to the input voltage Vin + flows through the second output transistor Mn0, the second output transistor Mn0 generates heat and the ambient temperature rises. The resistor R22 is disposed in the vicinity of the second output transistor Mn0 and has a negative temperature characteristic. Therefore, when the temperature of the second output transistor Mn0 rises, its resistance value decreases.

  When the resistance value of the resistor R22 decreases, the potential between the gate of the transistor Mn12 and the gate of the second output transistor Mn0 decreases, and the potential between the gate and source of the second output transistor Mn0 increases.

  As the gate-source potential of the second output transistor Mn0 increases, the idling current Iidle flowing through the second output transistor Mn0 increases. By increasing the idling current Iidle, distortion due to the second output transistor Mn0 can be reduced.

  By giving the resistors R21 and R22 negative temperature characteristics, as shown in FIG. 2, the temperature of the first and second output transistors Mp0 and Mn0 rises, that is, the idle current Iidle increases when the driving state occurs. Can be made. When the first and second output transistors Mp0 and Mn0 are in the drive state, the distortion of the first and second output transistors Mp0 and Mn0 can be prevented from being deteriorated by increasing the idle current Iidle.

[Modification]
The resistors R11 and R12 are not limited to diffused resistors as long as they are resistance elements having negative temperature characteristics.

It is a circuit block diagram of 1st Example of this invention. It is a figure which shows the characteristic of the idling current with respect to the temperature of 1st Example of this invention. It is a circuit block diagram of 2nd Example of this invention. It is a circuit block diagram of a conventional example.

Explanation of symbols

100 Output circuit 110, 210 First idling current control circuit 120, 220 Second idling current generation circuit 11, 12, 21, 22 Current source Mp0, Mp11, Mp12, Mp13 p-channel MOS field effect transistors Mn0, Mn11, Mn12 , Mn13 n-channel MOS field effect transistors R11, R12, R21, R22 resistance

Claims (11)

In an output circuit having an output transistor that outputs an output current according to an input signal,
An idling current control means for controlling the idling current to flow through the output transistor;
The output circuit according to claim 1, wherein the idling current control means controls the idling current according to an ambient temperature.   2. The output circuit according to claim 1, wherein the idling current control means controls an idling current to the output transistor by controlling a gate voltage of the output transistor. The idling current control means includes a constant voltage source,
A constant current source;
A current mirror circuit that controls a gate potential of the output transistor by a current corresponding to a current flowing between the constant voltage source and the constant current source;
3. The device according to claim 1, further comprising: a resistor connected between the constant voltage source and the current mirror circuit and having a resistance value that changes the idling current when the temperature rises. 4. Output circuit. The idling current control means includes a constant voltage source,
A constant current source;
A current mirror circuit that controls a gate potential of the output transistor by a current corresponding to a current flowing between the constant voltage source and the constant current source;
3. A resistor connected between the gate of the output transistor and the current mirror circuit, and having a resistance that changes so as to increase the idling current when the temperature rises. Output circuit.   5. The output circuit according to claim 4, wherein the resistance value of the resistor changes so as to increase the idling current when the temperature around the output transistor rises. In a semiconductor device having an output transistor that outputs an output current according to an input signal on a semiconductor substrate,
An idling current control means for controlling the idling current to flow through the output transistor;
The idling current control means controls the idling current according to an ambient temperature.   The semiconductor device according to claim 6, wherein the idling current control unit controls an idling current to the output transistor by controlling a gate voltage of the output transistor. The idling current control means includes a constant voltage source,
A constant current source;
A current mirror circuit that controls a gate potential of the output transistor by a current corresponding to a current flowing between the constant voltage source and the constant current source;
8. The device according to claim 6, further comprising: a resistor connected between the constant voltage source and the current mirror circuit, the resistance value of which changes so as to increase the idling current when the temperature rises. 9. Semiconductor device. The idling current control means includes a constant voltage source,
A constant current source;
A current mirror circuit that controls a gate potential of the output transistor by a current corresponding to a current flowing between the constant voltage source and the constant current source;
8. A resistor connected between the gate of the output transistor and the current mirror circuit and having a resistance value that changes so as to increase the idling current when the temperature rises. Semiconductor device.   10. The semiconductor device according to claim 8, wherein the resistor comprises a diffused resistor formed on the semiconductor substrate. 11.   The semiconductor device according to claim 8, wherein the resistor is formed in the vicinity of the output transistor.

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