Linear power supply circuit and vehicle
A linear power supply circuit includes: an output stage including a first and a second output transistor connected in parallel between an input terminal to which an input voltage is applied and an output terminal to which an output voltage is applied; a driver configured to drive the first and second output transistors according to the difference between a voltage based on the output voltage and a reference voltage; and a potential difference suppressor configured to suppress the potential difference between the control terminals of the first and second output transistors. The potential difference suppressor includes an operational amplifier. The non-inverting input terminal of the operational amplifier is connected to the control terminal of the first output transistor. The inverting input terminal and the output terminal of the operational amplifier are connected to the control terminal of the second output transistor. The operational amplifier includes a phase compensation element.
1 . A linear power supply circuit comprising:
an output stage including a first output transistor and a second output transistor connected in parallel with each other between an input terminal configured to have an input voltage applied thereto and an output terminal configured to have an output voltage applied thereto;
a driver configured to drive the first and second output transistors according to a difference between a voltage based on the output voltage and a reference voltage; and
a potential difference suppressor configured to suppress a potential difference between a control terminal of the first output transistor and a control terminal of the second output transistor,
wherein
the potential difference suppressor includes an operational amplifier,
a non-inverting input terminal of the operational amplifier is connected to the control terminal of the first output transistor,
an inverting input terminal and an output terminal of the operational amplifier are connected to the control terminal of the second output transistor, and
the operational amplifier includes a phase compensation element.
2 . The linear power supply circuit according to claim 1 , wherein
the operational amplifier includes an output-stage transistor constituting a source-follower output stage or an emitter-follower output stage,
the phase compensation element includes a resistor and a capacitor,
if the output-stage transistor constitutes a source-follower output stage, the resistor is connected to a drain of the output-stage transistor and the capacitor is connected between a gate and a source of the output-stage transistor, and
if the output-stage transistor constitutes an emitter-follower output stage, the resistor is connected to a collector of the output-stage transistor and the capacitor is connected between a base and an emitter of the output-stage transistor.
3 . The linear power supply circuit according to claim 1 , wherein
the operational amplifier has an input offset voltage.
4 . The linear power supply circuit according to claim 3 , wherein
the operational amplifier includes:
a first input differential pair transistor connected to the control terminal of the first output transistor;
a second input differential pair transistor connected to the control terminal of the second output transistor; and
a current mirror circuit configured to supply the first input differential pair transistor with a first current and to supply the second input differential pair transistor with a second current, which is a mirror current of the first current, and
the input offset voltage is produced as a result of either
the first and second input differential pair transistors both being MOS transistors and being given different channel width-to-channel length ratios or
the first and second currents being given different values.
5 . The linear power supply circuit according to claim 1 , further comprising:
a clamper circuit configured to clamp a voltage applied to the control terminal of the second output transistor.
6 . The linear power supply circuit according to claim 5 , wherein
the clamper circuit includes:
a voltage division circuit configured to produce a division voltage of a difference between the input voltage and a voltage applied to the control terminal of the first output transistor; and
a diode configured to have applied to an anode thereof the division voltage output from the voltage division circuit, the diode having a cathode thereof connected to the control terminal of the second output transistor.
7 . A vehicle comprising the linear power supply circuit according to claim 1 .
8 . A vehicle comprising the linear power supply circuit according to claim 2 .
9 . A vehicle comprising the linear power supply circuit according to claim 3 .
10 . A vehicle comprising the linear power supply circuit according to claim 4 .
11 . A vehicle comprising the linear power supply circuit according to claim 5 .
12 . A vehicle comprising the linear power supply circuit according to claim 6 .