Operational amplifier, integrating circuit, feedback amplifier, and controlling method of the feedback amplifier
An operational amplifier according to an embodiment of the present invention includes: an operational amplifier stage executing differential-amplification of an input voltage and a reference voltage; a source-grounded amplifier stage outputting the differential-amplified signal; a phase compensation capacitance compensating for a phase of an output signal; and a charge/discharge control circuit controlling charge/discharge of the phase compensation capacitance.
1. An operational amplifier comprising:
an operational amplifier circuit differential-amplifying an input signal with reference to a reference potential;
an output circuit outputting the differential-amplified signal;
a phase compensation capacitance connected between an output of the operational amplifier circuit and an output of the output circuit and compensating for a phase of a signal output from the output circuit; and
a charge/discharge control circuit controlling charge/discharge of the phase compensation capacitances,
wherein the charge/discharge control circuit includes a first switching circuit turned ON/OFF for connection/disconnection between a node on the other end side of the phase compensation capacitance and a terminal for the reference potential.
2. The operational amplifier according to claim 1 , wherein the charge/discharge control circuit changes a potential at both ends or one end of the phase compensation capacitance to cause a predetermined potential difference between both the ends of the phase compensation capacitance to charge/discharge the phase compensation capacitance.
3. The operational amplifier according to claim 2 , wherein the predetermined potential difference is a difference between a power supply potential or a ground potential and the reference potential.
4. The operational amplifier according to claim 2 , wherein the predetermined potential difference is a difference between an output potential of the operational amplifier circuit with the operational amplifier in voltage follower connection, and a reference potential of the operational amplifier.
5. The operational amplifier according to claim 1 , wherein the node on the other end side connected with the first switching circuit is a node on an output side of the output circuit.
6. The operational amplifier according to claim 1 , wherein the charge/discharge control circuit includes a second switching circuit turned ON/OFF for connection/disconnection between a node on one end side of the phase compensation capacitance and a terminal for a power supply potential or a ground potential.
7. The operational amplifier according to claim 1 , wherein the charge/discharge control circuit includes a second switching circuit turned ON/OFF for connection/disconnection between a terminal applying a potential equal to an output potential of the operational amplifier circuit with the operational amplifier in voltage follower connection, and a node on one end side of the phase compensation capacitance.
8. The operational amplifier according to claim 6 , wherein the node on the one end side connected with the second switching circuit is a node on an output side of the operational amplifier circuit.
9. An operational amplifier comprising:
an operational amplifier circuit differential-amplifying an input signal with reference to a reference potential;
an output circuit outputting the differential-amplified signal;
a phase compensation capacitance connected between an output of the operational amplifier circuit and an output of the output circuit and compensating for a phase of a signal output from the output circuit;
a charge/discharge control circuit controlling charge/discharge of the phase compensation capacitance; and
a phase compensation resistor connected between the phase compensation capacitance and the operational amplifier circuit,
wherein the charge/discharge control circuit includes a second switching circuit turned ON/OFF for connection/disconnection between a node on one end side of the phase compensation capacitance and a terminal for a power supply potential or a ground potential, and
wherein the node on one end side connected with the second switching circuit is a node on an output side of the operational amplifier circuit and is disposed between the phase compensation capacitance and the phase compensation resistor.
10. An operational amplifier comprising:
an operational amplifier circuit differential-amplifying an input signal with reference to a reference potential;
an output circuit outputting the differential-amplified signal;
a phase compensation capacitance connected between an output of the operational amplifier circuit and an output of the output circuit and compensating for a phase of a signal output from the output circuit;
a charge/discharge control circuit controlling charge/discharge of the phase compensation capacitance; and
a phase compensation resistor connected between the phase compensation capacitance and the operational amplifier circuit,
wherein the charge/discharge control circuit includes a second switching circuit turned ON/OFF for connection/disconnection between a node on one end side of the phase compensation capacitance and a terminal for a power supply potential or a ground potential,
wherein the node on one end side connected with the second switching circuit is a node on an output side of the operational amplifier circuit and is disposed between the phase compensation resistor and the operational amplifier circuit.
11. The operational amplifier according to claim 1 , further comprising:
a first input terminal applying the reference potential;
a second input terminal inputting the input signal;
a buffer circuit amplifying and outputting a signal output from the output circuit;
a third switching circuit turned ON/OFF for connection/disconnection between a signal source of the input signal and the second input terminal; and
a reset switch connected between the second input terminal and an output of the buffer circuit.
12. An integrating circuit, comprising:
an operational amplifier;
an integral capacitance parallel-connected with the operational amplifier; and
a reset switch parallel-connected with the integral capacitance,
the operational amplifier including:
an operational amplifier circuit differential-amplifying an input signal with reference to a reference potential;
an output circuit outputting the differential-amplified signal;
a phase compensation capacitance connected between an output of the operational amplifier circuit and an output of the output circuit and compensating for a phase of a signal output from the output circuit; and
a charge/discharge control circuit controlling charge/discharge of the phase compensation capacitances,
wherein the charge/discharge control circuit includes a first switching circuit turned ON/OFF for connection/disconnection between a node on the other end side of the phase compensation capacitance and a terminal for the reference potential.
13. The integrating circuit according to claim 12 , wherein the charge/discharge control circuit changes a potential at both ends or one end of the phase compensation capacitance to cause a predetermined potential difference between both the ends of the phase compensation capacitance to charge/discharge the phase compensation capacitance.
14. A feedback amplifier, comprising:
an operational amplifier;
a feedback element parallel-connected with the operational amplifier; and
a reset switch parallel-connected with the feedback element,
the operational amplifier including:
an operational amplifier circuit differential-amplifying an input signal with reference to a reference potential;
an output circuit outputting the differential-amplified signal;
a phase compensation capacitance connected between an output of the operational amplifier circuit and an output of the output circuit and compensating for a phase of a signal output from the output circuit; and
a charge/discharge control circuit controlling charge/discharge of the phase compensation capacitance,
wherein the charge/discharge control circuit includes a first switching circuit turned ON/OFF for connection/disconnection between a node on the other end side of the phase compensation capacitance and a terminal for the reference potential.
15. The feedback amplifier according to claim 14 , wherein the charge/discharge control circuit changes a potential at both ends or one end of the phase compensation capacitance to cause a predetermined potential difference between both the ends of the phase compensation capacitance to charge/discharge the phase compensation capacitance.
16. The integrating circuit according to claim 12 , wherein the charge/discharge control circuit includes a second switching circuit turned ON/OFF for connection/disconnection between a node on one end side of the phase compensation capacitance and a terminal for a power supply potential or a ground potential.
17. The integrating circuit according to claim 12 , wherein the charge/discharge control circuit includes a second switching circuit turned ON/OFF for connection/disconnection between a terminal applying a potential equal to an output potential of the operational amplifier circuit with the operational amplifier in voltage follower connection, and a node on one end side of the phase compensation capacitance.
18. The feedback amplifier according to claim 14 , wherein the charge/discharge control circuit includes a second switching circuit turned ON/OFF for connection/disconnection between a node on one end side of the phase compensation capacitance and a terminal for a power supply potential or a ground potential.
19. The feedback amplifier according to claim 14 , wherein the charge/discharge control circuit includes a second switching circuit turned ON/OFF for connection/disconnection between a terminal applying a potential equal to an output potential of the operational amplifier circuit with the operational amplifier in voltage follower connection, and a node on one end side of the phase compensation capacitance.