Amplifier circuit
An amplifier circuit of the present disclosure includes: an input circuit that is configured to generate a differential current including a first current and a second current on the basis of an input signal; a first loop filter including a first former-stage integration circuit, a first inverter circuit, and a first latter-stage integration circuit, the first former-stage integration circuit configured to perform an integral action on the basis of the first current and a current corresponding to a first output signal, and the first latter-stage integration circuit that is configured to generate a first signal by receiving an output signal of the first inverter circuit and the first output signal and performing an integral action; a first modulation circuit; a first output circuit; a second loop filter including a second former-stage integration circuit, a second inverter circuit, and a second latter-stage integration circuit, the second former-stage integration circuit that receives the second current and a current corresponding to a second output signal and is configured to perform an integral action, and the second latter-stage integration circuit configured to generate a second signal by performing an integral action on the basis of an output signal of the second inverter circuit and the second output signal; a second modulation circuit; and a second output circuit.
1 . An amplifier circuit comprising:
an input circuit that is configured to generate a differential current including a first current and a second current on a basis of an input signal;
a first loop filter including a first former-stage integration circuit, a first inverter circuit, and a first latter-stage integration circuit, the first former-stage integration circuit configured to perform an integral action on a basis of the first current and a current corresponding to a first output signal, the first inverter circuit configured to invert an output signal of the first former-stage integration circuit, and the first latter-stage integration circuit configured to generate a first signal by performing an integral action on a basis of an output signal of the first inverter circuit and the first output signal;
a first modulation circuit that is configured to generate a first modulated signal by modulating the first signal with use of a predetermined signal;
a first output circuit that is configured to generate the first output signal on a basis of the first modulated signal;
a second loop filter including a second former-stage integration circuit, a second inverter circuit, and a second latter-stage integration circuit, the second former-stage integration circuit configured to perform an integral action on a basis of the second current and a current corresponding to a second output signal, the second inverter circuit configured to invert an output signal of the second former-stage integration circuit, and the second latter-stage integration circuit configured to generate a second signal by performing an integral action on a basis of an output signal of the second inverter circuit and the second output signal;
a second modulation circuit that is configured to generate a second modulated signal by modulating the second signal with use of the predetermined signal; and
a second output circuit that is configured to generate the second output signal on a basis of the second modulated signal.
2 . The amplifier circuit according to claim 1 , further comprising a negative resistor circuit that is configured to operate as a circuit having a negative resistance value, wherein
the input circuit causes the first current and the second current to flow into a first node and a second node,
the first former-stage integration circuit is coupled to the first node,
the second former-stage integration circuit is coupled to the second node, and
the negative resistor circuit is provided between the first node and the second node.
3 . The amplifier circuit according to claim 2 , wherein
the negative resistor circuit includes
a first terminal coupled to the first node,
a second terminal coupled to the second node,
a first transistor having a gate configured to be coupled to the first terminal, and a drain configured to be coupled to the second terminal, and
a second transistor having a gate configured to be coupled to the second terminal, and a drain configured to be coupled to the first terminal.
4 . The amplifier circuit according to claim 1 , further comprising:
a first circuit that is configured to generate a first feedback signal corresponding to an inverted signal of the first output signal;
a first high-pass filter that is configured to allow a high-frequency component of the first feedback signal to pass therethrough;
a second circuit that is configured to generate a second feedback signal corresponding to an inverted signal of the second output signal; and
a second high-pass filter that is configured to allow a high-frequency component of the second feedback signal to pass therethrough, wherein
the first former-stage integration circuit is configured to perform the integral action on a basis of the first current, the current corresponding to the first output signal, and an output current of the first high-pass filter, and
the second former-stage integration circuit is configured to perform the integral action on a basis of the second current, the current corresponding to the second output signal, and an output current of the second high-pass filter.
5 . The amplifier circuit according to claim 1 , wherein
the input circuit causes the first current and the second current to flow into a first node and a second node,
the first former-stage integration circuit includes
a first operational amplifier circuit having a positive input terminal, a negative input terminal coupled to the first node, and an output terminal,
a first capacitor having a first terminal coupled to the negative input terminal of the first operational amplifier circuit, and a second terminal coupled to the output terminal of the first operational amplifier circuit, and
a first resistor having a first terminal to be supplied with the first output signal, and a second terminal coupled to the negative input terminal of the first operational amplifier circuit, and
the second former-stage integration circuit includes
a second operational amplifier circuit having a positive input terminal, a negative input terminal coupled to the first node, and an output terminal,
a second capacitor having a first terminal coupled to the negative input terminal of the second operational amplifier circuit, and a second terminal coupled to the output terminal of the first operational amplifier circuit, and
a second resistor having a first terminal to be supplied with the second output signal, and a second terminal coupled to the negative input terminal of the second operational amplifier circuit.