Multistage amplifier circuit with improved settling time

A multistage amplifier circuit, comprising:

• a first forward circuit, including a first amplifier having a first amplifier input to receive an input signal, and a second amplifier having a second amplifier input coupled with an output of the first amplifier, the second amplifier including a second amplifier output providing an output signal;
• a second forward circuit, including a third amplifier having a third amplifier input coupled to receive the input signal, a fourth amplifier having a fourth amplifier input coupled with an output of the third amplifier, and a fifth amplifier having a fifth amplifier input coupled with an output of the fourth amplifier, the fifth amplifier having a fifth amplifier output coupled with the second amplifier input;
• a comparator circuit including a first comparator input coupled with a first differential input of the fourth amplifier, a second comparator input coupled with a second differential input of the fourth amplifier, and a comparator output providing a comparator output signal in a first state when a difference between voltages at the first and second comparator inputs exceeds a non-zero threshold indicative of nonlinear operation or slewing conditions in the multistage amplifier circuit, and in a second state when nonlinear operation or slewing conditions are not sensed in the multistage amplifier circuit;
• a compensation capacitance including a first terminal coupled to receive the second amplifier output signal, and a second terminal coupled with one of the first and second differential inputs of the fourth amplifier;
• and
• a clamp circuit coupled with the fourth amplifier input to selectively maintain a voltage at the second terminal of the compensation capacitance when the comparator output signal is in the first state.

A method comprising:

• providing an output signal at an output of a first forward circuit of a multistage amplifier circuit, the multistage amplifier circuit comprising the first forward circuit and a second forward circuit;
• sensing, by a sensor circuit, a first signal in the second forward circuit to detect nonlinear operation or slewing conditions in the multistage amplifier circuit, the sensor circuit configured to provide a sensor circuit output signal in a first state when nonlinear operation or slewing conditions are sensed in the multistage amplifier circuit and in a second state when nonlinear operation or slewing conditions are not sensed in the multistage amplifier circuit;
• and
• maintaining, in response to the sensor circuit output signal in the first state, an amplitude of a second signal within the second forward circuit at a given level for reducing a settling time of the multistage amplifier circuit.