Chopper-stabilized instrumentation amplifier

A physiological sensing device comprising:

• a physiological sensor that generates an input signal indicative of a physiological condition;
• and
• a chopper-stabilized instrumentation amplifier comprising:
• a first modulator that modulates an amplitude of the input signal at a clock frequency to produce a modulated signal;
• a mixer amplifier that amplifies the modulated signal to produce an amplified signal and demodulates the amplified signal at the clock frequency to produce an output signal;
• an input capacitor that couples the modulated signal to an input of the mixer amplifier;
• a second modulator that modulates an amplitude of the output signal at the clock frequency to produce a modulated output signal;
• and
• a feedback path that applies the modulated output signal as a feedback signal to the modulated signal at a node between the input capacitor and an input of the mixer amplifier via a feedback capacitor.

A chopper-stabilized instrumentation amplifier comprising:

• means for modulating an amplitude of an input signal at a clock frequency to produce a modulated signal;
• means for amplifying the modulated signal to produce an amplified signal and demodulating the amplified signal at the clock frequency to produce an output signal;
• an input capacitor that couples the modulated signal to an input of the amplifying means;
• means for modulating an amplitude of the output signal at the clock frequency to produce a modulated output signal;
• and
• means for applying the modulated output signal as a feedback signal to the modulated input signal at a node between the input capacitor and an input of the amplifying means via a feedback capacitor.

A method comprising:

• modulating an amplitude of an input signal at a clock frequency to produce a modulated signal;
• amplifying the modulated signal in a mixer amplifier to produce an amplified signal, wherein an input capacitor couples the modulated signal to an input of the mixer amplifier;
• demodulating the amplified signal in the mixer amplifier at the clock frequency to produce an output signal;
• modulating an amplitude of the output signal at the clock frequency to produce a modulated output signal;
• and
• applying the modulated output signal as a feedback signal to the modulated signal via a first feedback path at a node between the input capacitor and the input of the mixer amplifier via a feedback capacitor.

A chopper-stabilized instrumentation amplifier comprising:

• a first modulator that modulates an amplitude of an input signal at a clock frequency to produce a modulated signal;
• a mixer amplifier that amplifies the modulated signal to produce an amplified signal and demodulates the amplified signal at the clock frequency to produce an output signal;
• a second modulator that modulates an amplitude of the output signal at the clock frequency;
• a first feedback path that applies the modulated output signal as a feedback signal to the modulated input signal;
• an integrator that integrates the output signal;
• a third modulator that modulates the integrated output signal at the clock frequency to produce a second feedback signal;
• and
• a second feedback path that applies the second feedback signal to the modulated input signal.

A chopper-stabilized instrumentation amplifier comprising:

• a first modulator that modulates an amplitude of an input signal at a clock frequency to produce a modulated signal;
• a mixer amplifier that amplifies the modulated signal to produce an amplified signal and demodulates the amplified signal at the clock frequency to produce an output signal;
• a second modulator that modulates an amplitude of the output signal at the clock frequency;
• and
• a first feedback path that applies the modulated output signal as a feedback signal to the modulated input signal;
• a second feedback path that applies the output signal to the input signal via a switched capacitor.

A method comprising:

• modulating an amplitude of a input signal at a clock frequency to produce a modulated signal;
• amplifying the modulated signal in a mixer amplifier to produce an amplified signal;
• demodulating the amplified signal in the mixer amplifier at the clock frequency to produce an output signal;
• modulating an amplitude of the output signal at the clock frequency;
• applying the modulated output signal as a feedback signal to the modulated input signal via a first feedback path;
• integrating the output signal;
• modulating the integrated output signal at the clock frequency to produce a second feedback signal;
• and
• applying the second feedback signal to the modulated input signal via a second feedback path.

A method comprising:

• modulating an amplitude of a input signal at a clock frequency to produce a modulated signal;
• amplifying the modulated signal in a mixer amplifier to produce an amplified signal;
• demodulating the amplified signal in the mixer amplifier at the clock frequency to produce an output signal;
• modulating an amplitude of the output signal at the clock frequency;
• applying the modulated output signal as a feedback signal to the modulated input signal via a first feedback path;
• and
• applying the output signal to the input signal via a switched capacitor.

A chopper-stabilized instrumentation amplifier comprising:

• a first modulator that modulates an amplitude of a differential input signal to produce a modulated signal;
• a differential mixer amplifier that amplifies the modulated signal to produce an amplified signal and demodulates the amplified signal at the clock frequency to produce an output signal;
• a first input capacitor coupled between a first output of the first modulator and a first input of the mixer amplifier;
• a second input capacitor coupled between a second output of the first modulator and a second input of the mixer amplifier;
• a first feedback branch comprising a first modulator that modulates the output signal to produce a first modulated output signal, wherein the first feedback branch couples the first modulated output signal to a first node between the first input capacitor and the first input of the mixer amplifier via a first feedback capacitor;
• and
• a second feedback branch comprising a second modulator that modulates the output signal to produce a second modulated output signal out of phase with the first modulated output signal, wherein the second feedback branch couples the second modulated output signal to a second node between the second input capacitor and the second input of the mixer amplifier via a second feedback capacitor.