Chopper-stabilized analog-to-digital converter

An implantable medical device comprising:

• a physiological sensor that generates an input signal indicative of a physiological condition;
• and
• a chopper-stabilized analog-to-digital converter (ADC) comprising:
• a first modulator that modulates an amplitude of the input signal at a frequency to produce a modulated input signal;
• a mixer amplifier that amplifies the modulated input signal to produce an amplified signal, demodulates the amplified signal at the frequency to produce a demodulated signal, and integrates the demodulated signal to produce an output signal;
• circuitry that converts the output signal into a digital value that approximates the analog input signal;
• circuitry that converts the digital value into reconstructed analog output signal;
• a second modulator that modulates an amplitude of the reconstructed analog output signal at the frequency to produce a modulated output signal;
• and
• a feedback path that applies the modulated output signal as a feedback signal to the modulated input signal.

A chopper-stabilized analog-to-digital (ADC) converter comprising:

• means for modulating an amplitude of an analog input signal at a frequency to produce a modulated input signal;
• means for amplifying the modulated input signal to produce an amplified signal, demodulating the amplified signal at the frequency to produce a demodulated signal, and integrating the demodulated signal to produce an output signal;
• means for converting the output signal into a digital value that approximates the analog input signal;
• means for converting the digital value into a reconstructed analog output signal;
• means for modulating an amplitude of the reconstructed analog output signal at the frequency to produce a modulated output signal;
• and
• means for applying the modulated output signal as a feedback signal to the modulated input signal.

A method comprising:

• modulating an amplitude of an analog input signal at a frequency to produce a modulated input signal;
• amplifying the modulated input signal to produce an amplified signal;
• demodulating the amplified signal at the frequency to produce a demodulated signal;
• integrating the demodulated signal to produce an output signal;
• converting the output signal into a digital value that approximates the analog input signal;
• converting the digital value into a reconstructed analog output signal;
• modulating an amplitude of the reconstructed analog output signal at the frequency to produce a modulated output signal;
• and
• applying the modulated output signal as a feedback signal to the modulated input signal via a first feedback path.

An analog-to-digital converter (ADC) comprising:

• a first modulator configured to modulate an amplitude of an input signal at a selected frequency to produce a modulated input signal;
• an amplifier configured to amplify the modulated input signal to produce an amplified signal;
• a demodulator configured to demodulate an amplitude of the amplified signal at the selected frequency to produce a demodulated signal;
• an integrator configured to integrate the demodulated signal to produce an output signal;
• circuitry that converts the output signal into a digital value that approximates the analog input signal;
• circuitry that converts the digital value into a reconstructed analog output signal;
• a second modulator that modulates an amplitude of the reconstructed analog output signal at the selected frequency to produce a modulated output signal;
• and
• a feedback path that applies the modulated output signal as a feedback signal to the modulated input signal.

An implantable medical device comprising:

• a physiological sensor that generates an input signal indicative of a physiological condition;
• and
• an analog-to-digital converter (ADC) comprising:
• a first modulator configured to modulate an amplitude of an input signal at a selected frequency to produce a modulated input signal,
• an amplifier configured to amplify the modulated input signal to produce an amplified signal,
• a demodulator configured to demodulate an amplitude of the amplified signal at the selected frequency to produce a demodulated signal,
• an integrator configured to integrate the demodulated signal to produce an output signal,
• circuitry that converts the output signal into a digital value that approximates the analog input signal,
• circuitry that converts the digital value into a reconstructed analog output signal,
• a second modulator that modulates an amplitude of the reconstructed analog output signal at the selected frequency to produce a modulated output signal, and
• a feedback path that applies the modulated output signal as a feedback signal to the modulated input signal.