Chopper-stabilized instrumentation amplifier
First Claim
1. 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 an amplitude of 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 the input of the mixer amplifier via a feedback capacitor.
1 Assignment
0 Petitions
Accused Products
Abstract
This disclosure describes a chopper stabilized instrumentation amplifier. The amplifier is configured to achieve stable measurements at low frequency with very low power consumption. The instrumentation amplifier uses a differential architecture and a mixer amplifier to substantially eliminate noise and offset from an output signal produced by the amplifier. Dynamic limitations, i.e., glitching, that result from chopper stabilization at low power are substantially eliminated through a combination of chopping at low impedance nodes within the mixer amplifier and feedback. The signal path of the amplifier operates as a continuous time system, providing minimal aliasing of noise or external signals entering the signal pathway at the chop frequency or its harmonics. The amplifier can be used in a low power system, such as an implantable medical device, to provide a stable, low-noise output signal.
227 Citations
54 Claims
-
1. 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 an amplitude of 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 the input of the mixer amplifier via a feedback capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 49)
-
-
12. 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. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 50)
-
-
27. 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. - View Dependent Claims (51)
-
-
28. 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. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 52)
-
-
39. 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. - View Dependent Claims (40)
-
-
41. 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. - View Dependent Claims (42, 43)
-
-
44. 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. - View Dependent Claims (45)
-
-
46. 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. - View Dependent Claims (47, 48)
-
-
53. 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. - View Dependent Claims (54)
-
Specification