This disclosure describes a chopper-stabilized sigma-delta
analog-to-digital converter (ADC). The ADC is configured to provide
accurate output at low frequency with relatively low power. The
chopper-stabilized ADC substantially reduces or eliminates noise and
offset from an output signal produced by the mixer amplifier. Dynamic
limitations, i.e., glitching that result from chopper stabilization at
low power are substantially eliminated or reduced through a combination
of chopping at low impedance nodes within the mixer amplifier and
feedback. The signal path of the ADC 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. In this
manner, the chopper-stabilized ADC can be used in a low power system,
such as an implantable medical device (IMD), to provide a stable,
low-noise output signal.