Engineers in the NASA Goddard Space Flight Center Instrument Electronics Development Branch have developed a chopper-stabilized auto-zero amplifier capable of amplifying signals with extremely small amplitude originating from a thermopile-based infrared (IR) sensor. The instrument is self-adjusting in that it corrects for offset shifts caused by total ionizing dose (TID). It is therefore suitable for use in environments with high TID and large fluctuations in TID, such as those found in the Jupiter system. This technology allows for the manufacture of radiation-hardened amplifiers with low offset and noise.
This innovation reduces the offset of a differential amplifier in a negative feedback process. In order to accomplish this, a latched window comparator network is utilized to monitor the output offset of a differential amplifier. An integrator receives the signals from the latched window comparator network and subsequently relays an adjustment signal back to the differential amplifier. The auto-zero differential amplifier has proven effective in IR signal processing applications where the signal amplitudes are very small.