Chopper stabilization in analog multipliers

Abstract

The multiplier is a fundamental analog building block. Analog multipliers are used in many systems such as filters, neural networks, automatic gain control circuits, and phase alignment systems. As with any circuit, analog multipliers are plagued by DC offsets. When considering techniques for removing this offset, the question of continuous regulation versus calibration arises. We can easily implement a calibration method, however, how often one must calibrate becomes an issue. Additionally, calibration typically forces the multiplier to suspend normal operation while the offsets are being measured. In this thesis, a technique for continuously regulating offset in multipliers is studied in isolation. Chopper stabilization, a technique long used in DC amplifiers, is applied to analog multipliers to achieve the lowest offset reported.