HIGH-ORDER MULTIPATH OPERATIONAL AMPLIFIER WITH DYNAMIC OFFSET REDUCTION, CONTROLLED SATURATION CURRENT LIMITING, AND CURRENT FEEDBACK FOR ENHANCED CONDITIONAL STABILITY

摘要

An amplifier is disclosed including at least three integrator stages connected to provide a low-frequency path from a signal input to a signal output, and a relatively high-frequency bypass path around the first integrator stage. The first integrator stage uses dynamic offset reduction such as chopper stabilization, and an analog low-pass filter reduces artifacts of the dynamic offset reduction. The paths converge at a current summing node. To prevent instability when the integrators are saturated by large signals, the paths have respective saturation current limits selected so that the relatively high-frequency path is not saturated when the low-frequency path saturates. To ensure that the conditional stability is substantially unaffected by adjustment of closed- loop gain, a current feedback input adjusts the open-loop gain in a fashion inversely proportional to resistance presented to the current feedback input by a feedback circuit.