Delta-sigma modulator with limiter

摘要

The stability of a delta-sigma modulator may be improved by limiting a value within the delta-sigma modulator. For example, the value provided to a quantizer may be limited, by a limiter circuit in the delta-sigma modulator, to a value within a single step range of the quantizer. The limiter circuit may be placed in an inner loop of the delta-sigma modulator to decouple the stability of the inner loop from an outer loop. For example, a delta-sigma modulator may be constructed with an inner loop having a sixth order and an outer loop having a second order, in which the stability of the delta-sigma modulator is proportional to that of a second order.

主权项

1. An apparatus, comprising:
a first loop of a delta-sigma modulator; a second loop of the delta-sigma modulator; and a first limiter configured to separate a set of stability characteristics of the first loop of the delta-sigma modulator from another set of stability characteristics of the second loop of the delta-sigma modulator; wherein the first loop of the delta-sigma modulator has an order higher than a second order and the second loop of the delta-sigma modulator is a second-order loop; wherein the first limiter is integrated into the first loop of the delta-sigma modulator; and wherein the first loop implements a noise transfer function having zeroes.