Patent ID: 8736473
Filing Date: 2014-05-27
Classification: H03M

Abstract:
1. A sigma-delta modulator comprising: a plurality of analog filters arranged to generate an integrated differential signal from a combination of an analog input signal and a feedback signal, wherein the analog filters are integrators connected to two output lines and output signals from the two output lines represent a positive variant and a negative variant of the integrated differential signal; a quantizer coupled to the analog filters, the quantizer arranged to generate a quantized signal from the integrated differential signal; a digital integrator coupled to the quantizer for generating a digital signal from at least the quantized signal; a digital to analog converter coupled to an output of the digital integrator, the digital-to-analog converter arranged to receive the digital signal and generate the feedback signal; an error amplifier arranged to receive the analog input signal and the feedback signal, wherein the feedback signal is subtracted from the analog input signal at the error amplifier, and a differential output signal of the error amplifier is fed into the integrators; a summing stage arranged between the integrators and the quantizer; and a plurality of feed-forward branches connected between the integrators and the summing stage, wherein the integrators are serially connected, wherein each of the integrators comprises an amplifier with a capacitor coupled between differential output lines of the amplifier, and wherein each of the feed-forward branches comprises an feed-forward amplifier that is connected to differential input lines of a respective integrator.