Frequency translating sigma-delta modulator

Abstract

An electronic device for converting an analog input signal into a digital output signal includes: a summing device for adding the analog input signal with a feedback analog signal and for generating a summer output signal representative of the sum of the analog input signal and the feedback analog signal; an analog filter coupled to the summing device for filtering undesired signal components from the summer output signal; an analog mixer receiving a signal having a first mixer frequency and coupled to receive the output of the analog filter for frequency translating the filtered summer output signal to a frequency translated summer output signal having one or more frequency components different than the input frequency; a quantizer coupled to the analog mixer for sampling the frequency translated summer output signal at a sampling frequency and for generating the digital output signal; and a feedback branch coupled between the quantizer and summing device for providing the feedback analog signal to the summing device. The feedback branch includes a digital mixer coupled to the quantizer, the digital mixer having a second mixer frequency for frequency translating the digital output signal to a frequency translated digital output signal; and a digital-to-analog converter for converting the frequency translated digital output signal to the feedback analog signal having a frequency equal to the input frequency. The device utilizes frequency translation inside the feedback loop to perform direct conversion of the analog signal to baseband.

Dependencies are inferred from the claim text.