Patent ID: 7423566
Filing Date: 2008-09-09
Classification: H03M

Abstract:
1. A sigma-delta modulator, comprising: digital feedback signal source for providing a digital feedback signal; a passive discrete time circuit for receiving the digital feedback signal and an input signal, the input signal comprising information and a pair of analog input currents; converting the digital feedback signal into an analog feedback signal during a first discrete time; and summing the analog feedback signal and a selected one of said pair of analog input currents during a second discrete time to yield a summed signal; a passive continuous time circuit comprising a plurality of passive resistive and capacitive elements, the continuous time circuit coupled to the discrete time circuit to filter the summed signal using a first first-order filter containing resistive and capacitive elements serially connected to a second first order filter containing resistive and capacitive elements to form a second first order filter to generate a filtered signal, the first-order filters comprising one or more first passive elements of the plurality of passive elements, and a quantizer coupled to the continuous time circuit to generate the digital signal using the filtered signal, the digital signal comprising the information, said digital signal determining the selected one of said pair of input signals.