Patent ID: 6573851
Filing Date: 2003-06-03
Classification: H03F,H03M

Abstract:
An analog-to-digital converter (ADC) to convert an analog input signal to a N-bit digital output signal, comprising:a reference voltage generator that outputs a plurality of differential reference voltage signals; a pre-amplifier having a plurality of cascaded, differential, switched-capacitor circuits, wherein each of said cascaded, differential, switched-capacitor circuits outputs a difference between one of said plurality of reference voltage signals and a differential analog input signal, such that said pre-amplifying block outputs a plurality of pre-amplified difference signals, wherein each of said cascaded, differential, switched-capacitor circuits has pairs of differentially coupled switched-capacitors, amplifiers, input capacitors, feedback capacitors, and output switch limiting transistors, said switched-capacitors receiving a pair of said plurality of differential reference voltage signals and said differential analog input signal, each of said input capacitors being coupled between a respective one of said switched-capacitors and a respective amplifier, each of said feedback capacitors being coupled across an input and an output of its respective amplifier, each of said amplifiers outputting one of said pre-amplified difference signals, and said output switch limiting transistors being coupled between said outputs of said amplifiers; a comparator that receives said plurality of differential pre-amplified signals and said non-overlapping dual phase clock signal, and assigns one of a binary 1 and a binary 0 to each of said pre-amplified outputs and outputs said binary 1's and 0's to an encoder; wherein said encoder receives said binary 1's and binary 0's and said non-overlapping dual phase clock signal and outputs a binary code; a decoder that receives said binary code and outputs a digital signal; and a clock signal line that feeds a non-overlapping dual phase clock signal into said pre-amplifier, said comparator and said decoder.