Patent ID: 6011502
Filing Date: 2000-01-04
Classification: H03M

Abstract:
A pseudo two-step current-mode analog-to-digital converter for converting an analog input voltage to digital output codes comprising:a reference voltage generator disposed between a first voltage (V1) and a second voltage (V2) to provide a plurality of reference voltages;a first comparing device for comparing said analog input voltage with said reference voltages to output a set of rough codes;a first logic device selectively outputting corresponding bit codes as the output of the significant (higher) bits in accordance with said rough codes;a current conversion device for converting said analog input voltage and the voltage level corresponding to said significant bit codes to an analog input current and a significant-bit reference current respectively, and generating a plurality of fine reference currents;a second comparing device for comparing a differential current with said fine reference currents to output a set of fine codes, wherein said differential current is the difference between said analog input current and significant-bit reference current;a second logic device selectively outputting corresponding bit codes as the output of the least (lower) bits in accordance with said rough codes; andan output encoder receiving said significant bit codes and said least bit codes and outputting a set of digital codes after error correcting said significant bit codes.