The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 04, 2000
Filed:
Mar. 13, 1998
Hsueh-Wu Kao, Hsinchu Hsien, TW;
Industrial Technology Research Institute, Hsinchu, TW;
Abstract
A pseudo two-step current-mode analog-to-digital converter is disclosed, which carries out fine comparison in current mode such that the analog-to-digital conversion can be executed correctly even when the input signal is very small, and thus conserves chip area for implementing the series-connecting resistors. The analog-to-digital converter according to the present invention comprises: a reference voltage generator disposed between a first voltage (V1) and a second voltage (V2) to provide a plurality of reference voltage nodes; a first comparing device for comparing the analog input voltage with the 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 the rough codes; a current conversion device for converting the analog input voltage and the voltage level corresponding to the 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 the fine reference currents to output a set of fine codes, wherein the differential current is the difference between the 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 the rough codes; and a output encoder receiving the significant bit codes and the least bit codes and outputting a set of digital codes after error correcting the significant bit codes.