FLASH TYPE ANALOG/DIGITAL CONVERTER

摘要

PURPOSE: A flash type analog/digital converter is provided to reduce the number of comparator and the number of resistance by using the characteristic of a thermometer code. CONSTITUTION: The first channel comparison portion(190) is formed with the first to the eighth comparators(100-114). The second channel comparison portion(192) is formed with the ninth to the sixteenth comparators(140-154). The first reference resistance line(138) is formed by connecting directly the first to the eighth resistances(R1-R8) with each other. The second reference resistance line(136) is formed by connecting directly the ninth to the sixteenth resistances(R9-R16) to each other. The first switch portion(134) is formed with the first to the seventh switches(116-128). The second switch portion(174) is formed with the eighth to the fourteenth switches(156-168). The first code generation portion(180) performs a logical operation for an intermediate code value of the first comparator(100) and half thermometer codes of the second to the eighth comparators(102-114) and outputs the result as a full thermometer code. The second code generation portion(182) performs the logical operation for an intermediate code value of the ninth comparator(140) and half thermometer codes of the tenth to the sixteenth comparators(142-154) and outputs the result as the full thermometer code. The first encoder(184) receives the full thermometer code from the first code generation portion(180) and outputs digital data to an output terminal(OUT1). The second encoder(186) receives the full thermometer code from the second code generation portion(182) and outputs digital data to the output terminal(OUT2).