Patent ID: 7796073
Filing Date: 2010-09-14
Classification: H03K,H03M

Abstract:
1. A current switch circuit comprising a current source and a differential switch connected to an output terminal of the current source, wherein the current source includes at least one transistor having a gate terminal to which a bias voltage is applied that determines a value of a current to conduct, the differential switch includes first and second transistors, each of the transistors having source terminals connected to the output terminal of the current source, drain terminals as first and second output terminals respectively, and gate terminals to which complementary signals are inputted, the current switch circuit further comprises a threshold voltage control circuit for outputting a substrate voltage to a substrate terminal of each of the first and second transistors to adjust a threshold voltage of the first and second transistors, the threshold voltage control circuit has a monitoring transistor corresponding to the first and second transistors, and a substrate voltage of the monitoring transistor is provided to both of substrates of the first and second transistors, the substrate voltage of the monitoring transistor being generated so that a threshold voltage of the monitoring transistor has a predetermined value according to a voltage value given from an exterior.