Switched-transconductance multiplexer circuit with integrated T-switches
US5910780A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 13, 1996 |
| Grant date | Jun 8, 1999 |
| Priority date | — |
| Expiry date | Nov 13, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/002
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A switched-transconductance circuit used in a multiplexer forming a part of a crosspoint switch includes integrated T-switches that are enabled when the transconductance stage is not enabled. The transconductance stage is selectively enabled by controlling a split-tail current source driving a differential pair of input transistors. When the transconductance stage is disabled (1) a pair of switches connected between the collectors of the differential pair and a positive voltage supply node are enabled, (2) a pair of cascode transistors connected between the collectors of the differential pair and output leads of the circuit are reversed biased by the positive supply voltage passing through the pair of switches, and (3) a switch is enabled between a common emitter node of the differential pair and a low impedance constant voltage node. In this manner, a pair of common collector T-switches and an emitter T-switch are formed, respectively, between the inputs and output and between the differential inputs of the transconductance stage when the transconductance stage is disabled. When the transconductance stage is enabled, the emitter T-switch is disabled and an additional current sourc…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.