Mirror and bias circuit for class AB output stage with large swing and output drive
US5442320A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 9, 1994 |
| Grant date | Aug 15, 1995 |
| Priority date | — |
| Expiry date | Jun 9, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2203/45696
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A complementary transistor class AB output stage (200) utilizes a complementary pair of output drivers (220, 222) connected in series between the power supply rails (210, 216) to furnish the stage output. An output driver (206) is a composite pair of transistors in a Darlington configuration, which boosts the current gain and input resistance of the output stage. Bases of the output drivers are connected by a complementary pair of parallel connected drivers (226, 228), which function as common base level shifters. Quiescent bias of the output drivers is achieved by a pair of constant current transistors (232, 238) that are operated as complementary current mirrors. Inputs to the mirrors are relatively low current sink (252) and source (250) supplies. A level shifter and its corresponding current mirror are configured so that base currents flowing therein, which may be variable due to temperature and process variations, are generally shunted away from the current mirrors and toward an output driver to maintain mirrored currents and assist output drive.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.