Bipolar differential pair based transconductance element with improved linearity and signal to noise ratio
US5289136A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 28, 1992 |
| Grant date | Feb 22, 1994 |
| Priority date | — |
| Expiry date | Dec 28, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2200/456
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A bipolar differential pair based transconductance element with improved linearity and signal to noise ratio is described. The circuit of the present invention comprises two sets of differential pairs of bipolar transistors in parallel. Each differential pair implements transistor area ratios in the emitter areas. The present invention also comprises diodes that are coupled to the emitters of the transistors of the differential pairs. When the device areas are ratioed properly, the range for the input voltage signal that still allows a linear output current equation increases by a factor of 2 over prior art circuits. The improved linearity, as well as improved signal-to-noise ratio, is achieved by coupling the diodes to the emitters of the transistors and also having the differential pairs in parallel with their transistor areas proportional to each other. An alternative embodiment of the present invention is also described which also uses a level shifting stage. In this embodiment, the required ratios can be set by means of the level shift transistors allowing for the use of all identical core transistors and diodes. Since all the identical core transistors and diodes are minimum …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.