CMOS PECL driver with programmable current for varying voltage swings and termination types
US5874837A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 28, 1997 |
| Grant date | Feb 23, 1999 |
| Priority date | — |
| Expiry date | Apr 28, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K19/018585
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A differential-output current driver is constructed entirely of CMOS transistors. Pseudo-ECL levels are reached when a standard resistive termination is connected to the outputs. The current driver can also drive a non-standard termination to the PECL levels. The non-standard termination is low power because it does not draw standby current from power to ground. Current from the current sources within the current driver are assigned to either the switching current or the constant current. The constant current is applied directly to the outputs to drive the termination to a bias point. The switching current is applied to a differential pair of transistors which switch the switching current to one or the other of the differential outputs in response to a differential input. The constant current is combined with any switching current output from the differential transistors and applied to the differential outputs to drive the external termination. For the non-standard termination, the differential outputs are driven with more constant current and less switching current than for the standard termination. The transconductance of the differential pair of transistors may also be increased…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.