Phase-locked loops having two amplifiers for driving a vco
US5874862A · kind A · utility
2Cited by
11References
8Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Mar 31, 1997 |
| Grant date | Feb 23, 1999 |
| Priority date | — |
| Expiry date | Mar 31, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/40
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A phase-locked loop employing a charge pump 7 for synthesizing RF channels permits a low supply voltage to be used by using two amplifier stages 5a, 5b, between the charge pump and a VCO4. Stage 5a may be a high impedance common emitter pair of complementary transistors allowing a wide voltage swing. Stage 5b may be an operational amplifier with resistive feedback to provide gain less than unity and a low impedance output to provide feedback around a loop filter 6 to source the current from charge pump 7 entering an inverting input of stage 5a. Alternatively, stages 5a, 5b may be reversed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.