Charge pump circuit
US5239455A · kind A · utility
12Cited by
2References
6Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Oct 17, 1991 |
| Grant date | Aug 24, 1993 |
| Priority date | — |
| Expiry date | Oct 17, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/0896
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A charge pump circuit for a frequency/phase comparator in a phase locked loop oscillator arrangement, in which current sources utilizing only npn transistors provide currents of equal magnitude but of opposite sense to an input of an operational amplifier, the output of this amplifier charge-pumping a capacitor to control the frequency of oscillation of an oscillator. The use of npn transistors enables higher current levels and higher speed switching compared to circuits including pnp transistors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.