Charge pump circuit with symmetrical current output for phase-controlled loop system
US5508660A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 25, 1995 |
| Grant date | Apr 16, 1996 |
| Priority date | — |
| Expiry date | Apr 25, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/0896
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A phase-controlled loop system having a charge pump circuit including a current mismatch measurement circuit and a current compensation circuit for equalizing the amplitude of positive current pulses and the amplitude of negative current pulses output when the phase-controlled loop system is in phase-locked condition. The current mismatch measurement circuit includes duplicate complementary current sources with characteristics and biasing substantially identical to that of the primary current sources providing the positive current and the negative current to the output node of the charge pump circuit. At the common connected node between the duplicate complementary current sources an error current is produced having an amplitude equal to the difference between the amplitude of the positive current pulses and the amplitude of the negative current pulses to the output node. Current mirrors then reflect this error current back to either the positive current source or the negative current source for combining with the positive current or negative current, respectively, such that the currents' amplitudes at the output node substantially cancel. Various current mismatch measurement circu…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.