Phase-locked loop having frequency and phase control current pumps
US5319320A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 28, 1993 |
| Grant date | Jun 7, 1994 |
| Priority date | — |
| Expiry date | May 28, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L2207/04
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The frequency control and phase control of a voltage-controlled oscillator (50) of a phase-locked loop (100) comprise two current paths. The frequency control system comprises a filter (75) that converts pulse output current (i.sub.1) of a charge pump (70) generated by phase error signals (X.sub.1, X.sub.2) to a DC voltage, and a resistor (R.sub.1 or R.sub.2) that converts that voltage to DC current (i.sub.3), and the phase control system comprises a charge pump (80) that generates a pulse output current (i.sub.2) using the phase error signals (X.sub.1, X.sub.2). The frequency and phase of the oscillator output (V.sub.OUT) of the voltage-controlled oscillator (50) is controlled by a composite current i.sub.4, which is the sum of the DC current (i.sub.3) and the output current i.sub.2. Since it is possible to make the natural angular frequency proportional to the data transfer rate while the damping factor remains unchanged, by changing the value of the currents (i.sub.3, i.sub.2) through the switching of switches (SW.sub.1, SW.sub.2) when the data transfer rate of the input signal (S.sub.IN) changes, a phase-locking characteristic can be realized that accommodates a wide range of d…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.