Fast recovering charge pump for controlling a VCO in a low power clocking circuit
US5523724A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 19, 1994 |
| Grant date | Jun 4, 1996 |
| Priority date | — |
| Expiry date | Aug 19, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L2207/08
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A low power clocking circuit includes a crystal oscillator for generating a digital signal having a first frequency. The first frequency is relatively slow which allows the crystal oscillator to consume reduced power. The phase detector signal is coupled to control a charge pump circuit that generates a voltage on an output node for controlling a voltage controlled oscillator. The VCO generates a clock signal having a second frequency that is higher than the first frequency. The charge pump circuit includes an active mode and a power down mode and is operatively coupled between a first supply voltage and a second supply voltage. As typically provided, the charge pump includes a capacitor network coupled to the output node for maintaining the output voltage. The charge pump includes a voltage control circuit having an up input for increasing the output voltage and a down input for decreasing the output voltage. In addition, a ring enable input is provided for open circuiting all electrical paths from the first supply voltage to the second supply voltage and a precharge circuit is provided for maintaining the output voltage at a predetermined precharge level during the power down mod…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.