High frequency lock detecting circuit
US4870382A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 22, 1988 |
| Grant date | Sep 26, 1989 |
| Priority date | — |
| Expiry date | Jul 22, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S331/02
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
The present invention provides a high frequency lock detecting circuit for generating a signal indicative of a locked or a not locked phase tracking condition in a phase locked loop circuit. The lock detector comprises a plurality of high speed function generators two of which are coupled to the modulated data streams for indicating the phase data streams and a third high speed function generator is coupled to the voltage error signal of the phase locked loop for indicating the absence or presence of a voltage error signal. The analog outputs of the function generators are summed together in a summing circuit and applied to a differential amplifier which removes the complex modulated data products from the output of the function generators and provides a signal which is equal to the absolute value of the data signals applied to the first function generators minus the absolute value of the error signal applied by the third function generator. The lock detection signal is applied to the sweep controls of the phase locked loop for controlling the sweep circuits associated with the voltage controlled oscillator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.