Demodulator circuit and method of tuning
US6369647B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 21, 2000 |
| Grant date | Apr 9, 2002 |
| Priority date | — |
| Expiry date | Dec 21, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/099
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A demodulator circuit (10) includes an oscillator (12) and an injection circuit (14). An Automatic Frequency Control (AFC) signal adjusts the tail current of a current source (28) provided in the oscillator (12) and the tail current of a current source (44) provided in the injection circuit (14). A phase detector (16) compares the phase of the signal generated by the oscillator (12) with the phase of the injected input signal. The phase detector (16) generates an output signal V0 having a value of zero when the input signal is in quadrature with the signal generated by the oscillator (12), but generates a non-zero signal that is used to adjust the AFC signal when the input signal and the signal generated by the oscillator (12) are not in quadrature.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.