Portable radio device with direct conversion receiver including mixer down-converting incoming signal, and demodulator operating on downconverted signal
US6693977B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 16, 2001 |
| Grant date | Feb 17, 2004 |
| Priority date | — |
| Expiry date | Apr 27, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03D3/007
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A direct conversion receiver includes a local oscillator for generating a first local oscillator signal having a variable frequency. A 90° phase shifter operates for shifting a phase of the first local oscillator signal by 90° to convert the first local oscillator signal into a second local oscillator signal. A first mixer operates for mixing a received RF signal and the first local oscillator signal. A second mixer operates for mixing the received RF signal and the second local oscillator signal. A first low pass filter processes an output signal of the first mixer. The first low pass filter has a controllable cutoff frequency. A second low pass filter processes an output signal of the second mixer. The second low pass filter has a controllable cutoff frequency. A demodulator recovers an information signal represented by the received RF signal from output signals of the first and second low pass filters. A frequency error detector operates for detecting an error between a frequency of a carrier of the received RF signal and the frequency of the first local oscillator signal in response to the information signal recovered by the demodulator. An oscillator controller operate…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.