Wideband analog quadrature modulator/demodulator with pre-compensation/post-compensation correction
US6940916B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 26, 2001 |
| Grant date | Sep 6, 2005 |
| Priority date | — |
| Expiry date | Jul 29, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0024
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
The present invention is related to methods and apparatus that compensate for quadrature impairments of an analog quadrature modulator and/or demodulator over a relatively wide signal bandwidth. One embodiment pre-distorts baseband signals in a quadrature modulator compensation signal processor (QMCSP) to negate the quadrature impairment of an analog quadrature modulator and corrects a received baseband signal in a quadrature demodulator compensation signal processor (QDCSP) to cancel the quadrature impairment of an analog quadrature demodulator. The QMCSP and the QDCSP contain adaptive digital filter correction structures that pre-compensate and post-compensate, respectively, for the quadrature impairments introduced by the analog quadrature modulator and the analog quadrature demodulator over a relatively wide bandwidth. A phase shifter advantageously shifts the phase of a local oscillator signal to the analog quadrature demodulator to distinguish quadrature impairments introduced by the modulation path from quadrature impairments introduced by the demodulation path.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.