Time-share I-Q Mixer system with distribution switch feeding in-phase and quadrature polarity inverters
US5974306A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 8, 1997 |
| Grant date | Oct 26, 1999 |
| Priority date | — |
| Expiry date | Aug 8, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03D2200/0082
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An image-rejecting receiver comprises a tunable mixer stage, a time-share I-Q mixer stage, a complex filter, and an image rejector. The time-share I-Q mixer stage includes a switch assembly, inphase and quadrature polarity inverters, and a clock generator. The switch assembly generates pulses and distributes them in alternation to the polarity inverters. Performing distribution prior to polarity inversion preserves the orthogonality of the inphase and quadrature target signal components despite pulse-to-pulse bleeding. Charge accumulated at the distributor switch input is dumped between pulses to further minimize such bleeding. A current-mode field-effect-transistor implementation ensures unity gain across each polarity inverter so that they are gain-matched. Gain matching and preservation of orthogonality optimize the conditions for the complex filter to attenuate and for the image rejector to cancel an image signal. The polarity inverters are switched in quadrature to relax polarity-inverter transition timing tolerances, decreasing costs and increasing reliability.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.