Frequency tuning range extension and modulation resolution enhancement of a digitally controlled oscillator
US7439817B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 29, 2006 |
| Grant date | Oct 21, 2008 |
| Priority date | — |
| Expiry date | Feb 15, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L2207/50
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A novel apparatus and method of extending the frequency tuning range and improving the modulation resolution of an RF digitally controlled oscillator (DCO). In addition to the coarse PVT MIM varactor bank, the DCO uses a single unified bank of varactors that is further subdivided divided into an MSB bank, LSB bank and sigma-delta (SD-LSB) bank. Any ratio mismatches between MSBs and LSBs are digitally calibrated out using a DCO step-size pre-distortion scheme wherein the LSB steps are adjusted to account for the ratio mismatch between the MSB/LSB step sizes. A harmonic characterization technique is used to estimate the mismatches in the minimal size CMOS tuning varactors of a digitally controlled RF oscillator (DCO), wherein the nominal ratio mismatch between the MSB and LSB devices is estimated using hybrid stochastic gradient DCO gain estimation algorithms. The nominal ratio mismatch and the mismatches in the MSB and LSB banks are used to determine the average MSB/LSB mismatch. The average mismatch value is then used to correct the LSB steps.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.