Low phase-noise oscillator
US7847650B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 17, 2007 |
| Grant date | Dec 7, 2010 |
| Priority date | — |
| Expiry date | Feb 3, 2028 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03B2200/0074
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A tail-tank coupling technique combines two complementary differential LC-VCOs to form a quadrature LC-VCO. The technique reduces phase noise by providing additional energy storage for noise redistribution and by cancelling noise injected by transistors when they operate in the triode region. The resulting noise factor is close to the theoretical minimum 1+γ, similar to a differential LC-VCO driven by an ideal noiseless current source. However, its figure-of-merit is higher, due to the absence of voltage head-room being consumed by a current source. The optimal ratio of tail-tank capacitor to main-tank capacitor for minimizing phase noise is approximately 0.5. The method can be extended to combine any even number of LC tanks resonating at fo and 2fo to form an integrated oscillator producing quadrature phase at frequency fosc and differential output at 2fosc.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.