Integrated accurate thermal frequency reference
US6121848A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 14, 1999 |
| Grant date | Sep 19, 2000 |
| Priority date | — |
| Expiry date | Jan 14, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L1/02
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A thermal RC network is fabricated in silicon as a lateral array of forward-biased PN junctions, which may take the form of the base-emitter junctions of bipolar transistors. Application of a clock signal from a voltage controlled oscillator to the silicon produces a heat pulse which propagates across the arrayed transistors of the thermal RC network. The resulting change in temperature produces a change in the V.sub.be of the arrayed transistors. The phase shift between the original clock signal and the changed V.sub.be is determined solely by the time constant .tau. of the particular thermal RC network. This time constant is a function only of the intrinsic thermal resistance and thermal capacitance of the silicon and the spacing of the laterally-arrayed transistors. The time constant is independent of the amplitude, frequency, and duty cycle of the original clock signal. The original clock signal and the time-delayed output of the RC network can be compared, and the phase shift determined. A voltage corresponding to this phase shift is then generated and fed back into the voltage controlled oscillator, producing an output signal having a constant frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.