Fuse-trimmed tank circuit for an integrated voltage-controlled oscillator
US6445257B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 4, 2000 |
| Grant date | Sep 3, 2002 |
| Priority date | — |
| Expiry date | Oct 4, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03J2200/36
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A fuse-trimmed tank circuit for an integrated voltage-controlled oscillator (VCO). The tank circuit includes an L-C portion; a cross-coupled pair of transistors, whose collectors are coupled to the L-C portion; a capacitor coupled across the emitters of the cross-coupled pair of transistors; and a pair of resistors, where each resistor is coupled between a corresponding one of the emitters and a ground node. This oscillator circuit provides improved performance over prior oscillator circuits. A technique for trimming the VCO is utilized to adjust its center frequency. Capacitance for the L-C portion of the tank circuit is provided by one or more varactor diodes. When the VCO is operational, the varactors are reverse biased and, thus, act as capacitive elements. One or more of the varactors has an associated fuse coupled in series with the corresponding varactor. To trim the center frequency of the VCO, the capacitance of the L-C portion is adjusted by selectively blowing the fuses. To blow a fuse, a dc voltage is applied to forward bias the corresponding varactor such that the resulting current is sufficiently high to blow the fused. In the preferred embodiment, the varactors are a…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.