Multistage voltage converter for voltage controlled oscillator
US5821824A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 25, 1997 |
| Grant date | Oct 13, 1998 |
| Priority date | — |
| Expiry date | Aug 25, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2203/45658
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A multistage voltage-to-current ("VI") converter for producing, in response to an input voltage, an output voltage useful for controlling a voltage-controlled oscillator ("VCO"). Preferably, the transfer function of the VI converter is such that the output clock frequency-to-input voltage transfer function (of a system including the VI converter and the VCO) is at least approximately linear over a desired output clock frequency range and has a desired slope in such range. In preferred embodiments, the multistage VI converter includes three differential amplifier stages connected in parallel. Each stage has a tail current and receives a reference voltage (the tail currents and reference voltages typically differ from stage to stage), and produces a component of a total current. The total current determines the output voltage. Optionally, bias circuitry is provided for producing nonzero output voltage in response to zero input voltage. In other embodiments, the multistage VI converter includes two stages or more than three stages connected in parallel, each stage producing a component of a total current which determines the output voltage. The number of stages, and the tail current a…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.