Low offset automatic frequency tuning circuits for continuous-time filter
US6400932B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 3, 1999 |
| Grant date | Jun 4, 2002 |
| Priority date | — |
| Expiry date | Dec 3, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/06
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
The present invention relates to a tuning circuit, more specifically to a tuning circuit for continuous-time filter capable of making exact the Gm value to minimize the variation of the cutoff frequency due to the variation of process in the Gm-C type of continuous-time filter. According to the invention, a frequency tuning circuit is provided which comprises integrating means for generating a signal discharging from a first reference voltage to a first predetermined value and a signal charging from a second reference voltage to a second predetermined value; offset sampling means for sampling the offset voltages of the Gm cells by receiving a current multiplied by the offset voltages from the Gm cells included in the integrating means and providing a feedback path between the output nodes and the input nodes of the included Gm cells; comparative signal generating means for generating a comparative signal by generating a reference signal by dividing a clock inputted from the external, receiving the signal discharging from the first reference voltage to the first predetermined value and the signal charging from the second reference voltage to the second predetermined value from the i…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.