Digitally programmable linear phase filter having phase equalization
US5325317A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 12, 1993 |
| Grant date | Jun 28, 1994 |
| Priority date | — |
| Expiry date | Apr 12, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B20/1258
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A digitally programmable Bessel filter includes a plurality of serially connected stages or biquads with each biquad including a plurality of programmable operational transconductance amplifiers. The first stage of the filter provides an all pass equal amplitude response. Two stages provide pulse slimming (first and second derivatives of an input pulse), and three stages provides a sixth order Bessel low pass function. The operational transconductance amplifiers are controlled by a fine tuning control signal, and an array of integrating capacitors are selectively controlled by a coarse tuning signal. The fine tuning and coarse tuning signals are generated in a phase locked loop from a reference clock and a reference biquad which receives the reference clock. The phase locked loop includes a phase detector responsive to the reference clock and the reference biquad, whose output is integrated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.