Active filtering method and apparatus
US5619166A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 2, 1994 |
| Grant date | Apr 8, 1997 |
| Priority date | — |
| Expiry date | Dec 2, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05F3/245
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An adaptive active filtering method and apparatus that detects changes in noise conditions and reduces the signal propagation speed as noise conditions worsen. This active filter has a level shifting inverter, which inverts the input signal and converts the logic levels of the input signal into chip logic levels. This inverted input signal is presented at the input of a driver inverter, which once again inverts the signal. This second inversion filters out input noise, because a voltage controlled device (which is attached to the driver inverter) reduces the switching speed of this inverter as the noise condition worsen; this reduction in switching speed reduces the propagation speed and thus filters out noise. In addition, two cascaded voltage generator circuits create a reference voltage generator, that enables the voltage controlled device to detect changes in noise conditions, by providing it with a reference voltage that varies in a controlled and specific manner with the changes in transistor conductance parameters, power supply voltages, and operating temperatures. This reference voltage generator controls the variance of the reference voltage in two manners. First, this gen…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.