Low-pass filter circuit with variable time constant
US4749951A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 21, 1985 |
| Grant date | Jun 7, 1988 |
| Priority date | — |
| Expiry date | May 21, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H11/12
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A low-pass filter circuit comprises a low-pass filter including a series connection of first and second resistors and having one end connected to an input terminal and a capacitor connected between the other end of the series connection and the ground, a phase inverting amplifier having an input connected to the other end of the series connection, a feed back circuit connected between the input and output of the phase inverting amplifier and having a predetermined time constant, and a diode connected in parallel with the first resistor. The diode may be connected, with the cathode connected to the input terminal, so that the electric charge of the feed back circuit may be discharged. Alternatively, the diode may be connected, with the anode connected to the input terminal, so that the electric charge may be charged to the feed back circuit. Alternatively, two diodes may be connected in parallel with the first resistor, with the cathode of one of the diodes connected to the input terminal while with the anode of the other of the diodes connected to the input terminal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.