Comparator with hysteresis for interfacing with a ground-referenced A.C. sensor
US4286176A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 16, 1979 |
| Grant date | Aug 25, 1981 |
| Priority date | — |
| Expiry date | Apr 16, 1999 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF02P7/061
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An interface circuit is disclosed for receiving a ground-referenced A.C. signal for detecting transitions of the A.C. signal about ground potential. An input transistor is enabled when the A.C. signal voltage falls below ground potential by one base-emitter forward drop. The input transistor is disabled when the A.C. signal voltage rises above ground potential by one base-emitter forward drop. A feedback circuit and a bias circuit are coupled to the input transistor for switching the threshold levels of the input transistor. The interface circuit employs a hysteresis-type switching action for improving noise immunity while providing a symmetric output waveform. The circuit requires only a single power supply and is suitable for fabrication as a highly dense, monolithic integrated circuit. Also, the circuit provides a low input impedance to large positive and negative voltage transients.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.