Schmitt trigger circuit
US4490627A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 17, 1982 |
| Grant date | Dec 25, 1984 |
| Priority date | — |
| Expiry date | Nov 17, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K3/3565
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A Schmitt trigger uses a switched high gain MOS transistor coupled to a control node for speed but a low gain transistor to establish a control voltage on the control node to minimize current flow. In one mode the high gain transistor is switched off to allow the control node to increase in voltage. The low gain transistor limits the voltage on the control node by drawing current therefrom. Such current drawing is delayed in time to avoid reducing the initial rate of increase in voltage on the control node. By limiting the voltage on the control node, the charge stored is reduced thereby reducing effective input capacitance. Additionally, speed is increased when the high gain transistor is turned on because the voltage on the control node does not have to be reduced as far.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.