Logarithmic converter
US4065682A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 22, 1976 |
| Grant date | Dec 27, 1977 |
| Priority date | — |
| Expiry date | Mar 22, 1996 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06G7/25
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A system for deriving a voltage which is a logarithmic function of peak value of an audio signal, in which the audio input signal is amplified by means of an operational amplifier having bipolar feedbacks through a pair of oppositely poled rectifying junction devices operating over logarithmic portions of their response characteristics, the output of the operational amplifier being applied in opposite polarities to a second pair of rectifying junction devices to rectify a bipolar signal applied thereto, and to control current flow to a storage capacitor, the second pair of devices having a common load which provides a constant current source for slow charge of the storage capacitor in one sense, the second pair of devices providing rapid discharge paths in the opposite sense. In one embodiment either or both pairs of rectifying junction devices can be transistors. Improved operation occurs with transistors in that they exhibit gain as well as rectifying characteristics which increases the range of the inventive circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.