Load impedance detector for audio power amplifiers
US4549147A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 31, 1983 |
| Grant date | Oct 22, 1985 |
| Priority date | — |
| Expiry date | Mar 31, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F3/183
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Disclosed is a load impedance detector for detecting a variation of the load impedance of a single-ended push-pull amplifier having a pair of first and second transistors, the emitters of which are interconnected by a pair of series-connected first and second resistors forming a first node to which the load impedance is connected. Third and fourth resistors are connected in series to the emitter of the first transistor to form a bridge circuit with the first resistor and the load impedance so that the third and fourth resistors define a second node therebetween. A voltage difference between the first and second nodes is detected by a differential circuit which is responsive to there being a simultaneous presence of a first state in which the detected voltage difference is higher than a first predetermined value and a second state in which the potential across the load impedance is higher than a second predetermined value for generating an output signal. This output signal is utilized for controlling the level of the voltage supplied to the amplifier to compensate for the impedance variation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.