| 摘要 |
PCT No. PCT/GB82/00321 Sec. 371 Date Jul. 11, 1983 Sec. 102(e) Date Jul. 11, 1983 PCT Filed Nov. 10, 1982 PCT Pub. No. WO83/01714 PCT Pub. Date May 11, 1983.An amplifier which is particularly suitable for low supply voltage operation and which is relatively insensitive to power supply voltage variations includes a signal amplifying stage (11) and a control stage (10). The signal amplifying stage (11) includes the output load (13), such as a loudspeaker, in series with a transistor (12) which is controlled by a current mirror circuit (14, 15, 16) in the control stage. The circuit acts by continuously comparing part of the voltage across the output load (13) with a very low reference voltage arising from the difference in the base-emitter voltages of two transistors (14, 15) operating at unequal collector current values. This causes voltage excursion peaks appearing at the junction of the output load (13) and the amplifying transistor (12) to be clamped to a voltage equal to or otherwise related to that at the opposite side of the output load (13). |
