| 摘要 |
PCT No. PCT/GB96/01616 Sec. 371 Date May 6, 1997 Sec. 102(e) Date May 6, 1997 PCT Filed Jul. 8, 1996 PCT Pub. No. WO97/04523 PCT Pub. Date Feb. 6, 1997A power control circuit (10) contains a voltage controlled attenuator (16) in combination with a logarithmic converter (24) to produce linear amplification of an input signal (12) over as wide a frequency output range. A logarithmic converter for use in such a power control circuit is provided, including an amplifying circuitry (60) with a non-inverting (66) and inverting (70) input and an output (64), and two feedback circuits (62, 68). The feedback circuits are separably connected between the output and an input of the amplifying circuitry, so that the first feedback circuitry (62) produces a feedback signal which results in the amplifying circuitry (60) exhibiting a non-linear characteristic and the second feedback circuitry (68) contains at least one reactive element (108) to limit the feedback signal from the first feedback circuitry (62) above certain signal levels.
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