| 摘要 |
<p>1,050,952. Valve and transistor amplifying circuits; amplitude modulation. WESTING- HOUSE ELECTRIC CORPORATION. Jan. 27, 1964 [Feb. 25. 1963]. No. 3355/64. Headings H3R, H3T and H3W. An amplifying system comprises a plurality of signal paths each responsive to the input signal and generating a signal changed in phase with respect to that of the input signal, in which at least one path produces a variable phase shift proportional to the amplitude variations of the input signal. Amplifying means are connected in each of the signal paths, an output circuit receiving an output from each amplifying means and performing a vector summation of all the amplified signals so as to produce an output signal which reproduces the input signal in amplified form. In one embodiment the input signal from terminals 11, 12, Fig. 3, comprising an amplitude modulated carrier, is applied to a limiter 14 which removes the modulation. The resultant unmodulated carrier is fed to an amplifier 22 giving a phase-shift of 180 degrees and also to a phase modulator 20 which produces a phaseshift proportional to the original amplitude modulation. The outputs from phase-modulator 20 and amplifier 22 are fed respectively to amplifiers 28, 30 which may be non-linear. The outputs from amplifiers 28, 30 are combined, either by simple addition in an output load (Fig. 1, not shown) or by means of an untuned network 45 in which transformer 48 is provided with a centre-tapped secondary 49 so as to combine the output from amplifier 28 both in aiding sense and in opposition to that from amplifier 30, fed in via transformer 51: the additive term appears at the output load 36 and the subtractive is absorbed in isolator 40. In another embodiment, the amplitude modulated signal from terminals 11, 12, Fig. 5, is fed to a phase-splitter 21 which produces two outputs on lines 25, 27 the phases of which differ by 90 degrees. These are respectively fed to a linear amplifier 19 and a limiter amplifier 14, the output of the latter being of constant amplitude. The outputs of amplifiers 19, 14 are combined by a transformer 60 in such a manner that the outputs on lines 54, 58, while still amplitude modulated, are of equal amplitude and equally and oppositely phase-modulated in proportion to the amplitude modulation (Fig. 6, not shown). The signals on lines 54, 58 are amplified in amplifiers 28, 30, which may be non-linear, and are recombined in network 45, the summation being fed to aerial 75 and the difference to isolator 40. The arrangement is more particularly intended so as to enable high-efficiency non-linear amplifiers of the type described in Specification 1,037,826, to be used to provide an overall amplification which is linear.</p> |
