| 摘要 |
<p>PURPOSE:To obtain a direct current feeding resistance and an alternating current terminal impedance at the same time by applying a direct current positive feedback, which an operational processing is given to, and an alternating current positive feedback, which the operational processing is given to, upon one pair of reference resistances. CONSTITUTION:A differential amplifying part 51' has the gain of 1/m, and its output is impressed to a direct current operating part 53'. A resistor is connected to the inverted input side of the operating part 53', and the gain m(K-1)/2K is obtained. Besides, the bias voltage source 69 of VBB/m is connected to a not inverted input, and the action of an adder 66 is performed as well. From the output of the operating part 53', a direct current signal component alone is taken out through an LPF, and it is impressed to the first input I of a synthetic feedback part 63, and besides, an alternating current signal component voltage passing through an HPF is impressed to the second input II. Further, the output of a transmitting sound signal source 27 is impressed to the third input III, and a resultant output is transmitted to a feedback routes 64 and 65. A direct current and an alternating current feedback voltages, which have been separately operated, are synthesized, and are fed back to the reference resistances 11, 21 through the amplifiers 61, 62 of the gain 1 respectively.</p> |
