Amplifier

Abstract

Abstract PURPOSE:To automatically compensate the change in the attenuation of input side coaxial cable due to temperature change, by automatically controlling the gain and amount of negative feedback of amplifier with the control signal obtained from the output of amplifier. CONSTITUTION:When TV signal and pilot signal are inputted to the preamplifier 10, they are amplified at the amplifier 12 and the main amplifier 74. The pilot signal detection circuit 84 detects the pilot signal and the control voltage production circuit 88 inputs this signal and inputs the control voltage to the terminals 60, 80. This control voltage flows the currents i1, i2 respectively to the automatic variable resistance circuit 63 in series with the negative feedback circuit 44 and the automatic gain control circuit 83 to adjust the feedback amount and gain so that a given frequency characteristic can be obtained. Accordingly, when the temperature varies and the attenuation of the input side coaxial cable is changed, the gain and amount of feedback are changed accordingly to keep constant the output level of the main amplifier 74.

Inventors

• 👤 Keizo Suehiro

Bibliographic Details