| 摘要 |
PURPOSE:To simplify circuit constitution and eliminate rounding, and to reduce phase delay by impressing a modulated wave to the power terminal of an amplifying circuit, impressing pulse for modulation to the input side of the amplifying circuit, and leading a wave to be modulated out of the amplifying circuit through its output terminal. CONSTITUTION:When pulses for modulation are at 'high', a modulating wave is applied to the input terminal Ti of a CMOSIC 2 through a resistance R1 and the input to the CMOSIC 2 enter a 'high' state because the modulating wave exceeds a threshold voltage. The input signal is therefore inverted and the output of the CMOSIC 2, i.e. the wave to be modulated goes down to 'low'. When the pulses for modulation are at 'low', on the other hand, a diode D1 turns on, the input to the CMOS IC2 goes down 'low', and the output goes up to 'high'. In this case, the input to the CMOSIC 2 generates an output almost as high as a source voltage because the input is at 'low' and the source voltage is the modulating wave which is an analog video signal at a pulse amplitude modulating circuit 1, so the output of the CMOSIC 2 is almost equal in level to the modulating wave eventually. |
