| 摘要 |
PURPOSE: To attain an operation with a small volume and a low power supply voltage by constituting an input circuit of the serially connected circuit of first and second selection amplifier circuits having the maximum gain coefficient in a frequency equal to a clock pulse frequency, and constituting a demodulating circuit of a mean value detector. CONSTITUTION: A photodiode 1 receives an infrared ray, and supplies currents I0 through an input terminal 2.00 to a first selection amplifier circuit 2. The amplifier circuit 2 outputs currents I2.01 from an output terminal 2.01, and the currents are converted into currents the inverse of the I2.01 by a polarity inverting stage 3 and supplied from an input terminal 4.01 to a second selection amplifier circuit 4. The amplifier circuit 4 outputs a signal indicating the rough reproduced wave of a pulse column B, and supplies it to a mean value detector 5. This mean value detector outputs an original message, that is, the rough reproduced wave of a pulse column A. Thus, the first and second selection amplifier circuits are turned into an integrated circuit, a small volume is realized, and any high supply voltage is be unnecessitated. |
