| 摘要 |
PURPOSE:To realize an inexpensive and high performance digital modulator- demodulator circuit by using in common a weighting current source for both modulation and demodulation sources, and switching alternately the weighting current source for modulation and demodulation in time division. CONSTITUTION:A clock pulse of a prescribed period is generated from a clock pulse generating circuit 15, and an analog switch 4 and a changeover circuit 13 are turned on when the level of the pulse is at '1' to apply modulation. When the level is at '0', an analog switch 5 and a changeover circuit 12 are turned on to apply demodulation. Since the weighting current source 1 is used in common in case of the modulation and demodulation, no error is caused in the demodulation and no highly accurate component is required for the component of the weighting current source. Thus, the titled circuit is constituted inexpensively and easily of resistors of low accuracy in case of circuit integration.
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