| 摘要 |
PURPOSE:To eliminate a phase shift of output and to ensure the image resolution according to the number of bits of the input data, by using a means which changes the amplitude in response to the set of the input data and delivers a signal having the same phase as a reference signal and a phase switching means which delivers the output signal after switching it to the same phase or the opposite phase. CONSTITUTION:The phase of the output of the double quadrant obtained from a D/A converter part 1 and an amplifier 2 are switched by a phase switch 3 and by means of a sign signal. Thus the 4-quadrant output is obtained. When the input data is swept, the sign signal of 0 deg. or 180 deg. is supplied to the switch 3 for input data 1111-0001. thus the signal having the same or opposite phase as or to the output of the amplifier 2 emerges at the output Vout. Then the signal of the opposite or same phase to or as the sign signal of 180 deg. or 0 deg. is supplied to the switch 3 with input data 0000 or the following 0001. Thus only a forward or reverse phase output exists to a reference signal Vref as long as the switch 3 works accurately.
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