| 摘要 |
PURPOSE:To eliminate the effect of an offset error by designing the positive of negative converting characteristic in a way that the characteristic is inverted by a digital signal. CONSTITUTION:The level '1' of the MSB is detected by a conversion characteristic inversion detector 1 for a 4-bit digital signal E whose 1st bit it the MSB and whose 4th bit is the LSB, and when the MSB is logical '1', the characteristic is inverted at a point Y as shown in M in figure by a digital signal inverting circuit 2, and the signal M and a negative signal part of a bipolar signal L where the signal zero point of the signal E is taken as the point Y are added by an adder 3 and the result is inputted to a D/A converter 4. The M signal part of the PAM signal processed analogically is inverted by an analog signal inverting device 5. The D/A conversion is delayed by a signal F' inputted to the device 5 from the detector 1. An output signal J of the inverting device 5 and an output signal I of the converter 4 are added by an adder 6 to obtain an output signal K. The inverted point may be taken as a point X and may be inverted at an optional point.
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