| 摘要 |
PURPOSE:To correct accurately the integration gains of both the 1st and 2nd integrators and to improve the deterioration in the S/N characteristics at a high input level, by using the 1st - 4th amplifiers, and setting the amplification degree of each amplifier at a specific level, respectively. CONSTITUTION:The 1st and 2nd preamplifiers 14 and 18 which correct the integration gains are provided to the 1st and 2nd integrators 15 and 19, respectively. While the 3rd and 4th amplifiers 22 and 23 for correction are set at the feedback signal input sides of the 1st and 2nd adders 13 and 17, respectively. The analog input signal IS supplied from an input terminal 11 undergoes the prescribed processing through the adder 13, the amplifier 14, the integrator 15, a delay unit 16, the adder 17, the amplifier 18, the integrator 19 and a quantizer 20 respectively. Thus the digital signal OS is outputted through an output terminal 12. Here the amplification degrees of amplifiers 14-23 are set at 0.5, 2.0, 1.0 and 1.0 respectively. Thus it is possible to improve the the S/N characteristics at a high input level compared with a conventional modulation circuit while the advantages of the conventional modulation circuit maintained as they are.
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