| 摘要 |
PURPOSE:To set the gain with a simple resistance ratio by generating a digital signal in response to an output of a differential amplifier, feeding back it to the differential amplifier via a D/A converter and changing its output so as to be zero. CONSTITUTION:When an input voltage ei and an analog output of a D/A converter are the same in polarity, the input voltage ei and an output Ea of the D/A converter are cancelled at the differential amplifier. When an output E0 of the differential amplifier is positive, a counter CUT counts up and when negative, the CUT counts down, and when the output E0 becomes zero, the relation of ei and R becomes ei/R=Ea-ei/r and an analog output is a multiple of 1+(r+R) to the input voltage ei. In transmitting the digital signal in this case as the conversion output Ea, a digital signal representing the input voltage ei amplified by the gain of 1+(r/R) is obtained. |
