| 摘要 |
<p>An analog/digital converter wherein an analog input signal is applied to a variable gain input amplifier which has an output connected to a subtractor. Also connected to the subtractor is the output of a D/A converter, the input of which is connected to the output of an integrator. The subtractor forms from the output signal of the input amplifier and that of the D/A converter a difference signal which is used by a tracking circuit for generating tracking signals for the integrator. For the purpose of widening the dynamic range, the input amplifier contains four scaling amplifiers, one of which is connected by a selection switch to the output of the input amplifier. The scaling factors of the second, third, and fourth scaling amplifiers are 1/4, 1/16, and 1/64, respectively, of that of the first scaling amplifier. If the output of the integrator exceeds predetermined limits, a control logic circuit sets the selection switch to the scaling amplifier having the next-smaller scaling factor, effects a resetting of the output signal of the integrator which corresponds to a division by four of this signal when it exceeds one of the limits of the output range and indicates the respectively valid scaling factor. Switching operations into the other direction take place at zero crossings of the output signal of the integrator. The analog/digital converter is particularly suitable for processing the output signal of a current or voltage converter.</p> |
