| 摘要 |
<p>METHOD OF AND APPARATUS FOR PRODUCING A LOGARITHMIC REPRESENTATION OF AN INPUT VOLTAGE An input voltage is converted into a logarithmic representation thereof by exponentially changing the charge of a capacitor, producing pulses at a rate dependent upon the time taken for the charge to change between the two reference voltages, and counting the pulses during the time taken for the charge to change between the input voltage and a reference voltage, whereby the conversion is independent of the precise time constant governing the exponential change. The pulses can be produced under the control of a phase-locked loop, or by frequency-dividing clock pulses by a count which has been previously established by frequency-dividing the same clock pulse frequency by a predetermined factor. The conversion can be effected rapidly and accurately for input voltages within a relatively large range, without using high-precision components.</p> |
