MEASUREMENT OF THE AMPLITUDE RATIO AND VOLTAGE PHASE DIFFERENCE WHEN DETERMINING FREQUENCY PARAMETERS OF OPERATIONAL AMPLIFIERS
Background. The authors developed a software-controlled instrument measuring the amplitude ratio and voltage phase difference for determining the unity gain frequency from 0,1 MHz to 10 MHz, and phase stability margin of operational amplifiers. Materials and method. The authors determined the operating range boundaries of measurements of the amplitude ratio and voltage phase difference. For simultaneous transformation of the amplitude ratio and input and output voltage phase difference of operational amplifiers into constant voltages the researchers used a AD8302 detector. Results. The authors developed a test bench and methods for experimental determination of calibration characteristics for an instrument measuring the amplitude ratio and an instrument measuring the signal phase difference. The correlation enables to formulate the resolution requirements for the ADC that digitizes the output voltage ratio of an instrument for measuring the signal amplitude ratio on the basis of a desired frequency resolution when measuring unity gain frequencies of operational amplifiers. Conclusions. The authors experimentally confirmed the possibility of determining the amplitude ratio of signals on the inputs of the detector with a relative error less than 0,15% and the phase difference with a relative error not exceeding 1,5%.