Assessment of stability of frequency characteristics of controlled phase shifter

Phase shifters, made on the basis of the phase filters, face strict requirements in respect to the stability of output characteristics. These characteristics primarily consist of transfer ratio and the phase shift between the output and the input vibrations. The paper considers the assessment of stability of the output parameters of the controlled phase shifter based on an all-pass filter of the first order with a system of compensation for the disturbance. The block diagram of the phase shifter with two operational amplifiers, a divider, a converter "period–voltage", a condenser and five resistors is introduced. The analysis of the output characteristics of the phase shifter is made with the use of a computational and analytical method that can be considered the most accurate and efficient, taking into account the parameter spread of radio elements. The paper presents the analytical expressions, linking the main output characteristics of the phase shifter with deviations of the parameters of radioactive elements of the device. The formulas obtained are accurate and allow for calculation of the output characteristics (transfer ratio and phase shift) of the phase shifter under significant deviations of the parameters of radioactive elements from the nominal values. Mathematical expressions for evaluation of the stability of the output characteristics are presented in relative units that make it convenient to use them. The recommendations for optimum adjustment of the phase shifter are given. The phase shifter provides stable phase shifts between the input and output signals in a wide range of frequency and the amplitude of input signal. Studies on the mathematical model in the software package PSIM-9 fully confirmed the received analytical expressions. The phase shifter can be configured in an integrated or hybrid type.