This paper considers the problem of setting small and accurate delay of those analog quadrature signals generated in the sin/cos encoders within the range of ±10°. Such precision is needed for the efficient phase shift compensation. A typical analog delay circuit is comprised of a summing amplifier and digitally controlled variable resistor used to set a delay of the cos signal. The main disadvantage of this delay circuit is poor linearity. We propose a new circuit based on a voltage divider with about three times better linearity and a completely symmetrical range. The effects of the component tolerances and signals' irregularities on the accuracy of the delay are explored. The detailed theoretical worst case analysis and simulation shows that for the integrated version with the 128-tap digital potentiometer ( R/R = 1 LSB = 0.8%), the tolerances contribute 0.34°to the total error and typical signal irregularities of ∼0.40°. The measurement of the prototype circuit shows that with the discrete elements it is possible to obtain a total error of below 0.2°within the range from 0°to 5°, if the signals are of good quality.Index Terms-Analog quadrature signals, delay circuit, error analysis, phase delay, quadrature encoder signals.

This paper presents a precise macromodel of a signal-phase meter, which allows continuous phase measurement during simulation. It has been developed as a support tool during the design process of a signal-conditioning circuit for incremental position encoders. The development of a signal conditioning circuit requires precise measurements of small signal phases, amplitudes and offsets using the analog/digital circuit simulator. The phase measurement cannot be performed directly with a simulator, therefore an appropriate macro-model is needed for a circuit simulator. The structure of the signal-phase meter is based on the conventional signal-phase measuring method and is intended for the measuring of a cosine-signal phase with a known frequency. It recommends that the time variations of an input signal's parameters (amplitude, phase, frequency, and offset voltage) are slow and small as possible. Rapid change of a signal's parameters decreases the simulation result's accuracy. A macro-model's precision mainly depends on the chosen parameters for the macro-model and for the simulation. We show that with the proposed meter's model, the phase angle can be measured with an accuracy of more than ±0,02%.

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