Measurement Technique Of Mixed-signal System Based On Multitone Stimulus Phase Reference

Nonlinear vector network analyzer plays a key role to characterize the behavior of mixed signal systems.In order to provide stable harmonic phase reference for NVNA,this paper presents a new phase reference based on multi-tone excitation and studies the prime number selection for stimulus frequency.Firstly,the basic theory of mixed signal system based on X parameters is briefly introduced,including the static X parameter and the dynamic X parameter with long-term memory.The key technologies for parameter extraction platform are analyzed and the correction and calibration of oscilloscope are analyzed.Then,in order to realize the harmonic phase reference,this paper designed the scheme of multi-tone phase reference.The theory formula of amplitude spectrum is deduced to verify the measurement results.The stimulus results of three-evenly spaced tones and three unevenly-spaced tones are compared,and the envelop period for three tone stimulus is relevant to the greatest common divisor of the two intervals.Finally,the paper demonstrates the DAC output characteristics of at sub-Nyquist rate under several DAC construction modes and gives the method to improve the spectrum utilization.The prime number algorithms for selecting single tone and multi-tone stimulus frequency are studied.According to the noise measurement of the oscilloscope,the average results are used to determine the number of ADC and the sub-Nyquist frequency.The target frequency and the resolution frequency are selected to avoid sub-Nyquist frequency by specific constraints.This algorithm has the advantage of improving the effective sampling rate to reconstruct perfect waveform.Finally,the processed results in time domain and frequency domain are analyzed using the measurement data acquired from the oscilloscope.Comparing the results of the prime number frequency with the exact frequency,it is evident that the power and phase match perfectly except the significant difference at integer sub-Nyquist frequency points,which illustrates the prime number algorithm can weaken the effect of noise spectrum.The measurement results indicate that it is of great importance to study the next generation comb generator using the multi-tone stimulus as the phase reference of NVNA.