A digital frequency characteristic analyzer based on orthogonal modulation principle is developed using steady-state response measurement method.The frequency response analyzer consists of Direct Digital frequency Synthesis(DDS),analog multiplier,low pass filter,and low power consumption MCU.The MCU is employed as main control unit to carry out overall control and digital signal processing.The sine wave over the full frequency range is output through the integrated DDS chip.The analyzer system samples and digitalizes the input signal and output response,hence the amplitude and phase frequency characteristics are obtained.An RLC network is chosen to test the frequency characteristic analyzer.Measurement results show that the center frequency error is not more than 0.2%,the absolute value of quality factor error is less than 1.25%,and the maximum voltage gain is larger than -1 dB.Both the input and output impedance of the frequency characteristic analyzer are 50 Ω,and the absolute value of measurement errors are less than 0.5dB and 3° for amplitude frequency and phase frequency,respectively.The analyzer is suitable for characteristic parameter measurement of micromechanical resonant sensor.