The quantity traceability of the modulation analyzer is achieved by modulation comparison. During modulation comparison, the modulation analyzers measure the AM and FM signals generate by the same signal generator, and the differences of modulation accuracy, modulation distortion and residual modulation are compared. An AM and FM test source with very stable modulation quantity and extremely low modulation distortion is needed. We can get a high performance AM and FM signal by using Matlab generates AM and FM waveform data and then using a high performance arbitrary waveform generator to playbacks it. Experiments show that the modulation stability of the signal is less than 0.5%, the distortion of AM is less than 0.3%, the distortion of FM is less than 0.1%, the residual AM is less than 0.01% and the residual FM is less than 1 Hz. The performance of the AM and FM signal generates by arbitrary waveform generator is better than that generates by traditional analog AM and FM test source, and it fully meets the requirements of modulation comparison.