Steps to test the haa9802 chip:
Power supply test: check whether the chip is normally powered and the voltage is stable.
Input signal test: The input signal of a known frequency is connected to the input pin of the chip, and the output signal is observed with an oscilloscope.
Output signal test: Check whether the frequency, amplitude and phase of the output signal are consistent with the input signal.
Troubleshooting: If the output signal does not meet expectations, it may be a chip damage or circuit board problem that requires further inspection.