The RF output of a wireless networking chip is found to generate ±80 MHz harmonics, which are located outside the 2.4 GHz ~ 2.5 GHz WLAN operating frequency range, during the power-on IQ calibration process. These harmonics are found to originate from the 80 MHz sampling frequency used by the baseband processor. Experimental results show that the parameters can be adjusted via the TX IQ, RX IQ and VGA (Variable Gain Control Amplifier) parameter adjustment, and thus achieve the purpose of no output harmonic, although these adjustments can solve the harmonic problem, their uses are constrained to not causing frequency offset and signal quality issues.