Background: In-phase/Quadrature (I/Q) demodulation technology is widely used in radio frequency signal phase control system. As the intrinsic errors in hardware

such as the imbalances of gain and phase in 90° hybrid and 0° hybrid

direct current (DC) offsets and phase errors from length difference of circuits

the output signal is an ellipse and the output phase is nonlinear to the input radio frequency (RF) signal. The detection of phase precision is influenced. Purpose: This study aims to reduce the effects of errors existed in the I/Q demodulators. Methods: A calibration method for I/Q demodulation technique is proposed and applied to research and development of I/Q integrate circuits

which is based on the surface mounted devices (SMD) chip. Results: Experimental tests showed that the phase error was less than ±0.15°

the amplitude stability was less than ±1%

and the channel delay was less than 10 ns. Conclusion: This calibration method

together with the designed circuit board for the RF signal front end preprocessing can reduce the effects of intrinsic errors efficiently. It has been being used in upgrading of beam trip diagnostic system in the storage ring of Shanghai Synchrotron Radiation Facility (SSRF). Abstract