A Study on the Memory Effect of Mixer

Abstract

As we know, with the increase of input signal bandwidth, the asymmetry of upper and lower sideband of the third-order intermodulation distortion (IMD) will become more evident. The industry describes this asymmetric phenomenon as the memory effect of the microwave component. For simplicity, the third-order intermodulation distortion (IM3), the major part of IMD, is chosen in investigating the conditions for IMD asymmetry. With the rapid communication systems, the bandwidth of the input signal becomes wider and wider, and the memory effect becomes very significant. Therefore, it's necessary to study the asymmetry of IM3. Today, taking the advantages of three signal generators and a spectrum analyzer, the first investigation into the effect of different excitation conditions to the memory effect of double balanced diode mixer. The different excitation conditions include frequency separation, the power of the radio-frequency (RF) signal and the local oscillator (LO) signal, and so on. For the first time, the measurement results show the impact of the input signal (LO signal and RF signal) power and the relative size of LO frequency and RF frequency on mixer memory effect.