A broadband intermodulation reference generator based on artificial nonlinear dipole

Accurate passive intermodulation (IM) test calls for precise IM reference for verifying and evaluating the test error from the tester, which makes the IM calibrator source with a wide working band and dynamic range important. This letter reports on a low-cost and broadband IM generator with a compact area of 5 x 5 cm(2). The broadband IM source is designed and demonstrated on the coplanar waveguide structure, where an artificial nonlinear dipole is used to generate IM reference. In special, the dipole is constructed by a diode (HSMS 2822) and two independent copper islands with optimized size. By controlling the bias voltage across the diode, the IM magnitude level can be changed accordingly. The IM tunable dynamic range is over 47.5 dB that covers GSM 800 MHz, GSM 900 MHz, DCS 1800 MHz, and TD-LTE band. Meanwhile, the obtained IM has an improved IM-bias flat response.