Double N Stubs for Impedance Matching Improvement of Pogo Pin Test Board at mmWave Applications

Function testing of radio frequency integrated circuits (RFICs) is a vital step to confirm the reliability of RFICs during mass production. However, impedance mismatching occurs because of discontinuous routing inside test boards, which are an important device in RFIC testing. Double N stubs (DNS) are proposed for replacing the conventional lumped components to improve the impedance matching of test boards. DNS can be analytically designed on the printed circuit board (PCB) trace of the load board. Experiments were conducted to validate this mechanism for effectively improving the reflection coefficient of test boards at mmWave bands such as 28 and 55 GHz.