The Co-Design of Broadband Diplexer and Quasi-Reflectionless Lowpass/Highpass TFIPD Filter Chip

A new ultra-miniaturized 5G N78 and N79 diplexer based on GaAs Thin Film Integrated Passive Device (TFIPD) technology is proposed in this brief. By a NiCr thin film resistor, the quasi-reflectionless lowpass/highpass filter can also be achieved on the same circuit structure without any increase of size. Circuit schematic is composed of serial-parallel inductances and capacitances, which generates out-of-band transmission zeros. The proposed design provides <2 dB insertion loss and >15 dB out-of-band rejection. Therefore, the GaAs-based TFIPD technology can support low-loss, high-precision, and miniaturized design desires of 5G radio-frequency (RF) front-end devices. Chip model is demonstrated through EM simulation, wafer fabrication, and measurement.