Microwave-Circuit-Embedded Resin Printed Circuit Board for Short Range Wireless Interfaces

Microwave circuits embedded in a multi-layer resin PCB are demonstrated using low loss resin materials. Resin materials for microwave frequencies were compared with conventional FR-4 with respect to dielectric and conductor loss factors, which proved that losses could be reduced drastically with the low loss material and design optimizations. Baluns, switches and BPFs were designed and fabricated to estimate microwave performances. Measured and simulated insertion losses of the circuits for 2.5 GHz band, were 0.3 dB for a switch, 0.4 dB for a balun and 2.0 dB for a 3-stage Chebyshev BPF. An integration of a switch, a BPF and two baluns was successfully implemented in a multi-layer PCB. Insertion losses of the fabricated integrated circuit were less than 3 dB with 0.1 dB additional loss compared with a sum of individual circuit losses. With estimated results of temperature characteristics and reliability as well as low loss performances, microwave circuits in resin PCBs can be considered as a viable candidate for microwave equipments. key words: microwave, resin, PCB, balun, BPF, loss, integration