High Q Inductors Fabricated on Glass Substrates for RF Applications

This paper presents the implementation of a high-Q inductor using the thick metal glass integrated passive device (IPD) process and its application in RF devices. Glass substrates offer superior insulation properties compared to silicon substrates, making them an economical choice for realizing high-quality, low-loss components. The inductor, fabricated using the thick metal glass IPD process, demonstrates a high Q-factor of 40. In addition, by improving the conventional IPD process and employing a thick metal IPD process to increase the thickness of the inductor body, we have managed to reduce resistance loss. This enhancement led to a further improved Q-factor of 46 for the glass inductor processed using the thick metal IPD method. Utilizing these advancements, a low-loss glass Lange coupler and a high-efficiency power amplifier (PA) were fabricated. The characteristics of the glass Lange coupler include an insertion loss of 0.3 dB, amplitude imbalance of 0.07 dB, and phase imbalance of 1.25° at the center frequency of 8.4 GHz. The characteristics of the glass PA include a small-signal gain of about 13.4 dB and a return loss of more than 17.5 dB at 9.4 GHz. The PA has a saturation power of 38.2 dBm with a drain efficiency of 62.1% under a 10% duty pulse condition at 9.4 GHz.