Design of Q-band Transceiver Front-end Module

This paper presents a Q-band transceiver front-end module employing a superheterodyne structure, which includes transmitting circuits and receiving circuits. As for the proposed transceiver fronted-end module, intermediate frequency is fixed at 5.8GHz, the local oscillator (LO) frequency is 34.7-37.7GHz and the LO and IF signal are mixed to obtain a radio frequency(RF) signal operating at 40.5-43.5GHz. In order to suppress the spurious signals, the high-performance LO filter and RF filter are proposed in this paper. The LO filter works at a frequency ranging from 34.5GHz to 39GHz, the measured insertion loss (IL) is less than 3.2dB and return loss (RL) is better than 14dB. Besides, the RF filter works over the operating band of 40.5-43.5GHz, the measured IL is less than 4.3dB and RL is better than 13.8dB. As for the receiving circuits, a -30dB coupler is presented to weaken the strength of the RF signal, the coupling flatness is better than 1dB in the frequency range of 40.5-43.5GHz. In addition, the link budget of the overall circuits are given as follows.