A High Isolation Switch Circuit Design Based on HTCC

keywords:isolation cavity  high-temperature co-fired ceramics  cascade switch circuit

Abstract:Switch circuit based on the switch chip is the basic unit of radio frequency front-end circuits, which can achieve radio frequency signal on and off and is widely used in low-power radio frequency signal transmission. In this paper, a high isolation switch circuit based on the high-temperature co-fired ceramics substrate and the cascaded isolation cavity, formed by cascaded switch chips as the basic circuit is designed. The frequency is 6 GHz~ 15 GHz and the isolation index is 60 dB. The switch circuit consists of a limiter chip and two absorption type gallium arsenide single-pole single throw switches, which are assembled in two adjacent isolation cavity structures, and transitioned to a symmetrical stripline transmission structure inside the substrate through the coaxial-like vertical transmission, supplemented by ground holes on both sides to achieve electromagnetic shielding. The electromagnetic field modeling and simulation of the switch circuit show that it has good transmission and isolation characteristics. After the radio frequency front-end circuit is manufactured, the switch circuit is assembled and tested. The test results are consistent with the modeling and simulation results, verifying the high isolation switch circuit design in this paper.