Wideband MMIC Power Limiters for Integrated Receivers

Abstract

This thesis explores the feasibility of designing wideband power limiter circuits that can be manufactured using monolithic microwave integrated circuit (MMIC) technologies, with a primary focus on gallium nitride (GaN). Three complete limiter circuits have been designed and simulated with different performances, along with one limiter needing external activation. No measurements of the circuits have been made. Three of the designs were made for a 0.15 μm GaN process, and the last for a GaAs process incorporating PIN diodes. The GaN-based limiters use switchtransistors to achieve the limiting behavior with different means of activation, and are designed to operate in the 2−6 GHz frequency band. The minimum frequency is limited by the leakage power level, and the upper frequency by small-signal performance. The most promising complete GaN limiter keeps the leakage below 25dBm for input powers up to 50dBm. The GaAs limiter utilizes PIN diodes in an antiparallel configuration to achieve limiting. It operates in the 2 − 18 GHz range, making it a suitable option when this type of process is available. The leakage is below 17.5dBm for input powers up to 48dBm. It is, however, unclear whether the limiter itself will survive powers that large. Although the designs presented here seem to perform well in terms of power and bandwidth, the insertion losses are slightly higher than what is generally accepted.