W-Band Gallium Nitride MMIC Amplifiers for Cloud Doppler Radar Arrays

We present an effort in developing W-band (75-110 GHz) gallium nitride (GaN) monolithic microwave integrated circuit (MMIC) amplifiers for radar arrays. Due to GaN's high electric field breakdown capability and good 2D electron gas mobility in heterostructure field effect transistors, GaN power amplifiers provide best performance for high output power, high efficiency and small MMIC form factor amplifiers at W-band frequencies. GaN low noise amplifiers can also provide large receiver input dynamic range, reduce receiver noise figure and can be more tolerant of input power leakage from the transmitter without the need of protective limiter circuitry. All these characteristics are crucial for high frequency arrays where design require small circuit spacings, high efficiency to reduce power consumption and heating, and the minimization of circuit components for manufacturability and reliability. We will discuss results of power, driver and low noise amplifiers that we have designed, fabricated and characterized for radar array applications.