The application of nanofabrication techniques such as molecular-beam epitaxy, electron-beam lithography, and selective reactive ion etching, to metal-semiconductor field-effect transistor (MESFET), high electron mobility transistor (HEMT), and monolithic microwave integrated circuit (MMIC) fabrication allows precise control of physical device parameters such as layer thickness, doping density, and gate length. Such well characterized, flexible, and accurate technologies allow high performance devices and circuits to be fabricated with predictable yield. The application of nanofabrication techniques to both low noise, 0.2 mum mushroom gate, GaAs/Al0.3Ga0.7As MESFETs and MMICs is demonstrated. The MESFETs have 0.75 dB noise figure and 11 dB associated gain at 12 GHz; while the MMICs have "right-first-time" performance with more than 15 dB gain at 44 GHz. It is also shown that these techniques are applicable to pseudomorphic HEMTs and predicted that the use of nanofabrication in general and selective reactive ion etching in particular, will be essential to the implementation of MMICs working at frequencies of 100 GHz and beyond.