A K/Ka-band distributed power amplifier with capacitive drain coupling

A 14 to 37-GHz monolithic microwave integrated-circuit (MMIC) distributed-power amplifier is described that has three FETs (field-effect transistors) of varying periphery, all capacitively coupled to the gate line. The capacitor is inserted between the drain line and the drain of any FET seeing a low or negative impedance. This deceases drain line loading and increases the impedance at the drains. High total-FET-periphery can be accommodated, achieving higher output power. A 4-dB gain was achieved from 14 to 37 GHz. Output power of 20 dBm or greater has been demonstrated at frequencies up to 33 GHz at 1 dB compression. A maximum 1-dB compressed output power of 23.5 dBm (220 mw) has been measured at 26 GHz. The circuit is truly monolithic, with all bias and matching circuitry included on the chip.<>