Extremely low power transmitter/receiver GaAs MMIC circuits at L band

The authors have developed an enhancement GaAs monolithic microwave integrated circuit (MMIC) process which is capable of producing very-low-power, highly efficient transmitting/receiving circuits which can be operated from unipolar 3-V batteries. They have demonstrated key circuits such as a surface acoustic wave (SAW) locked oscillator, a variable-gain 180 degrees phase shifter, and a variable-gain power amplifier. The amplifier required a DC current of 4 mA and delivered 4 dBm to 50- Omega loads with greater than 25 dB of gain. The process is capable of producing high-gain devices with low knee voltages of less than 1 V which pinch-off at 0 V. The very low substrate losses and current leaks associated with the process allow design of RF circuits in high-impedance environments.<>