A Full-Duplex Bidirectional Amplifier With Low DC Power Consumption Using Tunnel Diodes

A low-power, switchless, full-duplex bidirectional amplifier operating in the 915 MHz (industrial, scientific and medical band) is proposed. It is composed of two identical reflection amplifiers and one 90°, -3 dB branch line coupler (BLC). The reflection amplifiers are designed using low dc power consumption tunnel diodes and provide a measured reflection gain of 13 dB with consumed power of only 178 μW for -30 dBm of incident signal power. These reflection amplifiers are integrated with a miniaturized BLC to form a bidirectional amplifier that provides 9 dB of measured transmission gain and 22 dB of measured return loss.