Cascaded Constructive Wave Amplification

A high-frequency amplifier technique is introduced based on traveling-wave amplification. As opposed to distributing amplifiers to support traveling waves, the proposed technique amplifies forward traveling waves while attenuating backward traveling waves through a cascade of stages that share a single transmission line. The behavior of the cascaded constructive wave amplifier is analyzed in terms of gain, bandwidth, stability, and noise figure. The amplifier is demonstrated in a 0.12-?? m SiGe BiCMOS process with 12 cascaded amplification stages and achieves more than 26 dB of gain at 99 GHz with a 3-dB bandwidth of 13 GHz. The input and output return loss is better than 15 and 12 dB, respectively. The noise figure of the amplifier is 10.8 dB at 85 GHz. The output-referred P1 dB is -0.1 dBm and the amplifier consumes 113 mW, including current biasing.