A Highly Linear InP Distributed Amplifier Using Ultra-wideband Intermodulation Feedforward Linearization

We demonstrate a highly linear wideband distributed amplifier (DA). For the first time, an intermodulation feedforward linearization technique is introduced in a distributed structure to achieve a very wideband linear amplifier. The proposed circuit is designed and fabricated in an Indium Phosphide (InP) Heterojunction bipolar transistor (HBT) process. The measured results exhibit an average 10 dB of gain with a 3-dB bandwidth that extends from dc to 90 GHz. The maximum output 1-dB compression power $\mathbf{(P_{\mathrm{1dB}})}$ is 20.5 dBm, and output third-order intercept point (OIP3) is 33 dBm, respectively. Compared to a conventional design, the power and linearity of the linearized DA are enhanced significantly over a very wide frequency range from dc to 65 GHz while maintaining low power consumption.