65 GHz small-signal-bandwidth switched emitter follower in InP heterojunction bipolar transistors

Two Switched Emitter Follower circuits are designed and fabricated with a 320 GHz-Ft-InP Double Heterojunction Bipolar Transistors process (DHBT). The first one uses a 10μm emitter length (T10) transistors and the second a 7μm emitter length (T7) transistors. Measurements show a−3dB small signal bandwidth up to 55GHz with a sufficient isolation larger than 30dB. An extensive analysis as function of sizes, hold capacitor and bias conditions were performed by simulations in order to obtain a good tradeoff between bandwidth, isolation and linearity.