A monolithic dc-31 GHz distributed amplifier (DA) using cascode heterojunction bipolar transistor (HBT) - n-channel metal-oxide-semiconductor field-effect transistor (NMOSFET) gain cell in 0.18 μm SiGe process is presented in this paper. A HBT-NMOS cascode topology is employed as the gain stage of the DA due to its high cutoff frequency of the input matching transmission line and low Miller effect. The m-derived network and inductive peaking technique are adopted to further extend the bandwidth of the DA, and the dc bias network is also integrated in the chip. Between dc and 31 GHz, the proposed DA demonstrates an average small signal gain of 8.2 dB, and an output 1-dB compression point (P1dB) of 8 dBm. Moreover, the DA is successfully evaluated with eye diagram measurement up to 12.5 Gbps.