This paper presents the design of a 205-GHz amplifier with 17.8-dB measured gain, 24-GHz 3-dB bandwidth (BW), and 18-mW DC power consumption in 130-nm SiGe BiCMOS technology. The amplifier is optimized for low DC power consumption in millimetre-wave wireless applications. By properly biasing the transistors in the soft-saturation region, a high maximum available gain (MAG) can be obtained for low DC power consumption. A distributed decoupling capacitor composed of metal-insulator-metal (MIM) capacitors and embedded metal-oxide-metal (MOM) capacitors is proposed for the on-chip DC-distribution network to provide low impedance to ground for AC and reduced DC loss. The performance of this distributed design can be analyzed with the synthetic transmission line model, and is verified from 140 GHz to 290 GHz by a fabricated test structure. The fabricated amplifier has an area of 900 430