A $W$ -Band Monolithic Integrated Active Hot and Cold Noise Source

For application in radiometry or noise measurement systems, an integrated active hot-cold load (AHCL) operating in the W-band (75-110 GHz) is presented and realized as monolithic millimeter-wave integrated circuit (MMIC). It makes use of a novel circuit topology that employs only a single active noise source and monolithic integrated switches to provide a cold and a hot noise reference temperature. The AHCL provides a measured cold temperature of only 230 K and a hot temperature of 860 K around 94 GHz, thus enabling two-point radiometric calibration and absolute power measurements. The noise source of the AHCL has been fabricated as a two-port test structure too. In that configuration, it has been measured as a low-noise amplifier with a noise figure of 2.5 dB at 94 GHz proving its good noise performance. As a standalone active cold load (ACL), an excellent noise power of only 190 K at 93 GHz is achieved. The AHCL and ACL MMICs have been fabricated in 100-nm gate-length metamorphic high electron-mobility transistor technology.