Improved 240-GHz subharmonically pumped planar Schottky diode mixers for space-borne applications

Low-noise broad intermediate frequency (IF) band 240-GHz subharmonically pu mped planar Schottky diode mixers for space-borne radiometers have been dev eloped and characterized, The planar GaAs Schottky diodes are fully integra ted with the RF/IF filter circuitry via the quartz-substrate upside-down in tegrated device (QUID) process resulting in a robust and easily handled pac kage, ii best double-sideband-mixer noise temperature of 490 K was achieved with 3 mW of local-oscillator power at 2-GHz IF. Over an IF band of 1.5-10 GHz, the noise temperature is below 1000 K, This state-of-the-art performa nce is attributed to lower parasitic capacitance devices and a low-loss wav eguide circuit, Device fabrication technology and the resulting RF mixer pe rformance obtained in the 200-250-GHz frequency range will be described.