Sb-Heterostructure Low Noise W-Band Detector Diode Sensitivity Measurements

Sb-heterostructure diodes have become the detector of choice for W-band millimeter wave imaging cameras. Here we demonstrate lower impedance versions that optimize noise equivalent power (NEP). The goal is to decrease the gain required of the RF pre-amplifier, ideally to zero. Measured W-band sensitivities for three diodes are 3500, 5500, and 6000 V/W. Their zero bias differential resistance values imply Johnson noise limited NEP´s of 0.98, 0.83, and 0.79 pW/Hz^frac12, respectively, much less than obtained from conventional Schottky diodes. A wideband transition from a horn antenna to the 6000 V/W detector has produced an integrated bandwidth of 30 GHz with implied temperature sensitivity (NEDeltaT) close to 10degK