Sb-heterostructure Diodes Research Articles

W-Band Sb-Diode Detector MMICs for Passive Millimeter Wave Imaging

A W-band monolithic microwave integrated circuit (MMIC), including an Sb-heterostructure diode on a GaAs substrate, has been demonstrated. The MMIC also includes the RF choke and output shorting capacitor essential to detector circuits. Additional input matching has yielded peak sensitivities on the order of 10 000 V/W and equivalent bandwidths of 40 GHz. Using these circuits in conjunction with current W-band low-noise amplifier technology can achieve the sub-1degK noise equivalent temperature difference necessary for producing discernible images with W-band passive imaging cameras.

1$/f$ Noise of Sb-Heterostructure Diodes for Pre-Amplified Detection

The 1/f noise of a series of Sb-heterostructure diodes with varying area has been measured. Standard power law formulas for the frequency and voltage dependence were found adequate to summarize the data. An inverse dependence of voltage noise spectral density on the area was determined, consistent with the simple resistor model. Simulations using the noise formula predict that pre-amplification gain in the 30 to 35 db range can produce a sub-1degK noise equivalent temperature difference in realistic imaging cameras

W-band direct detection circuit performance with Sb-heterostructure diodes

W-band direct detection circuits have been designed and fabricated for use in a passive millimeter wave camera. The circuits are based on the recently developed Sb-heterostructure diode. We measure record voltage responsivities in test circuits, up to 8,000 mV/mW from 75 to 93 GHz, with input power from -50 to -30 dBm. Performance was similar in an actual camera frequency processor board with 128 tuned channels. 72% of detectors showed responsivity at or above 6,000 mV/mW and 3% of channels were above 10,000 mV/mW. Since tens of thousands of Sb-heterostructure diodes can be reproducibly and inexpensively fabricated, this demonstrates for the first time the feasibility of large-scale detector arrays utilizing zero bias direct detection circuitry.