Title :
A GaAs monolithic array of impedance matched antenna/detector pixels for a 94 GHz imaging system
Author :
Henry, H.G. ; Freitag, R.G. ; Shaller, R.R. ; Cohn, M.
Author_Institution :
Westinghouse Adv. Technol. Lab., Baltimore, MD, USA
Abstract :
The design, fabrication, and performance of a 4*4 pixel array of monolithic GaAs 94-GHz detector circuits is described. This large chip is developed to be a tile for much larger arrays consisting of thousands of pixels for 94-GHz imaging. Each pixel is a slot antenna on one face coupled through the GaAs to a microstrip circuit containing a Schottky-barrier diode on the opposite face. The microstrip circuit provides an optimum impedance match between the diode and the slot antenna so that no additional tuning to free space is required. The diode is fabricated using a selective ion implantation process optimized for uniformity, repeatability, and yield, and has zero-bias capacitance and series resistance, respectively, of 14 fF and 15 Omega . Process control is essential, because variations in diode parameters can mismatch and detune the circuit. With the diode optimally forward-biased for square-law operation and a video bandwidth of 1 MHz, the tangential signal sensitivity (TSS) peaked in the 92-96-GHz range and was always better than -50 dBm at 94 GHz.<>
Keywords :
III-V semiconductors; MMIC; detector circuits; gallium arsenide; image sensors; impedance matching; microwave detectors; microwave imaging; waveguide antennas; 1 MHz; 14 fF; 15 ohm; 16 pixels; 4 pixels; 94 GHz; GaAs monolithic array; Schottky-barrier diode; detector circuits; diode parameters; imaging system; impedance matched antenna/detector pixels; microstrip circuit; optimum impedance match; repeatability; selective ion implantation process; series resistance; slot antenna; square-law operation; tangential signal sensitivity; uniformity; video bandwidth; yield; zero-bias capacitance; Antenna arrays; Circuits; Detectors; Gallium arsenide; Impedance; Microstrip antenna arrays; Microstrip antennas; Schottky diodes; Sensor arrays; Slot antennas;
Conference_Titel :
Electron Devices Meeting, 1989. IEDM '89. Technical Digest., International
Conference_Location :
Washington, DC, USA
Print_ISBN :
0-7803-0817-4
DOI :
10.1109/IEDM.1989.74256
