DESIGN AND FABRICATION OF ON CHIP MICROWAVE PULSE POWER DETECTORS

On-chip microwave pulse-power detectors are promising devices for many electrical systems of both military and commercial applications. Most research in microwave power detector design have been focused on thermal power detectors, such as thermistors or thermocouples, due to their wide dynamic range and high frequency operation. However, due to their slow thermal response time, it is impossible to detect microwave pulses with a few micro or sub-micro seconds of pulse width. Schottky diode power detectors are the best candidates for this purpose due to their fast pulse response time and small size. We have developed a means for fabricating Schottky diodes as part of any Complementary-Metal-Oxide-Semiconductor (CMOS) process by modifying the layout file. CMOS Schottky diodes were added at pre-selected locations through a CMOS process. We have also developed a process for adding or deleting Schottky diodes on a CMOS fabricated chip by using Focused Ion Beam (FIB). FIB milling and ion induced deposition were used for adding or deleting Schottky diodes at any desired location on a CMOS-fabricated chip as a post-CMOS process. Spice models of CMOS Schottky diodes were developed and used for designing the RF front end circuits in passive RF circuits. MOSFET based RF pulsed power detector circuits were also designed and fabricated. Fabricated power detectors were tested under direct injection and radiation of microwave pulse signals. Measured results for fabricated CMOS Schottky diodes, FIB Schottky diodes and MOSFET half-wave and full-wave rectifier circuits are summarized in a table with the pulse response time, the dynamic range, the sensitivity, and the frequency response to determine which power detector is the best choice for detecting a specific source signal

Optimization of CMOS MEMS Microwave Power Sensors

Abstract- Micromachined power sensors with operation up to 50 GHz were recently achieved in CMOS technology [1]. To improve their sensitivity and signal-to-noise ratio, while maintaining microwave performance, several design parameters must be considered, such as the number and placement of thermocouples. This paper presents experimental and analytical thermal characterization of the sensors, which provides insight into the proper adjustment of the layout parameters. Experimental results were obtained by indirect measurements of the sensor temperature distribution under various applied power conditions. A simple and approximate model was developed, and adjusted based on experimental results, which was then used to show the effects of the variations in layout parameters on the overall device sensitivity. The model includes thermoelectric Peltier and Thomson effects. I