Compact, Non-Invasive, High Impedance Detectors in CMOS for Mm-Wave Applications




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This dissertation investigates uses of mm-wave detectors in complementary metal-oxidesemiconductor (CMOS) for affordable mm-wave circuit characterization. The scaling of CMOS technology has brought significant advances of high frequency capabilities for CMOS integrated circuits. The affordability of CMOS technology, coupled with this ability to operate at the millimeter and sub-millimeter wave frequency range, has opened avenues for many exciting applications with commercial viability. However, going forward the affordability of mm-wave circuits and systems is limited by the test costs and time required to verify the performance. Mm wave measurement testing instruments are expensive because of the high cost of raw materials, limited demand and competition, and the need for customized parts for many applications. On-chip detectors can provide an affordable alternative to high frequency testing. Feasibility of a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) based W-band root-meansquare (RMS) detector for measuring mm-wave voltages using DC measurements is demonstrated in a UMC 65-nm CMOS process. The detector achieves broadband operation from 80-110 GHz with a detector gain of 8.5 V-1 at 60-nA bias. The insertion loss due to the detector relative to a 50-Ω through line is less than 0.15 dB. The compact detector only requires an active area of 20 µm2. Hence, the low power, low loss, compact, broadband and high impedance detectors can be placed at various nodes of circuits for non-invasive voltage measurements. An application of these detectors is measurements of standing wave voltages for characterization of a 280-GHz patch antenna. Several wideband (265GHz -325GHz), high impedance detectors fabricated in a TI 45-nm bulk CMOS process are used to sample the standing wave voltages on a transmission line connected to a 280-GHz patch antenna. The compact detector with an area of 25 µm2 and a responsivity of 70 V/W at 10-nA bias can easily be integrated within the transmission line with virtually no area penalty. Additionally, placing a detector has minimal loading effect as demonstrated by the negligible change of return loss of the structure. Other applications include measurements of the fundamental and second harmonic signals in a frequency doubler using a mode-isolation technique. The effects of second harmonic signal feedback to the input of frequency doubler with an output frequency of 180 GHz is verified using these detectors and a mode-isolation technique. Low loss detectors are placed in a frequency doubler driven by an amplifier. Using the detectors, various circuit properties such as amplitude match between signals on a differential line, optimum biasing point, voltage gain and frequency response are characterized and optimized.



Metal oxide semiconductors, Complementary, Metal oxide semiconductor field-effect transistors, Millimeter wave devices, Detectors--Design and construction


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