Evaluation of variable components and detectors for millimeter-wave circuits

To overcome the variability of nano-scale transistors and uncertainty of transistor and passive component models for mm-wave circuit design, incorporation of tunability and sensing capability has been investigated. In particular, this dissertation work evaluated variable components (varactor and variable inductor), and voltage detector (Shottky Barrier Diode voltage detector) and their use in millimeter wave power amplifiers. Compared to a simple resonator composed of an inductor in parallel with a varactor, a resonator using a transformer based variable inductor using magnetic coupling shows higher Q factors but a narrower tuning range. To further increase the tuning range of variable inductors, a double secondary variable inductor is proposed and measured. Measured effective inductance varies from 39 to 47.4 pH (8.4 pH, 19.6 %) while measured Q factor varies from 4.0 to 2.4 at 80 GHz. An approach for extracting a compact model for the structure from measurements is proposed and verified. This method utilizes a "divide and conquer" concept based on measurements of six different test structures.;A two stage mm-wave power amplifier in a 45-nm digital CMOS (Complementary Metal-Oxide Semiconductor) process is designed and characterized. The input, inter-stage and output matching networks are designed to minimize the losses resulting from both components and mis-match. The power amplifier has the measured peak output power of 9.1 dBm, 7.7 % PAE (power added efficiency) at 78 GHz. New root mean square (RMS) voltage detectors with increased impedance are incorporated into a mm-wave tunable PA (power amplifier) circuit, along with a new double secondary variable inductor. Addition of tunability reduces the peak small signal gain by 4.3 dB while reducing the output power at peak PAE and PAE by 1.4 dB and 2.8 % at 78 GHz, respectively. Adding the detectors to the tunable PA has no measurable impact on the performance. The integrated voltage detectors are used to understand the internal circuit behaviors. Using the outputs of detectors, the optimum load impedance for the highest power gain and output power can be determined.