Front-end Monolithic Microwave Integrated Circuits (MMICs) have recently become commercially available for frequencies above 100 GHz. However, achieving low-loss and broadband interconnections between the antenna and MMICs is challenging for integrated front ends at these frequencies. This thesis presents the characterization of a flip-chip interconnection used for an integrated front end at 150 GHz (G-band) with an on-package leaky-wave dual lens antenna. Two paths for the front-end integration have been proposed. The first path adopts CPW transmission lines on 500 μm-thick fused silica and provides easy assembly and seamless flip-chip capabilities. The second uses microstrip transmission lines on 50 μm-thick fused silica and provides lower transmission line loss but a challenging assembly and flip-chip interconnection. In this thesis, a path toward microstrip and CPW flip-chip interconnections has been outlined at the high millimeter-wave frequencies. Two-port test structures using CPW transmission lines were developed, adopting a double Thru-Reflect-Line calibration and allowing for accurate extracting of the interconnection response. The final interconnection to the MMICs has been realized using a via-less CPW to microstrip transition with high impedance transmission line S11 matching compensation. The simulated S11 and S22 are below -12 dB, Ohmic loss below 0.6 dB, radiation loss below 0.4 dB, and transmission line losses around 0.15 dB/mm.

This thesis presents a resonant sensor circuit design that converts the deformation of a load cell in a conveyor belt into a change in resonance frequency. The sensor is inductively coupled to a reader circuit using planar PCB inductor coils. A sensor circuit was designed, fitted on a square PCB with 14.14 mm side length. The circuit consists of a planar squared inductor and a planar interdigital capacitor. The inductor has an inductance of 0.66535 $\mu$H, and the capacitor has a capacitance of 5.157 pF. An additional SMD capacitor was added to reach a resonating frequency range around 27.2 MHz. The deformation of the load cell causes a bend in the sensor PCB, which is directly attached to the diaphragm of the load cell. The bend causes a change in capacitance of the interdigital capacitor, which shifts the resonance frequency of the sensor. The sensor components are designed in MATLAB and simulated and verified in CST studio.