Lih-Jen Hou

This work investigates a low-power transimpedance amplifier (TIA) topology suited for VHF micromechanical oscillator applications. The TIA circuit comprises of a regulated-cascode (RGC) transimpedance gain stage and an inverter-based wideband Cherry-Hooper amplifier with capacitive peaking. The circuit was designed using TSMC 0.18μm CMOS technology, exhibiting mid-band gain of 99dBμ and 3dB bandwidth of 280MHz while dissipating only 1.57mW from a 1.5V supply. A linear RLC equivalent model… Show more

This work investigates a low-power transimpedance amplifier (TIA) topology suited for VHF micromechanical oscillator applications. The TIA circuit comprises of a regulated-cascode (RGC) transimpedance gain stage and an inverter-based wideband Cherry-Hooper amplifier with capacitive peaking. The circuit was designed using TSMC 0.18μm CMOS technology, exhibiting mid-band gain of 99dBμ and 3dB bandwidth of 280MHz while dissipating only 1.57mW from a 1.5V supply. A linear RLC equivalent model extracted from a practical 48MHz Lamé-mode resonator with Q>;40,000 was interfaced with the TIA circuit in a series-resonant oscillator configuration, showing simulated phase-noise less than -128dBc/Hz at 1kHz offset. Show less

A two-port silicon-based micromechanical beam resonator driven at its high-stiffness locations has been proposed with enhanced power handling as compared with the same resonator but using conventional drive/sense configurations. The key to attaining superior power handling relies on the electrode arrangements where critical handling power (or Duffing-nonlinear bifurcation power) becomes much higher by driving the resonator at its high-stiffness locations than low-stiffness areas. In this work… Show more

A two-port silicon-based micromechanical beam resonator driven at its high-stiffness locations has been proposed with enhanced power handling as compared with the same resonator but using conventional drive/sense configurations. The key to attaining superior power handling relies on the electrode arrangements where critical handling power (or Duffing-nonlinear bifurcation power) becomes much higher by driving the resonator at its high-stiffness locations than low-stiffness areas. In this work, resonators using high-stiffness driving approach exhibit around 20X (20 times) power handling improvement as compared to low-stiffness driving counterpart while the motional impedances in both cases are the same under linear operation. Show less

Deep-submicrometer-gap CMOS-MEMS “composite” resonators fabricated using 0.18- μm-1-poly-6-metal foundry CMOS technology have been demonstrated for the first time to substantially improve their electromechanical coupling coefficient, hence leading to a motional impedance of only 880 kΩ at 15.3 MHz. A simple maskless wet release process has been successfully transferred from a 0.35- μm platform to an advanced 0.18-μm version, capable of offering enhanced gap spacing and transduction area for… Show more

Deep-submicrometer-gap CMOS-MEMS “composite” resonators fabricated using 0.18- μm-1-poly-6-metal foundry CMOS technology have been demonstrated for the first time to substantially improve their electromechanical coupling coefficient, hence leading to a motional impedance of only 880 kΩ at 15.3 MHz. A simple maskless wet release process has been successfully transferred from a 0.35- μm platform to an advanced 0.18-μm version, capable of offering enhanced gap spacing and transduction area for CMOS-MEMS resonators monolithically integrated with high-performance CMOS circuitry. This proposed platform offers ease of use, fast turnaround time, low cost, convenient prototyping, and inherent MEMS-circuit integration, therefore showing great potential toward future integrated sensing and single-chip RF applications. Show less

A two-port micromechanical beam resonator driven by its high stiffness locations has been used to enable a series-resonant resonator oscillator, for the first time, with enhanced power handling and phase noise performance as compared with the same resonator design but using low-stiffness driving configuration. The key to attaining better power handling capability relies on driving electrode arrangement where critical handling power becomes much larger by driving the resonator at its… Show more

A two-port micromechanical beam resonator driven by its high stiffness locations has been used to enable a series-resonant resonator oscillator, for the first time, with enhanced power handling and phase noise performance as compared with the same resonator design but using low-stiffness driving configuration. The key to attaining better power handling capability relies on driving electrode arrangement where critical handling power becomes much larger by driving the resonator at its high-stiffness locations than low-stiffness areas since power handling of
a resonator is proportional to its effective stiffness. With 16.9X improvement on power handling capability for a 9.7-MHz beam resonator via the proposed high-stiffness driving concept, a MEMS-based oscillator referenced to it greatly benefit from power handling enhancement, therefore leading to 26.5 dB reduction in far-from-carrier phase noise as compared to its low-stiffness driving counterpart. Show less