J.S. Yuan

Hot-carrier and soft-breakdown effects on VCO performance

This paper systematically investigates the hot carrier and soft-breakdown induced performance degradation in a CMOS voltage-controlled oscillator used in phase locked loop frequency synthesizers. After deriving the closed-form equations to predict phase noise and VCO gain, we relate VCO RF performance such as phase noise, tuning range and gain of VCO subject to electrical stress. The circuit degradations predicted by analytical model equations are verified by SpectraRF simulation using parameters extracted from the experimental data of 0.16 /spl mu/m CMOS technology.

Effect of gate-oxide breakdown on RF performance

The degradation of S-parameters of 0.16-/spl mu/m nMOS devices due to gate-oxide breakdown is examined. An equivalent circuit model for MOSFETs after gate-oxide breakdown is proposed. The influence of nMOSFET gate-oxide breakdown on the performance of a low-noise amplifier is studied using the equivalent circuit model. Depending on which device and how many fingers break down, the circuit continues to work, despite the fact that the performance of S-parameters and noise figure degrades significantly.

Low-power CMOS wireless MEMS motion sensor for physiological activity monitoring

In this paper, a short distance wireless sensor node AccuMicroMotion for physiological activity monitoring is proposed for detecting motions in six degrees of freedom. System architecture, relevant microstructures, and electronic circuits to implement the sensor node are presented. A three-axis microelectromechanical systems (MEMS) accelerometer and a z-axis gyroscope are designed and fabricated using a new deep-reactive ion-etch CMOS-MEMS process. The interface circuits, an analog-to-digital converter, and a wireless transmitter are designed using Taiwan Semiconductor Manufacturing Company 0.35-/spl mu/m CMOS process, wherein the interface circuits adopt chopper stabilization technique and can resolve a signal (dc to 1 kHz) as low as 200 nV from the microsensors; digitized outputs from the microsensors are transmitted by a 900-MHz amplitude-shift-keying radio-frequency transmitter that delivers a 2.2-mW power to a 50-/spl Omega/ antenna. The system draws an average current of 4.8 mA from a 3-V supply when six sensors are in operation simultaneously and provides an overall 60-dB dynamic range.

CMOS RF and DC reliability subject to hot carrier stress and oxide soft breakdown

Hot carrier and soft breakdown effects are evaluated experimentally. A methodology to systematically study hot carrier and soft breakdown effects on RF circuits is developed. Device stress measurement and SpectreRF simulation are conducted to evaluate the impact of hot carrier and soft breakdown effects on RF circuits such as low-noise amplifier and voltage-controlled oscillator performances. Two design techniques to build reliable RF circuits are proposed.

Effect of gate oxide breakdown on RF device and circuit performance

The degradation of S-parameters of 0.16 /spl mu/m NMOS devices due to gate oxide breakdown is examined. An equivalent circuit model for MOSFETs after gate oxide breakdown is proposed. The influence of nMOSFET breakdown on the performance of a low noise amplifier is studied using the equivalent circuit model. Depending on which device and how many fingers breakdown, there is a nonzero probability that the circuit continues to work, in spite of the fact that the performance of S-parameters and noise figure drastically degrades.

MOSFET linearity performance degradation subject to drain and gate voltage stress

Device parameters degradation of nonlinear elements subject to drain and gate voltage stress is examined experimentally. Analysis of metal-oxide-semiconductor field-effect transistor linearity degradation due to stress is given. Effects on radio frequency (RF) circuit linearity are investigated systematically through a SpectreRF simulation based on measured device data.

Hot Carrier Injection Stress Effect on a 65 nm LNA at 70 GHz

The hot carrier injection stress effect on a 65 nm low-noise amplifier at the 70 GHz range of operation has been studied. The experimental data show that the minimum noise figure increases ( ~2 dB) and the maximum small-signal power gain decreases (~3 dB) after 10 h of HCI overstress due to transconductance degradation as evidenced by 65 nm individual transistor measurement.

Analysis and modeling of LC oscillator reliability

In this paper, MOS device degradations due to hot carrier and gate oxide breakdown are shown experimentally, and their effects on the NMOS LC oscillator have been evaluated analytically and through SpectreRF simulation. The reduction in transconductance of the differential pair transistors may cause the oscillation to cease. The amplitude of oscillation reduces as the equivalent tank resistance decreases due to the breakdown effect on the MOS varactor. The reduction of amplitude reduces the tank capacitances, and therefore shifts the frequency of oscillation and increases the oscillator phase noise. The tank amplitude of the oscillator is derived analytically. A closed-form expression for the average capacitance of the varactor that accounts for large-signal effects is presented. Finally, a set of guidelines to design an LC oscillator in reliability is presented.

Impact of temperature-accelerated voltage stress on PMOS RF performance

The thermal electrochemical analysis and modeling of negative bias temperature instability, oxide breakdown, and hot-carrier injection effects on metal-oxide-semiconductor devices are performed. The temperature-accelerated voltage stress has been examined experimentally. A subcircuit model aiming to evaluate the stress-induced degradation via simulation is developed. The measured and simulated performance for fresh and stressed devices at different temperatures is presented. The radio frequency performance degradation of a test circuit due to temperature-accelerated voltage stress is investigated.

Study of Electrical Stress Effect on SiGe HBT Low-Noise Amplifier Performance by Simulation

This paper investigates the hot-carrier-induced performance degradation in a cascode low-noise amplifier using SiGe heterojunction bipolar transistors. Changes in device characteristics due to accelerated hot-carrier stress are examined experimentally. The vertical bipolar inter-company (VBIC) model parameters extracted from measured device data before and after stress are used in Cadence SpectreRF simulation to evaluate the circuit performance degradation