The design of active resistors and transductors in a CMOS technology

Merged with duplicate record 10026.1/2618 on 07.20.2017 by CS (TIS)This thesis surveys linearisation techniques for implementing monolithic MOS active resistors and transconductors, and investigates the design of linear tunable resistors and transconductors. Improving linearity and tunability in the presence of non-ideal factors such as bulk modulation, mobility-degradation effects and mismatch of transistors is a principal objective. A family of new non-saturation-mode resistors and two novel saturation-mode transconductors are developed. Where possible, approximate analytical expressions are derived to explain the principles of operation. Performance comparisons of the new structures are made with other well-known circuits and their relative advantages and disadvantages evaluated. Experimental and simulation results are presented which validate the proposed linearisation techniques. It is shown that the proposed family of resistors offers improved linearity whilst the transconductors combine extended tunability with low distortion. Continuous-time filter examples are given to demonstrate the potential of these circuits for application in analogue signal-processing tasks.GEC Plessey Semiconductors, Plymout

Universal Voltage Rate Sensor Interface

Measurement of heat flux is required in many aerospace and heat treatment applications. Temperature data collected at embedded sites are noisy especially when measurements are taken in hostile environments. The predicted heat flux, when based on the rate of change of temperature, is more accurate than using temperature data as the latter data form is ill-posed. In the context of heat flux prediction, calculating the rate of change of temperature involves differentiation, which is the primary source of ill-posed effects. This work involves developing a universal voltage rate sensor interface that minimizes these effects and also improves the signal-to-noise ratio. This is based on the concept of amplitude modulating the temperature data and differentiating it at a higher frequency. The proposed concept of improvement in signal-to-noise ratio was verified by the Matlab and PSpice simulations. The experimental outputs matched the simulations results

CMOS systems and circuits for sub-degree per hour MEMS gyroscopes

The objective of our research is to develop system architectures and CMOS circuits that interface with high-Q silicon microgyroscopes to implement navigation-grade angular rate sensors. The MEMS sensor used in this work is an in-plane bulk-micromachined mode-matched tuning fork gyroscope (M² – TFG ), fabricated on silicon-on-insulator substrate. The use of CMOS transimpedance amplifiers (TIA) as front-ends in high-Q MEMS resonant sensors is explored. A T-network TIA is proposed as the front-end for resonant capacitive detection. The T-TIA provides on-chip transimpedance gains of 25MΩ, has a measured capacitive resolution of 0.02aF /√Hz at 15kHz, a dynamic range of 104dB in a bandwidth of 10Hz and consumes 400μW of power. A second contribution is the development of an automated scheme to adaptively bias the mechanical structure, such that the sensor is operated in the mode-matched condition. Mode-matching leverages the inherently high quality factors of the microgyroscope, resulting in significant improvement in the Brownian noise floor, electronic noise, sensitivity and bias drift of the microsensor. We developed a novel architecture that utilizes the often ignored residual quadrature error in a gyroscope to achieve and maintain perfect mode-matching (i.e.0Hz split between the drive and sense mode frequencies), as well as electronically control the sensor bandwidth. A CMOS implementation is developed that allows mode-matching of the drive and sense frequencies of a gyroscope at a fraction of the time taken by current state of-the-art techniques. Further, this mode-matching technique allows for maintaining a controlled separation between the drive and sense resonant frequencies, providing a means of increasing sensor bandwidth and dynamic range. The mode-matching CMOS IC, implemented in a 0.5μm 2P3M process, and control algorithm have been interfaced with a 60μm thick M2−TFG to implement an angular rate sensor with bias drift as low as 0.1°/hr ℃ the lowest recorded to date for a silicon MEMS gyro.Ph.D.Committee Chair: Farrokh Ayazi; Committee Member: Jennifer Michaels; Committee Member: Levent Degertekin; Committee Member: Paul Hasler; Committee Member: W. Marshall Leac

Non-invasive blood pressure estimation based on electro/phonocardiogram

Ingeniero (a) ElectrónicoPregrad