Signal specific electric potential sensors for operation in noisy environments

Limitations on the performance of electric potential sensors are due to saturation caused by environmental electromagnetic noise. The work described involves tailoring the response of the sensors to reject the main components of the noise, thereby enhancing both the effective dynamic range and signal to noise. We show that by using real-time analogue signal processing it is possible to detect a human heartbeat at a distance of 40 cm from the front of a subject in an unshielded laboratory. This result has significant implications both for security sensing and biometric measurements in addition to the more obvious safety related applications

Switched-Capacitor Programmable Sallen and Key Lowpass Filters

This thesis deals with a different approach to switched-capacitor filters than previously seen by the use of a Sallen and Key topology. It is shown that a Sallen and Key second-order topology approach to a switched-capacitor filter gives reasonable filter performance results, contrary to what the literature leads one to expect. It is also shown that the Sallen and Key second-order topology with modification to a third-order section with buffers results in a high performance switched-capacitor filter with fewer components than previous switched-capacitor filters. This results in fewer monolithic chip size requirements, reduced power requirements, and less cost. Higher order filters could be obtained by cascading either one of the second- or third-order switched-capacitor sections together. Desired filter Q values and cutoff frequencies are shown to be obtained by changing the capacitor ratios and clock frequencies, respectively

A programmable switched capacitor filter for audio applications

114 p.Switched capacitor technique [1] is a well-developed technique for integrated filter design. It plays a critical role in integrated filters and mixed-signal circuit design. Well known of its advantages such as good accuracy and less external components required over its continuous-time counterpart, it is becoming increasingly popular in commercial application. With the advance in CMOS process, the possibility to achieve high accuracy capacitors makes switched capacitor filter's performance more reliable.MASTER OF ENGINEERING (EEE

An implementation of memory-based on-chip analogue test signal generation

ISBN: 0780376595This paper presents a memory-based on-chip analogue test signal generation approach that is suitable for the test of an analogue and mixed-signal (AMS) core. This core contains programmable electronic interfaces for acoustic and ultrasound transducers. The test signals that must be generated on-chip have only low or moderate frequencies (10 Hz-10 MHz). The test circuitry designed in a 0.18 mu m CMOS technology includes a programmable shift-register, a clock divider, and a programmable switched-capacitor filter bank. By controlling the shift-register length and the sampling frequency, the paper shows that high quality single tone signals can be generated on chip in the band of interest