<p>Many medical, environmental, and industrial control applications rely on wide-dynamic-range sensors and A/D converter systems. For most photo-detector-based applications, the input-current is integrated onto a capacitor, either with a variable time, or a variable capacitor value, followed by a sample-and-hold and a voltage A/D converter. The penalty for achieving wide-dynamic-range with the above approach is power and circuit complexity. </p><p>We propose to use the unique properties of current-input continuous-time Delta-Sigma A/D converters to combine the photo-detector current-integration with simultaneous wide-dynamic-range A/D conversion, using programmable reference currents and programmable clock frequencies. </p><p>A programmable current-input wide-dynamic-range Delta-Sigma A/D converter is designed and fabricated using MOSIS AMI 1.5 um 5 V CMOS process. The programmable A/D converter test results exhibit a consistent 12-bit resolution over the programmability range of the reference-currents, from 17.2 nA to 4.4 uA. The supply-current varies from 60 uA to 240 uA, whereas the A/D converter sample-rates increase from 4 Samples/s to 1 kSamples/s, achieving an overall system-dynamic-range of 20-bits. </p><p>An RF-powered version is designed and fabricated using MOSIS ON 0.5 um 3 V CMOS process. It is designed to work at 128 Samples/s to 11.25 kSamples/s sample-rates, achieving 12-bit resolution with only 128 oversampling ratio. The A/D converter supply-current is designed to range from 10 uA to 70 uA to allow its integration with an RF-power source. The RF-powered version of the programmable Delta-Sigma A/D converter includes an on-chip voltage regulator that generates a stable 3 V DC-voltage, and consumes only 15 uA current.</p> / Dissertation

The project aims to detect rear approaching vehicles for cycslist with a low power consumption. Study focuses on acoustic features of the sound of rear approaching vehicles and examines the useful indicators to detect the vehicles. The project includes more then one correlation and reveals their success rates for as many as samples possible.