An analog to digital signal converter includes an integrator and a sample and hold circuit. Precisely repeatable timing signals for both the integrator and sample and hold circuit are provided by a microprocessor. The device provides low pass filtering without the phase lag normally associated with linear...http://www.google.com.tw/patents/US5172117?utm_source=gb-gplus-share專利 US5172117 - Analog to digital conversion using an integrater and a sample and hold circuit
