A digitizer for a barcode scanner includes an amplifier and a comparator. The amplifier receives a feedback signal and a differentiated return signal on a first port, and a reference voltage signal on a second port. Based on a difference between voltages on the first and second ports, the amplifier outputs...http://www.google.com.au/patents/US5864129?utm_source=gb-gplus-sharePatent US5864129 - Bar code digitizer including a voltage comparator
