Methods and apparatus are described for generating or amplifying a differential signal. The output of a first op amp corresponds to one end of the differential signal. The output of a second op amp corresponds to the other end of the differential signal. The inverting input of the first op amp is coupled...http://www.google.se/patents/US6566946?utm_source=gb-gplus-sharePatent US6566946 - Noise reduction scheme for operational amplifiers
