Fully differential operational amplifiers using CMOS compatible lateral bipolar transistors with improved common-mode regulation

A new bias circuit for a CMOS compatible lateral bipolar transistor differential pair is presented. The circuit compensates for all process and bias dependent variations of the lateral collector current to emitter current ratio alpha . Experimental results show that its application to a fully differential amplifier improves the precision of the common-mode output voltage regulation by at least an order of magnitude.