Driving amplifier circuit with digital control and DC offset equalization

A driving amplifier circuit comprising:

• a first driver for sourcing a load current to a load;
• a second driver for sinking the load current from the load;
• a first operational amplifier (op-amp) coupled to an input signal for driving the first driver;
• a second operational amplifier coupled to the input signal for driving the second driver;
• a first bias circuit for biasing the first driver;
• a second bias circuit for biasing the second driver;
• an enabling circuit, coupled to the first bias circuit and the second bias circuit, for enabling either the first bias circuit or the second bias circuit according to a control signal;
• a digital control circuit, coupled to the enabling circuit, for monitoring currents of the first driver and the second driver to generate the control signal;
• and
• an external circuit, coupled to the inverting inputs of the first operational amplifier and the second operational amplifier, for adjusting DC offset of at least one of the first operational amplifier and the second operational amplifier so that the first op-amp and second op-amp have equal DC offset, the external circuit comprising:
• at least a tapped variable resistor coupled to a reference voltage, wherein when the tapped variable resistor is selectively tapped in different places, a DC voltage at the first operational amplifier will be different from a DC voltage at the second operational amplifier.