An AC coupling circuit is provided that has a level shifter circuit having a p input voltage and an n input voltage and producing a p output voltage and a p output voltage. There is a common mode voltage adjustment feedback circuit configured to cause a common mode voltage output to tend towards a specified reference voltage, the common mode voltage output being an average of the p output and n output voltages of the level shifter circuit. In combination, the level shifter circuit and the feedback circuit allow the interconnection of a first circuit that operates at a first, unspecified, common mode voltage to be connected to a second circuit having a required common mode voltage. The level shifter may be formed of adjustable components such that the frequency response of the level shifter circuit can be adjusted to compensate for a frequency response of an interconnect between the first circuit and the second circuit.