Patent ID: 8552788

Claim:
An apparatus, comprising: a level shifter having a first input, a second input, a first output, and a second output, the first and second inputs configured to receive a differential input voltage signal and the first and second outputs configured to provide a differential output voltage signal, the level shifter comprising: a plurality of capacitors comprising a first capacitor and a second capacitor; a plurality of switches electrically coupled to the plurality of capacitors, wherein the level shifter is configured to control the electrical connectivity of the plurality of capacitors via the plurality of switches over at least a first phase, a second phase, a third phase, and a fourth phase; and a charger block configured to charge the first and second capacitors during at least a portion of the third and fourth phases to a shift voltage about equal to a difference in voltage between a common-mode voltage level of the differential input voltage signal and a reference voltage; wherein the plurality of switches are configured to electrically connect the first capacitor between the first input and first output during the first phase and between the second input and the second output during the second phase, and wherein the plurality of switches are further configured to electrically connect the second capacitor between the second input and second output during the first phase and between the first input and the first output during the second phase, wherein the level shifter is configured to control a common-mode voltage level of the first and second outputs to be about equal to the reference voltage, and wherein the level shifter is configured to control a voltage difference between the first and second outputs to be about equal to a voltage difference between the first and second inputs.