Patent ID: 7535280

Claim:
An apparatus for shifting a received signal modulated relative to a first reference voltage level to an output signal modulated relative at a second reference voltage level, comprising: a first network and a second network coupled substantially in parallel between an input and an output, the first network including: a resistor coupled to the input; a first transistor having a control electrode coupled to the resistor, and other electrodes coupled between first and second voltage sources; a first current source coupled between the first transistor control electrode and one of the first and second voltage sources; and a second current source coupled between one of the first transistor other electrodes and one of the first and second voltage sources, the second network including: a second transistor having a control electrode coupled to the input, and other electrodes coupled between the first and second voltage sources; a first capacitor coupled between one of the second transistor other electrodes and the first transistor control electrode; a second capacitor coupled between one of the second transistor other electrodes and the output; and a third current source coupled between one of the second transistor other electrodes and one of the first and second voltage sources.