Signal-level compensation for communications circuits

A signal-level shifter comprising:

• a voltage-follower stage including a voltage-follower input for receiving an input signal, a voltage-follower output, and a voltage-follower stage transistor coupled between the voltage-follower input and the voltage-follower output for providing an output signal at the voltage-follower output responsive to the input signal;
• an output stage coupled to the voltage-follower stage and including an output stage transistor for shifting a signal level of the output signal;
• a sensor for sensing variations in at least one of characteristics of the transistors and a voltage of a power supply powering the signal-level shifter and providing a control signal indicative of the variations
• an output signal compensator coupled to the voltage-follower output for providing a compensator signal responsive to the control signal for reducing the impact of the variations on the output signal.

A method of compensating for signal-level variations in communications circuits, comprising the steps of

• providing a voltage-follower including a signal input for receiving an input signal, a signal output, and at least one transistor coupled between the signal input and the signal output for providing an output signal at the signal output responsive to the input signal;
• sensing variations in at least one of characteristics of the transistor and a voltage of a power supply powering the voltage-follower and providing a control signal indicative of the variations;
• and
• adding a compensating signal to the output signal, the compensating signal being responsive to the control signal and having a phase opposite to the variations.