Voltage signals have an upper limit and a lower limit and a voltage swing therebetween. Circuits may be designed to work with high or low voltages, may be designed for high or low swings, may be designed to work near a saturation region or in the saturation region. The lower the swing the faster that processing can occur. Often the swing of a signal is sufficient but the upper or lower parameters of the signals need to be adjusted. For example, the signal may need to be shifted up or down so that a transistor receiving the signal operates in the saturation region. Shifting a signal entails maintaining the swing (absolute voltage drop) of the signal while moving upper and lower limits of the signal.
Devices for shifting the current may be complex or may be based on current drawn by a load connected to the shifting device. Relying of the current drawn by the load requires excess power consumption. If the load is modified then the current drawn may be modified and the voltage shift may change accordingly.