Certain applications in electronics require that the upper or lower extremity of a wave be fixed at a specific value. In such applications, a clamping (or clamper) circuit is used. A clamping circuit clamps or restrains either the upper or lower extremity of a waveform to a fixed DC potential. This circuit is also known as a direct-current restorer or a base-line stabilizer. Such circuits are frequently used in test and measure equipment. Depending upon the equipment, you could find negative or positive clampers with or without bias. The figure below, views A through E, illustrates some examples of waveforms created by clampers. However, before we discuss clampers, we will review some relevant points about series RC circuits.