A number of field effect transistor circuits include voltage controlled attenuators or voltage controlled processing circuits. Example circuits include modulators, lower distortion variable voltage controlled resistors, sine wave to triangle wave converters, and or servo controlled biasing circuits.
Where W=width and L=channel length of the enhancement mode device.
k′=a constant based on the manufacturing process of the enhancement mode device and where Vds=voltage across the drain and source, and where Vth=threshold voltage, and where Vgs=gate to source voltage.