CCDA Line Stage Kits

The Constant-Current-Draw Amplifier (CCDA) is a compound circuit that holds a grounded-cathode amplifier directly cascaded into a cathode follower. So what; what’s so special about this obvious pairing? Its special status lies in the details. Each triode sees the same cathode to plate voltage and the same load resistance and same idle current draw. Each sees the same signal voltage swings. Both grounded-cathode amplifier and the cathode follower are in voltage phase, but not current phase. For example, as the grounded-cathode amplifier sees a positive going input signal, its plate current increases, which increases the voltage developed across the plate resistor, which in turn swings the plate voltage down. This downward voltage swing is then cascaded into the grid of the cathode follower, which decreases the plate current to the same degree that the previous stage's current increased. This results in the constant current draw feature of this topology (a highly desirable feature, as the signal amplification will not alter the amount of current being sourced from the power supply and consequently not perturb the power supply, thus greatly simplifying the design consideration of the power supply).