Cathode followers and feedback amplifiers with high-capacitance loads

Investigation, both theoretically and experimentally, was made into the mode of operation of cathode followers and feedback amplifiers with high-capacitance loads. The capacitance loaded cathode follower compares unfavorably with the resistance loaded cathode follower, particularly regarding operation with fluctuating input signals. Input overdrive of a capacitance loaded cathode follower causes production of transient voltages in the output circuit. Threshold of input overdrive is considerably lower than in resistance loaded cathode followers, especially at high audio frequencies. Also, harmonic distortion is increased at high frequencies and high-frequency response drops off. Experimental analysis of the voltage relations between the input and output circuits was made, and guides for design were developed. It was found that a symmetrical Eg-Ipcurve is the most important factor in development of a cathode follower for driving high-capacitance loads where transient distortion is to be avoided.