Wideband class ab crt cathode driver

Abstract

A wideband amplifier is configured to allow sophisticated low voltage signal processing in a low-cost, high frequency integrated circuit driver. The integrated circuit driver provides output currents to drive high voltage discrete power transistors in such a way as to achieve maximum frequency response from the low-cost discrete transistors. The discrete power transistors in turn provide an output voltage suitable for driving, for example, a CRT display. The transconductance amplifiers, video processing circuitry, current multipliers, and summers are formed in an integrated circuit device utilizing readily available processing and circuit design techniques, and a relatively small number of discrete low power components, including pull-up and pull-down transistors which are chosen to have a fairly high frequency of unity current gain (F.sub.t), yet which are readily available at a very low cost. In order to utilize such low cost pull-up and pull-down transistors, these transistors are driven either in cascode or in a unity gain current mirror configuration from separate pull-up and pull-down currents, in order to avoid the deleterious effects the input base capacitance of the transistor has on its frequency response.