A gain cell circuit is disclosed having an outer pair of common base transistors and an inner pair of common emitter transistors. External base resistors and emitter resistors are added to the common base transistors for controlling the zero formed by the internal capacitance of the common base transistors, thereby cancelling the dominant pole formed by the common emitter transistors and providing compensation and improvement in gain cell bandwidth.
Dc-Coupled Schmitt Trigger Circuit With Input Impedance Peaking For Increasing Switching Speed
A compact, DC-coupled Schmitt trigger circuit is disclosed for providing fast switching in response to differential current signals from an input source such as an amplifier. The circuit includes first and second matched pairs of transistors disposed for performing switching and feedback functions, respectively, and for producing a voltage at an input or base of the first pair equal to the sum (AND function) of the source voltage and the voltage at an emitter of the feedback pair. In response to the applied current signals, the transistors of the second matched pair are always in a conducting state (and requires no extra time to turn on) regardless of the conducting state of either of the transistors of the first matched pair. The circuit includes first and second matched pairs of resistors coupled to selected ones of the transistors, the resistance values of which second matched pair of resistors are selected such that the input impedance of the circuit peaks at a selected high frequency of the applied current signal.