The cascomp amplifier is modified to provide a dynamic biasing circuit which varies the bias point of the cascomp amplifier in proportion to the change in the true bias point of the main channel pair to allow full thermal V.sub.be error correction for overdrive conditions and for common-mode signals. A buffer amplifier senses the average voltage of the main channel input transistor emitters and generates a voltage proportional to this average which is added to the biasing network for the cascomp amplifier common-base amplifier transistors.

A differential transconductance amplifier includes two error amplifiers which provide an error correction current which linearizes a main differential amplifier. Two reference transistors coupled to the main differential amplifier provides two sets of input voltages to the two error correction amplifiers. The output currents of the main amplifier and the two error correction amplifiers are summed to produce a linearized output.

This disclosure depicts a substantially constant capacitance circuit for use with an external circuit having a variable voltage signal across first and second terminals. The circuit produces a constant capacitance across the terminals as the voltage signal varies. The value of capacitance is adjustable. The capacitance circuit comprises a first variable voltage source having its positive terminal operatively connected to the first terminal and a second variable voltage source having its positive terminal operatively connected to the second terminal. First, second, third and fourth reverse biased diodes are provided. The first diode is connected across the first voltage source and the fourth diode is connected across the second voltage source. The second diode is connected from one side of the first voltage source to the opposed side of the second voltage source and the third diode is connected between the first and second voltage sources in an opposite configuration to the second diode. The first, second, third and fourth diodes are connected to be reversed biased by the variable voltage signal and by the first and second voltage sources. The substantially constant capacitance circuit provides a substantially constant equivalent capacitance across the first and second terminals of the external circuit as the level of the variable voltage signal changes.

A feed-forward amplifier having delay lines formed as microstrip transmission lines, for reliability and low losses, and signal amplifiers that have phase linearity, to match the delay lines, and a relatively high gain. The resulting device can be manufactured more reliably at relatively low cost, but has improved error cancellation performance, improved temperature stability, and is simple to tune after assembly, without removal of components.

An amplifier that accurately amplifies signals over a wide bandwidth, including DC, has a voltage-to-current converter, a feed-forward resistive element, a buffer, an input resistive element, a feedback resistive element, and an operational amplifier. A first end of the feed-forward resistive element is coupled to an output of the voltage-to-current converter and to an input of the buffer. A first end of the input resistive element is coupled to an input to the voltage-to-current converter. A first end of the feedback resistive element is coupled to an output of the buffer. An inverting input of the operational amplifier is coupled to a second end of the input resistive element and to a second end of the feedback resistive element. A noninverting input of the operational amplifier is coupled to ground, and an output of the operational amplifier is coupled to a second end of the feed-forward resistive element.