Cascode
The cascode is a two-stage amplifier that consists of a common-emitter stage feeding into a common-base stage. [1] [2] Compared to a single amplifier stage, this combination may have one or more of the following characteristics: higher input–output isolation, higher input impedance, high output impedance, higher bandwidth. In modern circuits, the cascode is often constructed from two transistors (BJTs or FETs), with one operating as a common emitter or common source and the other as a common base or common gate. The cascode improves input–output isolation (reduces reverse transmission), as there is no direct coupling from the output to input. This eliminates the Miller effect and thus contributes to a much higher bandwidth. Contents 1 History 2 Operation 2.1 Stability 2.2 Biasing 2.3 Advantages 2.4 Disadvantages 2.5 Dual-gate version 2.6 Mixer in superheterodyne receivers 3 Other applications 4 Two-port parameters 4.1 BJT casc...