Why do we need Miller effect?
This effect protects the capacitance of the equivalent circuit. At higher frequencies, the circuit gain can be controlled or reduced by the miller capacitance because handling the inverting voltage amplifier at such frequencies is a complex process.
What is Miller’s theorem of capacitor?
With the help of miller theorem, the capacitance of the equivalent circuit of the inverting voltage amplifier can be increased by placing extra impedance between input and output terminals of the circuit. This effect occurs only in inverting amplifiers.
What kind of transistors are used for cascode?
The cascode circuit can also be built using bipolar transistors, or MOSFETs, or even one FET (or MOSFET) and one BJT. This circuit arrangement was very common in VHF television tuners when they employed vacuum tubes . The cascode arrangement offers high gain, high bandwidth, high slew rate, high stability, and high input impedance.
How does a dual gate cascode work in a VHF receiver?
A dual-gate MOSFET often functions as a “one-transistor” cascode. Common in the front ends of sensitive VHF receivers, a dual-gate MOSFET is operated as a common-source amplifier with the primary gate (usually designated “gate 1” by MOSFET manufacturers) connected to the input and the second gate grounded (bypassed).
How is the cascode configuration represented in a voltage amplifier?
The cascode configuration can be represented as a simple voltage amplifier (or more accurately, as a g-parameter two-port network) by using its input impedance, output impedance, and voltage gain.
How is the wide bandwidth of the cascode configuration explained?
The key to understanding the wide bandwidth of the cascode configuration is the Miller effect. The Miller effect is the multiplication of the bandwidth robbing collector-base capacitance by voltage gain A v. This C-B capacitance is smaller than the E-B capacitance. Thus, one would think that the C-B capacitance would have little effect.