Question

What is the difference between cascade and cascode amplifier?

Answer 1

Hint:An amplifier is a type of electrical device that boosts the strength of a signal (a time-varying voltage or current). It's a two-port electrical circuit that uses power from a power source to boost the amplitude of a signal supplied to its input terminals, resulting in a signal with a proportionately higher amplitude at the output. The gain of an amplifier is defined as the ratio of output voltage, current, or power to input voltage, current, or power. A circuit with a power gain higher than one is known as an amplifier.

Complete answer:
Because the performance of a single-stage amplifier is typically insufficient for many applications, several stages can be joined to produce a multistage amplifier. These stages are linked in a cascade, so the first stage's output is connected to the second stage's input, and the second stage's output is connected to the third stage's input, and so on.In a daisy chain, a cascade amplifier is a two-port network with amplifiers connected in series, with each amplifier transmitting its output to the second amplifier's input.

The non-perfect coupling between two stages due to loading is an issue when evaluating the gain of a cascaded stage. The following circuit depicts the two phases of cascaded CE (common-emitter). The voltage divider may be created here by using the first and second stage's input and output resistances. Individual stages alone cannot account for the whole benefit.

A cascode amplifier is a two-stage circuit with a transconductance amplifier and a buffer amplifier in the first stage. The phrase "cascade to cathode" gave rise to the term "cascode." This circuit has several advantages over a single stage amplifier, such as greater input output isolation, better gain, increased bandwidth, higher input impedance, higher output impedance, improved stability, and higher slew rate, to name a few.

The decrease of the Miller effect is the cause for the increased bandwidth. FET or BJT transistors are commonly used in cascode amplifiers. The common source/common emitter mode will be used on one stage, while the common base/common emitter mode will be used on the other.

The transistors in cascade amplifiers are connected in series, but in cascode amplifiers they are connected in parallel. Transistors in cascode amplifiers are linked in parallel. The transistors of a cascade amplifier are linked in a chain, with the output of the first transistor serving as the input for the second transistor. The transistors in a cascode amplifier are stacked one on top of the other.

Note: The non-ideal coupling between stages owing to loading complicates estimating the gain of cascaded stages. Two typical emitter levels are depicted in cascades.The overall gain is not the product of the individual (separated) stages since the second stage's input resistance forms a voltage divider with the first stage's output resistance.