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what is application of cascode amplifier's high output impedance?

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ermai

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In general , amplifier has low output impedance for loading,but cascode has high.
Cascode amplifier behaves as a transconductance amplifier.
Does cascode amplifier output as a current source to drive a load?
If it does,what kind of equipment(or device) is load to cascode amplifier?
Thanks.
 

The high output impedance of a cascode allows us to make amplifiers with a very high voltage gain, but only if the load impedance on the output is also very high. For example, in a multi-stage amplifier, the output of a cascode gain stage could be connected to the input of a FET gain stage.

Another advantage of cascodes is that they eliminate Miller effect, so you can get better bandwidth than with a non-cascode gain stage.
 

In general , amplifier has low output impedance for loading.
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In general, the assumption is wrong.

Cascode amplifier is a transistor level structure. I'm not aware of an elementary amplifier structure, that has both voltage gain and low output impedance. Voltage gain is mostly generated by connecting a medium or high load impedance to an amplifier transistor or a cascode structure. The amplified signal is then possibly buffered to expose a load output impedance.
 

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