cascode transistor

ian field

Joined Oct 27, 2012
why the cascode transistor has high output impedance. can any one provide better resource for its mathematical verification?
High res CRT monitors used a casc-ode video amplifier for its excellent frequency response - but its high output impedance wasn't so good for driving the CRT cathode capacitance. The better manufacturers followed it up with a complementary pair emitter follower buffer.

In high end monitors, there could be transistors rated over 1GHz, about 600MHz was more or less typical.

You can work out the actual dot clock frequencies from the resolution charts.