I am drawing a cascode amplifier layout in ADS and i use a sot343 transistor with 4 pins. I need to connect the emitter of above transistor to the collector of the down transistor. Do i have to connect both emitter pins?? They are diagonally and it is not possible.
It should be possible with a diagonal trace, but not so important for the cascode transistor due to the higher emitter driving impedance. A certain bandwidth reduction may be observed though (output capacitance + emitter inductance create a pole).
It will work OK.
Check that the casocde is stable, I've found that these high ft devices are prone to oscillating if there is too much inductance in the emitter or base circuit
If i want to put emitter degeneration at the down transistor will it be the same if i put it only to one of the emitter pins or is it better to degenerate both pins?
I'd keep it symetrical, the floating pad may be small and not have no noticeable effect at your operating frequency, but these devices have still have gain above 10GHz and up there the open pad could cause you stability problems.