90 degree hybrid

[greebling]

How does a 90 degree hybrid work?

 

[buding]

splits the signal, and output signals are shifted in phase with 90 degrees.

Buding

 

[greebling]

how is the 90 degree phase shift achieved?

 

[davston]

It depends on the frequency.

At higher frequencies where the wavelength is suitably small the 90 degrees shift can be achieved by a length of transmission line.

At lower frequencies where the parasitics of components do not have such an effect you can acieve a 90 degree difference in the two outputs using inductors and capacitors. For example a series inductor and shunt capacitor in one arm with a shunt inductor and series capacitor in the other.

I generally find that at frequencies over 2GHz standard surface mount components (0402) are starting to cause problems in hybrids mainly due to the tollerances.

David.

 

[joni]

another important thing is isolations between output signals ( in microwave band better than 20dB )