power splitter as a attenuator

Hi,
Power splitter QCN-34 along with the pin attenuator ( QCN-34 from minicircuits) used as a variable attenuator in one of the RF Transmitter section, can any one describe application power splitter in variable attenuator ckt.

Regards
roshni

Kind of a crude way to do it. Where does all the reflected power go in that circuit? It bounces around and causes peaks and nulls that mean your insertion loss vs. frequency will not be very flat.

A better way would be to use two 90 degree "power splitters", 50 ohm loads on the isolation ports, and two pin diodes in shunt. That way reflected power ends up in the 50 ohm loads instead of bouncing around.

Added after 3 hours 8 minutes:

Like this variable attenuator:

thanks biff4......i will try to implement as per ur suggestion.

sometimes the hybrid couplers you use have a thru DC connecton. If that is true in your case, you could put the bias connections on the outside of the couplers, instead of physically right at the PIN diodes. Gives a little better performance, as the bias line parasitics are less important along the input or output 50 ohm lines.