L-Band Input RF-MUX 900-2200MHz using SPDT, High ISolation Switch Matrix

Document created by analog-archivist Employee on Feb 23, 2016Last modified by analog-archivist Employee on Aug 10, 2016
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We need to replace HF relays to build a 4-to-1 input RF mux on a satellite
receiver. 4 antenas inputs, levels between -65 and -20dBm, 75Z, directly coming
from LNB. Do very low level. No nood to pass DC, but good isolation and lowest
insertion loss and very low noise floor (betcause of the so low RF levels) are
required. We plan to base that input mux on 3x HMC348 devices. Is it the best
AD device choice for that requirement ? Whould you suggets to use only 2
devices connecting RFC pins close together ? Any comment/suggest/application
schematics that  could help ?
Technical Specifications-
75Z system
Application: Satellite TV for South America
· Insertion Loss <= 0.5dB at 1 GHz, 0.6dB at 2.2GHz
· P1dB no constraints
· Settling time no constraints
· Isolation between 2 inputs (>75dB  at 1 GHz)


The HMC348LP3E could be suitable for this application but it was discontinued
The HMC349ALP4CE is the replacement part recommended. The HMC349ALP4CE offers
high isolation and low insertion loss but it was designed and specified for 50
ohm systems. It will still be functional in the 75ohm systems but the its
performance might be degraded. We can recommend you to evaluate this part in 75
ohm test system for comparing the RF performance in your application.

The HMC8038 is our new high performance SPDT switch planned for RTS in Oct’15
and could be the another candidate for this application. Attached is the
preliminary datasheet for our HMC8038, the engineering samples are currently
available. Again this part was designed and specified for 50 ohm systems so the
customer should evaluate the part to see the performance in the 75 ohm test
system. (3x SPDT will provide in general a better isolation and lower
cross-talk compared to directly going for an SP4T switch)