The output return loss may burn the PA by the worse VSWR of the PA output-Load, so what's the worst VSWR value which is acceptable to the PA(like HMC907)?
Hi seven wang,
The HMC907 does not have an Absolute Maximum Rating (AMR) for output VSWR. The HMC797 is a similar part, fabricated on the same PHEMT-H process, and it specifies a Pout AMR of +29 dBm into a VSWR>7:1. The same Pout/VSWR rating was targeted for the HMC907, though a rating does not appear on the data sheet and we don’t have data to support such a rating. I would thus suggest that you should limit the RF Pout to a maximum of +29 dBm when the output VSWR conditions could exceed 7:1.
Some VSWR-related concepts worth keeping in mind are as follows:- Decreasing the Pout should allow the part to safely tolerate higher output VSWR.- Decreasing the output VSWR should allow the part to safely tolerate higher RF Pout.- The two modes by which output VSWR related failure can usually be induced are 1) voltage breakdown (in this case where the RF output and Vdd are the same pin, that’s the Drain Bias Voltage AMR) and 2) excessive power dissipation.
-For reliable operation always make sure that your output VSWR and Pout conditions do not cause you to violate the other AMRs (e.g., Channel Temperature, etc.)
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