23CM 500mW Amplifier AH101 - duplicated with revised matching

Since I have a lot of these boards I used one to make a test fixture. OSL calibration of the VNA right at the device legs proved feasible since I have some 50ohm RF chip resistors. Fortunately, the measured S parameters were broadly consistent with the tabulated S parameters in the datasheet.

With the device soldered onto hte board I switched between the calibration at the device legs and the calibration at the SMA sockets. This allowed me to infer the electrical length and impedance of the connecting micro-strips, and any strays.The length and impedance were close to the expected value so I was able to confidently rework the matching. 

As you can see below I was able to use a single inductor at the SMA end of the board for the input. I inferred that a microstrip with slightly higher impedance would give a better match. The crazy cutter went mad and the result was just a few dB improvement to a return loss of 21dB. I overshot the mark!

Matching for the output network was placed at the device end of the output microstrip. The capacitor to ground was meant ot be 1.5pF, but I found the slightly smaller 1pF capacitor gave me a better result. Return loss of 24dB was achieved.

That makes two successful amplifier boards and a great learning exercise. I am a lot more confident with the Smith Chart now and RFSim99.  I still have a heap of the AH101 devices so one day I would like to try 4 in parallel using Wilkinson dividers.

 

 

That might have been the end of the matter but I noticed the claimed specifications in the datasheet were not supported by the S parameters. Which should be embarrassing to a manufacturer!

To be fair, this is a discontinued part and the original manufacturer has changed hands several time. So let's look at the TQP7M9102. This is Qorvo's suggested replacement. What we find is a table of S parameters in the datasheet explicitly qualified by: 

"Test Conditions: V CC  = +5 V, I CQ  = 135 mA, Temp. = +25 °C, unmatched 50 Ohm system, reference plane at device leads"

The S parameter file downloaded states:

"The data is for the unmatched device in a 50 Ohm system, 2-port file de-embedded to the device leads."

So my expectation is this should be the same dataset. The best I can say is they are broadly similar. I drew this to Qorvo's attention. The response simply acknowledged the error. With that attitude I can no longer consider Qorvo for commercial applications which means it is unlikely any of their products will ever find a way into my ham projects. Once those AH101's are gone that's it!

 

73's