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ADL5530 Output Range vs Absolute Maximum ratings

Question asked by jnewell on Apr 29, 2015
Latest reply on May 1, 2015 by bkamak

Using the ADL5530 as a buffer/amplifier between the ADF4360 and a stub antenna. Nominal frequency range 118 to 137MHz.

Several ADL5530device have died - just not amplifying. Typical of open circuit collector(?)

The ADF4360 can output 0dBm with a Lattice balun at the input to the 5530. The 5530 output goes through a single section PI LPfilter with a 150MHz 3dB point. This is then connected to a stub antenna, nominally 50ohm at 127MHz.

Assuming the 5530 outputs +16dBm, this is 40mW, which into 50ohm is 1.4V rms 2V positive peak. Added to a 5V supply rail, does this mean the +6V maximum Vsupply is exceeded?

Actually, I operate at 3.3V, and I measure 3V-p-p, so I actually only get to 4.8V, which is within spec. But in the field it is possible that the antenna can also receive radiated transmissions from nearby transmitters, and so could exceed the 6V limit.

 

Is this why the devices are failing? I have several solutions if this is the case, but would appreciate an input from someone who is familiar with the internals of this device

John Newell

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