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Effect of PSU noise on ADL5375 Modulator

Question asked by JGerber on Jul 19, 2013
Latest reply on Jul 29, 2013 by THA

Hi there,

We are using the ADL5375 (and ADL5380) devices in a direct conversion transmitter + receiver.

We have run into micro-phonic / pizo-electric problems on both Tx and Rx. After finding some high value X7R caps

on our sensitive supply lines on the synthesizer and replacing with tantalums, the problem was very much reduced. But not gone.

How well are the supply lines of the ADL5375 isolated from the RF components? We have 100pF and 100nF caps on the supply

lines (mixed NPO and X7R) plus one 4u7F X7R. Would a pizo-eletric spike (microvolts?) from the 4u7F modulate

the output signal of the ADL5375 (or ADL5380)?