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LTC5596 Oscillation:

Category: Hardware
Product Number: LTC5596

I am seeing a 7.6 MHz oscillation at the detector output when saturating the input of the LTC5596 detector. I have a 15 dB directional coupler providing the input to the detector at the output of a MMIC die. I have no load capacitance and can quiet the oscillation by using < 200 ohms at the detector output. The detector looks like it should be able to operate up to an open circuit. Has anyone seen these oscillate?  In some cases it causes a latching effect in the detector so that the input level has to drop a few dB before the oscillation stops and the detector behaves again.

  • Hi RDD,

    My understanding is the LTC5596 output stage is well buffered internally. I'd suggest making sure the power pin at the LTC5596 has the typical smaller- and larger-valued power supply bypass capacitors.  

    Also check the LTC5596 power and ground pin voltages with the same scope, on a different trace, to make sure the voltages there are stable throughout the oscillations you see on the output. This means checking for good, low-inductance ground plane also.