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Query about AD8309's Output of Limiting Amp

Question asked by WayneQ on Jan 30, 2014
Latest reply on Jan 30, 2014 by jdobler

Hi, there


I have a query about AD8309's output of limiting amplifier.


We feeding 2 signals at 70.6Mhz with a amplitude difference of 4dB to the device and  observed that 
amplitude difference 8dB at the output of limiting amplifier device.

Input signal to Limiting amplifier is at frequency 70.6Mhz

Two signals at 70.6Mhz generated from 2 different signal generator and combined  using a combiner.
The amplitude of one signal at -80dBm and another signal at -76dBm.

The limiting amplifier output is connected to spectrum analyzer (Center frequency 70.6Mhz ;span 10Mhz,RBW and VBW of 3MHz).

My schematic refers to the AD evaluation board schematics.

Can we suggest any method to improve this amplitude difference at the output limiting amplifier to 12dB?

If it inherent property of this part then you have any limiting amplifier which reproduce amplitude difference of more than 12dB
at the output for the 2 input signal at 70.6Mhz with amplitude difference of  4dB.

Thanks in advance for your kindly help!