INA193: Failing at Induced conducted disturbances

Tool/software:

Hi Team,

We are performing the HF test(Induced conducted disturbances test) ranging 150KHz to 230MHz at 10Vrms. In this test we are using a CLAMP and cables (unshielded) are placed inside it and showering the HF.

We have connected a shunt resistor across the INA+ & INA- of 4.02 Ohms. To protect the inputs from transient events, connected the BI-direction TVS diodes with a series resistor of 100Ohms(MELF).

Also we have 2 current generator loops of 10~10mA connected with a pad of shunt resistor(4Ohms). As per the application the current should lie between 20mA~23mA. 

Also at the inputs choke and filtering Capacitors are connected along with the INA193 O/P RC filter of 1.5K & 1uF.

Issue:

• • • HF injected the current is dropped below 20mA
    • The HF frequency it fails is 100MHz to 230MHz

Help required:

• • Other than mentioned what are the filtering elements of how much can be added
  • Where design lacks in filtering the high frequency noise
  • The bandwidth of INA is 500KHz, why is it still not opposing the HF noise when injected?