LMH6703: 500MHz noise at output when there is no input even after using the recommended RF value

Ooi Zhu Oon

Part Number: LMH6703

Hi,

I am using LM6703MA as a unity gain amplifier and gain=0.8V but I observed a 500MHz oscillation noise with 500mV Vp-p at the output even after I got a 50ohm termination the input. I am using recommended RF = 390ohm. Is the noise expected? If not please advise.

Thanks.

Regards,

Isaac

over 1 year ago

0 Ignacio Vazquez Lam1 over 1 year ago

TI__Genius 11000 points

Hi Isaac,

This should definitely not be occurring. Could you please attach a circuit file or schematic for us to get a better idea of what you're seeing? This will be very helpful in debugging the errors you are getting.

Best Regards,

Ignacio

0 Ooi Zhu Oon over 1 year ago in reply to Ignacio Vazquez Lam1

Prodigy 50 points

Hi Ignacio,

Please see the below some of the configuration that I had tried while debugging. I still observed the same 500MHz oscillation in all the configuration below.

Thanks.

Regards,

Isaac

0 Michael Steffes over 1 year ago in reply to Ooi Zhu Oon

Guru 48395 points

you might try putting a 20ohm to ground on the V+ input, sometimes there is self oscillation in the input stage that will fix. Also, do not probe right on theoutput pin, probe through a 50ohm R.

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LMH6703: 500MHz noise at output when there is no input even after using the recommended RF value