Noise Generated and Maximum Amount of Voltage/Current that can go back into Amplifier

Hi Andrew2277,

NF was not measured on the HMC1087. I would expect NF to be around 6-8 dB.

Typically, we expect ADI amplifier to survive a 7:1 VSWR condition. under such conditions roughly 56.25% of the transmitted power is reflected back into the device, or roughly 5 watts.

Are you looking for MTTF data under VSWR/reflected power conditions? 

Regards,

Jim B

Yes, MTTF data based off of the VSWR/Reflected Maximum Power Conditions allowed. Thanks in advance for the response!

Hi Andrew,

                    I'm not sure that can be done as MTTF is based on reliability data under normal operating conditions. VSWR/reflected power is not part of qualification testing.

Okay, then any MTTF data that can be provided based off of testing under nominal operating conditions. I understand that this can change especially dependent on how the device is operated I.E. pulsed or CW application, but I was just looking for some MTTF from the manufacturer to come up with some type of estimation/approximation for it. Thank you.

Start with the reliability report for the device or the process. That will give you a nominal MTTF which usually assumes operating the device at its lifetime at a die temperature of 85 degC. If you operate at a lower or higher temperature than this, the deivces's expected MTTF will change and there are equations that you can use to recalculate the MTTF. I don't think that it's meaningful to think about how poor return loss can affect this calculation. That would assume that the poor return loss is present for the lifetime of the device. You could do this. Figure out how much extra power is being consumed in the devie because of the RF power reflecting back into the the device. That is going to give oyu a higher operating die temperature (Die Temp = (Power Consumed x Thermal Resistance) + Tcase. If you calculate out that temperature, you can recalculate the MTTF. - Eamon 

Hi Andrew2277,

                                Attached is the qualification report for the HMC1087. MTTF is on the last page of the report.

Regards,

Jim B

PDF

Thanks Jim, this report helps out a lot to go back with some of the answers to questions that I needed for my task; I am trying to see the best/accurate way to measure the Noise Figure off of the Evaluation Board since that data was not included, and then just to follow up on my initial question regarding the VSWR and how much reflected power the device could have, I am going to word my question slightly differently. What would the maximum amount of allowable RF Power incident on the Transmitting Amplifiers (This being the HMC1087F10) from the device under testing? I feel as if this would still be the roughly 5 Watts value, but just wanted to ask the question with some more precise wording in case that was unclear in the beginning. Thanks in advance for all of the help!

Hi Andrew 227,

                               With a 7:1 VSWR, the fault condition we expect the amplifier to survive, I would expect 5W to be reflected back into the device when operating at PSAT. 

You can use a noise figure meter if you have one, A PNA-X with a NF measurement capability, or, a spectrum analyzer.  The link below details the process to use a spectrum analyzer to measure noise figure.

Can I measure noise figure with a spectrum analyzer, a preamp and a signal generator? - Technical Support Knowledge Center Open

Regards,

Jim B