Hello PNA-X'ers,

I am having a bad PNA-X day.

How do I calculate the power sweep range available on my PNA-X.

Is it:

Pmax=Max leveled output power - source attenuation

Pmin=Pmax-power sweep range

Example: from data sheet

Max leveled power = 8 dBm (spec)

Power sweep range 37 dB (spec)

Hence with 20 dB source attenuation, I would be able to achieve:

Pmax=-12 dBm

Pmin=-49 dBm

Or am I missing something?

Thank you

Andy

I am having a bad PNA-X day.

How do I calculate the power sweep range available on my PNA-X.

Is it:

Pmax=Max leveled output power - source attenuation

Pmin=Pmax-power sweep range

Example: from data sheet

Max leveled power = 8 dBm (spec)

Power sweep range 37 dB (spec)

Hence with 20 dB source attenuation, I would be able to achieve:

Pmax=-12 dBm

Pmin=-49 dBm

Or am I missing something?

Thank you

Andy

Just so I am clear (apologies for being a stickler, I just want to make sure I understand correctly):

Min power @ 0 dB source atten is always -30 dBm

So with 10 dB source attenuation,

Min power @ 10 dB source atten is -40 dBm

(Assuming no additional losses).

- is this correct i.e. source power vernier can drop you 30 dB and raise you X dB?

If Max power=spec'd max leveled power - source atten, then why do you spec a power sweep range in the data sheet (since min power fixed at -30 dB below nominal atten value and max leveled power is already spec'd)?

Thanks for all your help,

Andy

The actual minimum power may be as high as -27 dB (at 10 MHz) but over that range the max power is higher than +8. So, you have to look at the frequency range where you are using the box to determine the max power. Different frequencies have different max powers, and the power sweep range will be a minimum of 37 dB, but the min powe will vary as the max power varies as well.

In practice, above about 20MHz, the min power in ALC mode is always less than -30 dBm (at very low frequencies the power range is limited by the low freq performance of the ALC loop). Also, the power range is affected below 3.2 GHz depending if you are in high power mode or not. And, at higher frequencies, the power range is limited by the ALC detector sensitivity, so if you go to open loop mode, you can typically get 60 dB range above about 100 MHz or so.

Maybe I should not have asked the last question, as it has muddied my waters....

Fundamentally, my question is how to interpret the data sheet specs.

For my PNA + options mix, I can look in the datasheet for the frequency range I am operating at and I get the following specs (for 2.0-3.2 GHz):

Max leveled Power: 8dBm (filtered, spec)/10 dBm (hi power, spec), 10 dBm (filtered, typ) 13 dBm (hi power, typ)

Power sweep range: 35 dB (spec), 40 dB (typ)

There is a footnote that says 'Either Port can be used as the source port. Source in Hi Pwr mode where applicable'

I am not too sure how to interpret 'where applicable' - does this mean <3.2 GHz where the harmonic filtering kicks in?

Assume that I am conservative, so I will take specs and not typicals. Also assume that I have negligible losses after the test port (some high quality test port cables). Assume that source atten is 20 dB.

I know that Pmax will be 8 dBm - 20 dB = -12 dBm (spec'd)

What is spec'd Pmin? Is Pmin -30 dBm - 20 dB = -50 dBm (see Dara post: min power at 0 dB atten is -30 dB). In which case the spec'd power sweep range is 38 dB. But the spec sheet says the spec'd sweep range is +35 dB.

Now, let's say that I have not interpreted the 'where applicable' footnote correctly. So, in Hi Pwr mode:

Pmax= +10 dBm - 20 dB = -10 dBm

Pmin = -30 dBm -20 dB = -50 dBm

which is a range of 40 dB, whereas the spec is 35 dB.

So, where is the discrepancy coming from?

Thanks

Andy

For specification, the minimum power level specified is exactly the max power spec minus the power range spec. In your example, it is max power minus 35 dB. Thus, for +8 dBm spec power, it is -27; for +10 dBm (high power) it is =25. Of course this makes sense in that if you decrease the loss, the max power and min power must both go up. The active entry values are limited at =30 to +30 of the attenuator setting, and the actual max power available may be as much as +21 dBm in some bands (3.2-18 GHz for example).

With ALC off, the power range is expanded greatly, but it is not at all specified.

However, as a practical matter, I use -30 dBm all the time for the minimum, specially when I do a source power cal. there is always some additional loss to get from the test port to the DUT and that means the ALC will always operate at least a little bit above it's minimum settable range so any accuracy issues are minimized (even more so if you also use receiver leveling).

Hope this clears things up.

Many thanks for clearing that up...

Andy