spectrum s-parameter measurment

[sedighe]

hi friends

i wanna design a RF power amplifier by using SR706(polyfet transistor). at first i need s-parameters for high power biasing.
i have a network analyser (Anritsu MS620J). i need your help to answer me if i can use this device for musearing S-parameters. and guide me how?

thanks

 

[psmon]

2-port measurement? Search Agilent, Anritsu websites.. Many articles available.

 

[Mosieur_Oiso]

Hi there,
Why don't you simply use the Sij parameters provided in the datasheet? Measuring Sij parameters of high power transistors must be done by (or with) experienced technician. Accurate measurement of S22 requires little attenuation on Port2 of VNA. One simple mistake and you kill the Port2 of your network analyzer…
Mosieur_Oiso

 

[vfone]

High power S11 and S21 you can measure theoretically without problems using a network analyzer. Beware that you need a high power attenuator at the output do don’t damage the NA. SR706 can deliver 300W (+55dBm), so you need at least 40dB attenuation after the amplifier.

To measure the proper output impedance at high power is better to use a Load Pull system like Maury or Focus.

ww.maurymw.com
www.focus-microwaves.com/

 

[sedighe]

High power S11 and S21 you can measure theoretically without problems using a network analyzer. Beware that you need a high power attenuator at the output do don’t damage the NA. SR706 can deliver 300W (+55dBm), so you need at least 40dB attenuation after the amplifier.

To measure the proper output impedance at high power is better to use a Load Pull system like Maury or Focus.

ww.maurymw.com
www.focus-microwaves.com/

for 55dBm power in the output of the transistor i need aboad 45dBm in the Gate of transistor. i think it is not posible for the Network to support it. is it?
should i use external driver? and what happens for the matching if i use another driver in the input?
thank again for all of your help

Added after 5 minutes:

Hi there,
Why don't you simply use the Sij parameters provided in the datasheet? Measuring Sij parameters of high power transistors must be done by (or with) experienced technician. Accurate measurement of S22 requires little attenuation on Port2 of VNA. One simple mistake and you kill the Port2 of your network analyzer…
Mosieur_Oiso

hi friend
S-parameter in datasheet in available for small signal and not in the larg signal, and there is a big diffenence between them.
thanx for your Reply Mosieur

 

[Mosieur_Oiso]

Hi there,
According to what I can see on the datasheet of the SR706 available here: http://www.polyfet.com/dsheet/SR706.pdf Zin and Zout are indicated for Vdd=28V, Idq=1200mA, and Pout=300W, isn't it what you want?
Just like vfone mentioned, the best way to measure S22 at high power is using an automated Load Pull system, and again, if you are not experienced in this field, I would recommend not to do it just by yourself...
You can use a preamplifier on Port1 of a VNA and still measure S11 of DUT. If you have R, A and B channels available on your VNA, you need to insert a coupler between the preamplifier and the DUT, and connect CPL to R channel of VNA, and ISO to A channel of VNA (and calibrate with these).
Mosieur_Oiso