Measuring LNA s-parameter on wafer using Agilent 8722es

[chunlee]

LNA measurement

i'l design a common-gate LNA using CMOS technology. the input is matching to 50ohm and the output port will resonance at the desired frequency. I wish to measure the LNA s-parameter on wafer using Agilent network analyzer 8722es.

can i measure the s parameter without matching output port to 50ohm? is it the s parameter measured by matching output to 50ohm and without matching to 50ohm is same? how to convert it?

thanks a lot...

 

[mwmmboy]

Re: LNA measurement

S parameters are the measure of the power flowing into or out from a circuit.
Can you explain more deeply what are you doing?

Bye

 

[Kit-the-great]

LNA measurement

You can convert S-parameters to any matching ports. See it in any common book like Electrical Engineering Handbook or **broken link removed**
But the measurement error will be depend on matching port impedance.

 

[vfone]

Re: LNA measurement

The main idea of measuring S parameters direct on wafer is to don’t have any matching circuit.

The matching circuit has to follow the S parameters that you measured (to obtain Gain, Noise Figure, Power, etc).

Finally you can measure the combined S parameters (LNA + matching) to publish in the datasheet.

 

[chunlee]

Re: LNA measurement

i read many papers about LNA, most of the design don't match their output port to 50ohm.

How can i measure the voltage gain of my LNA if i just let the output port of LNA resonance at operating frequency(high impedence)?

is it the voltage gain equal to S21?

 

[boy]

LNA measurement

sometimes, the output does not match to 50 ohms because stability issues. S21 is a power gain not voltage gain.