Help me design an impedance match circuit for 32-48Mhz

[david753]

the match meter impedance

I use RLC meter to measure the impedance of analog input of AD9057.
Because the input bandwidth is from 32MHZ to 48MHZ, i measure 101-240j(32MHZ), 69-206j(40MHZ), 50-173j(48MHZ), respectively.
I'd like to design a match circuit that can transfer input impedance at all bandwidth(32-48MHZ) to ideal 50OHM as possible.
Does anybody can help me to design it?

 

[flatulent]

Re: impedance match

Be aware that this network will have a not constant voltage frequency response and your readings on the converter will be in error.

 

[hcseu]

impedance match

may be you should remeasure the imput impedance with VNA,and get s parameter files
and inport it into the ADS
then select a topology of the match network
and optimize it in ADS

 

[djalli]

impedance match

Does AD9057 has some datasheet so you can start from there?

 

[david753]

Re: impedance match

I already measure the impedance of analog input of AD converter.
The values are as following, respectively.
79-297j /32MHZ
51-234j /40MHZ
40-197j /48MHZ

How do I simulate it on ADS depends on the terminator is NOT at 50ohm?
Usually, I use TERM=50ohm at simulation-Sparam category.
But, I have no idea when the terminator is NOT 50ohm.

Added after 52 seconds:

I already measure the impedance of analog input of AD converter.
The values are as following, respectively.
79-297j /32MHZ
51-234j /40MHZ
40-197j /48MHZ

How do I simulate it on ADS depends on the terminator is NOT at 50ohm?
Usually, I use TERM=50ohm at simulation-Sparam category.
But, I have no idea when the terminator is NOT 50ohm.

Added after 56 seconds:

I already measure the impedance of analog input of AD converter.
The values are as following, respectively.
79-297j /32MHZ
51-234j /40MHZ
40-197j /48MHZ

How do I simulate it on ADS depends on the terminator is NOT at 50ohm?
Usually, I use TERM=50ohm at simulation-Sparam category.
But, I have no idea when the terminator is NOT 50ohm.

 

[Mazz]

Re: impedance match

I'm sorry but I think you should take a look at your measurements because probably is wrong.
Actually A/D Converters have capacitive inputs and this one is not different (from the datasheet the impedance should be 2pF//150kOhm). So What you'll measure should be very close to the edge of the Smith chart (mag of S11 is like 0.999), and will be difficult to match.
Infact A/D works unmatched! What usually is imprtant is voltage transfer, not power transfer, so you don't need to match.
Usually designers looks only if the driver is capable to drive the capacitive load (means that they provide the right current) of the A/D+board parasitic.

I hope it can help
Mazz