Using Network measurement Mixer S21 Gain is important ??

[ttkane]

Title is important??

I'd design mixer by bjt then bpf to backend circuit.
By matching mixer in port at 50ohm and return loss < -15dB.

My manager told me that i need to use Network by calibrate S21 and measurement Mixer+bpf response
that S21 gain must be above 25dB.

His argument is correct or not ??

have a really paper or http could proved it ?

please suggest me thanks

 

[WimRFP]

Hello,

25 dB insertion gain for a (simple) BJT mixer is very high (too high I think). If you want to use your VNA for mixer measurements, you need a VNA with frequency translation/offset capability as your output frequency doesn't equal the input frequency.

You can use your VNA to measure the Return Loss of the mixer + PBF, but you may use a signal generator (maybe the VNA as a signal source) and spectrum analyzer to measure the output of the mixer.

 

[ttkane]

Thanks for your best reply.
I know Mixer block features measurement by using VNA and I'm ready it.

But my manager means that using VNA measure Mixer+BPF response with no SG and Calibrate S21 Thru and measuring it.
i'm not sure that is right procedure and did't understand what's means about.

 

[WimRFP]

Hello,

If you need to measure S11 and S21, you need to calibrate the VNA before it can make the corrections for cable length and cable loss. Mostly this goes with a Short, Open, Load termination and a Thru. The short, open and load you need to calibrate a single port (for example for measuring S11, VSWR or Return Loss only).

For measuring S21, S12 or Insertion gain/loss, you need the "thru" connector also. It is mostly called a "SOLT" calibration procedure. Where SOLT stands for Short, Open, Load and Thru.

There are other calibration procedures like "TRL" (Thru, Reflect (mostly short) and Load). You should consult your VNA's manual about the calibration procedures.