NF mixer simulation (SSB or DSB??)

ssb and dsb nf

Dear all,

I have some questions about the simulation result of the mixer. I hope anyone could clarify my problems. Thanks

In my receiver design, I have two down conversion mixer. Mix1 is low IF and Mix2 is zero IF. I am using SpectreRF simulator in QPSS + QPNoise.

Questions:
1) Actually, the simulated NF is SSB or DSB?

2) From the system specification, it will give out the required total NF. I use this value and calculate the required NF value of each building block in the receiver chain. This NF value is DSB or SSB?

Thanks

wccheng

wccheng

1) Actually, the simulated NF is SSB or DSB?

Click to expand...

I think it depends on type of conversion in your receiver. Please try to check attachment file.

2) From the system specification, it will give out the required total NF. I use this value and calculate the required NF value of each building block in the receiver chain. This NF value is DSB or SSB?

Click to expand...

Terms of SSB and DSB NF are specified for mixers only. So you should just understand what mixing type you are using and then calculate NF for it.

spectrerf qpss option setting

Dear all,

Actually, I am doing UWB receiver design and the frequency is around 3.1 to 4.7GHz. Up to now, the NF of receiver chain, included Tx/Rx switch + LNA + mix 1 + mix2, is 7.5dB around. The voltage gain is around 33dB. I have tried to tune all possible things in order to further decrease the NF. It is unsuccessful. Does 7.5dB NF is enough for the WiMedia requirement? I am curious that NF of the receiver chain as low as 4.8dB?

Thanks

I think the for the IF mixer, you should use SSB, for the second mixer, you should use DSB.

From the system point of view, I think DSB is correct

fanshuo said:

I think the for the IF mixer, you should use SSB, for the second mixer, you should use DSB.

From the system point of view, I think DSB is correct

Click to expand...

Hi Fanshuo,

You mean the simulated NF result of my receiver chain is SSB? The specification value is DSB. Therefore, my simulated NF should minus 3dB?

thanks

in SpectreRF, you can specify whether the NF is DSB or SSB, And I believe the default setting is DSB.

I remember that you mentioned the NF problem before, it might caused by this setting.

In the Direct Plot Form, there are "Noise Figure" and "NFdsb" option selection. "Noise Figure", it is single side band noise. "NFdsb", it is double side band noise.

fanshuo said:

in SpectreRF, you can specify whether the NF is DSB or SSB, And I believe the default setting is DSB.

I remember that you mentioned the NF problem before, it might caused by this setting.

Click to expand...

hi!
i am trying to simulate the NF of a UWB mixer for a RF signal from 3.1G to 4.8G?
do you suggest to try the Qpnoise&Qpss or the PSS&PSP?
thanks in advance.

imar said:

hi!
i am trying to simulate the NF of a UWB mixer for a RF signal from 3.1G to 4.8G?
do you suggest to try the Qpnoise&Qpss or the PSS&PSP?
thanks in advance.

Click to expand...

First you have to choose PSS or QPSS as master analysis according to your situation.
Do you know difference of PSS and QPSS ?

Then combine slave analysises such as PSP(QPSP), Pnoise(QPnoise).

If you don't do wrong setｔing, any combination of PSS/PSP, PSS/Pnoise, QPSS/QPSP, QPSS/QPnoise always give same results.

But usually many people do set wｒong setting in PSP and QPSP.
Read manual of Spectre surely.