how we do spectre noise analysis

spectre noise analysis

hi,
I have a problem in SPECTRE
I wanted to measure the input voltage and current noises of an current feedback opamp

I have finished my DC analysis but havent yet figured out how to proceed with calculating noise V^2 and noise i^2 at input of opamp

though i could figure out that i need to check the NOISE option in the ANALYSES menu of the ANALOG ENVIRONMENT window, iam unable to proceed further

I guess i have made my question clear, could anyone tell me how to perform noise analysis in spectre......

Thanks
welcome to comments and discussion[/youtube]

spectre noise

I have done the noise simulation based on noise simulation in the Analog Design Environment (ADE). I have chosen voltages for the input and output.
Then I got a nice curve from 1Hz to 1GHz.
How to get the total noise at the input of the OpAmp ?
In the calculator, there is a choice for RMSnoise that give a realistic figure.
Is that OK ?

spectre noise simulation

In Cadence ADE, in the results menu, I can get the ideal contribution of the main xx device to the noise.
How can I get the contribution of a selected device with the calculator ?

noise simulation spectre

As far as I know you should use Noise analysis provided in the Spectre Analog Environment. For estimating the input noise levels I think you have to use "vsource" instance at the input. With that source and Direct Display form options you can directly plot the input and output noise as well as NF etc....I used this method long bakc with IC 5.0. I dont know with the curret versions there is any change in the procedure.

noise analysis spectre

i had done the .noise analysis, but i think the result is uncorrect! i hope: pls tell us in detail if someone know how to do!

noise spectre

You will select noise analysis.Then frequency as sweep variable.The important is to set the correct sweep range.So usually for start-stop range we put 1.5-2 times the bandwidth of your circuit that is if your bandwidth is 1Mhz then you will put to start-stop range START:0 STOP:1.5Mhz. Then for output noise you will select voltage(probe is for currents) then you click on select and then select the output net on your schematic. For input noise select voltage and then as before hit select and choose your input voltage at the schematic. Very important is at options to select save all!.After you run the analysis go to Results=>Print=>Noise Summary.Then select for type integrated noise, for unit V^2 or V then for range as before(it must be the same) 0 to 1.5MHz.Then select include all types and at truncate&sort put at top a big number to include all components of your circuit. For example if your circuit is big write at top 80.And then OK.At results display window (at the end ) there will be the rms noise

noise analysis in spectre

If the noise simulation is not reasonable,check whether you have Kf,Af parameters in your transistor model file.