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Simulating gilbert cell mixer layout

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evilguy

evilguy

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simulation isue

i have done my gilbert cell mixer layout using L-edit from tanner. all i have is tspice version 11. can somebody help me in simulation. beside dc operation point analysis dan transient analysis, can somebody tell me what simulation i have to to compute my mixer gain and freq response. i really dont know at what frequency my mixer can operate. please help me.

if somebody has Hspicerf or better simulation tools that can simulate my mixer, please help me. i can email my mixer netlist. hopefully someone can simulate it for me. My uni dont have cadence or ads for me to simulate my design.
 

Re: simulation isue

for that u need to do AC analysis
 
Re: simulation isue

please help me. how to do ac analysis. just put in .ac in netlist? what can i get if i do ac analysis. if i'm not mistaken if we do ac analysis, both rf and lo frequency will be sweep. so how can we know the frequency response of the mixer circuit.
 

Re: simulation isue

i have worked a lot on mixers and can help you! but i dont understand clearly what simulator u r using! can u be bit clear n precise? do u have access to cadence? u need PSS analysis to compute different parameters
 

Re: simulation isue

i'm a beginner. thanks for trying to help me. i dont have access to cadence. but i think i can manage to get ads. that the best i can do for now. can you instruct me on ads instead of cadence software? i have manage to import my layout netlist to ads. i can simulate it in ads environment.
 

Re: simulation isue

I havent used ADS but i know ADS uses harmonic balance to compute the different parameters..u can always look up help in their manual or even google up! U need to do
a) conversion gain analysis
b) Noise Figure
c) IIP3 and 1-dB compression point using harmonic balance
I know Cadence well so if u can get hold of cadence I can xplain it
 

Re: simulation isue

For doing AC analysis, You need to do following things

-- select an AC source as an input it should not a fix frequency sinusoidal source.

-- now insert AC analysis command and utilize the various option accrding to ur use in AC analysis command.

-- insert o/p command for AC and select the nodes on which u want to view Ac analysis
 

Re: simulation isue

preet said:
For doing AC analysis, You need to do following things

-- select an AC source as an input it should not a fix frequency sinusoidal source.

-- now insert AC analysis command and utilize the various option accrding to ur use in AC analysis command.

-- insert o/p command for AC and select the nodes on which u want to view Ac analysis
Click to expand...

thanks... but mixer has 2 input. first is LO and second is RF. then how to to AC analysis?

what are the ideal conversion gain, 1dB compression point, noise figure and IIP3 for a mixer. i just want to compare it with my mixer if i've successfully compute all of that.
 

Re: simulation isue

I have used ADS to compute the conversion gain, 1dB compression point, noise figure and IP3. but when i tried to compute IP3 i face some problem. the problem is at my IF freq my upper and lower intermodulation tone is not identical. mean that at frequency (2F1-F2)-LO and (2F2-F1)-LO dont have the same amplitude. so if i compute IP3 using upper sideband, i will get different value id i compute it in lower sideband. so how to calculate it? i've read it we can try increase LO order and max order in HB simulation to solve this. but after i did it, i still cant solve the prob.
 

Re: simulation isue

here is what i got when i do two tone test in ADS. please refer to the atachment below. how to compute IIP3? the two sidebands do not have the same amplutude? (m1 !=m3 and m2!=m4). which side band i should use to compute the IIP3? i use the equation: IIP3=1.5*m1-0.5m2. this equation i get from reading one of tutuorial for mixer design in ADS. please help me.

i've simulate my mixer and i got my 1dB compression point at 0dB. so according to the theory, my IIP3 should be 10dB higher that 1dB compression point. Is this rule always true? i think mine is not 10dB. probably below 10dB.
 

Re: simulation isue

evilguy said:
i have done my gilbert cell mixer layout using L-edit from tanner. all i have is tspice version 11. can somebody help me in simulation. beside dc operation point analysis dan transient analysis, can somebody tell me what simulation i have to to compute my mixer gain and freq response. i really dont know at what frequency my mixer can operate. please help me.

if somebody has Hspicerf or better simulation tools that can simulate my mixer, please help me. i can email my mixer netlist. hopefully someone can simulate it for me. My uni dont have cadence or ads for me to simulate my design.
Click to expand...

Can u attach ur layout file so that i can aware with errors...
 

Any one Could you able to post the Gilbert cell or any mixer circuit for Tspice Net list here it might be useful to my Work..
Thanks in advance..
 

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