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Simulating gilbert cell mixer layout

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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.
 

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Re: simulation isue

for that u need to do AC analysis
 

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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.
 

designtech

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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
 

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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.
 

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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
 

preet

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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
 

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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

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.
 

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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.
 

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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.
 

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Re: 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.

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

simon.harpham@ieee.org

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kalidasascreator

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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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