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ADS - 10pf Capacitor in TSMC RF CMOS 0.18 Tech

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rvn176

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I'm desiging a mixer in ADS TSMC RF CMOS 0.18 v5 technology. I need to have 10pf capacitors. But the MIM CAP in technology is limited to 30um*30um which results in 1pf capacitance. Does this means that I te only way is to put 10 of these?

There is also another cap option named MOS CAP. But it seems it's only for variable capacitors, and I don't know how to design it. It has b and g parameters. Can it be used for fixed capacitors too? How? what are b and g?
 

You should put 10 times 1pF MiM cap parallel..
If your operating frequency is pretty high, then simulate them in Momentum to check the parasitic inductances and stray capacitances..
 

Hello, I am doing on-chip switched capacitor DC/DC converter and I also need a large amount of capacitor bank. Someone recommends me to use MOS capacitor to achieve large capacitors. But I find MOS capacitor is dependent on voltage and its capacitance may change during working process. Therefore, it may be not reliable. What do you think about it? I believe that to get 10 pF, you need put 10 of these capacitors in parallel. Normally a desired capacitor value is created by adding unit capacitors togetherin parallel. Having an unit capacitor has advantages as the mosaic layout structure can be designed to managed variability and reduced mismatches. Another important reason why the MIM cap are limited to particular size is because these are macro blocks that have been characterise/modelled by the foundry over a limited component parameter ranged.
 

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