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What is the major difference in layout for RF IC?

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dinesh agarwal

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what is the major different in layout for RF ic

means what is main area of concern during RF IC layout
 

RF IC layout

Higher Frequencies means your layout are more compact and robust. Transistor needs to respond faster.
You're also dealing more with all kinds of inductor layout...which in case of low freq layout you just draw all types of devices except the inductor.
 

Re: RF IC layout

Your main concern is impedance matching. Use free strip line software to match impedance between components, such as Gain blocks and mixers or any other RF components. (Trace width Vs. K factor of the material of the PC Board.)
 

Re: RF IC layout

Should be parasitic capacitor and resistor reduce.
 

Re: RF IC layout

when you comes to RF IC layout rather than analog & mixed siganl you hace to be extra careful about parasitics, since you have to working on high frquency. at high frquency you will not analyse which parasitic will come into picture and kill your performance

1. Your layout should be simple and compact
2. Use a metal with low resistivity (TOP) wherever possible
3. Use wide and short metals and many more

Try to include all your layout parasitics into simulations to see your circuit performance at high frquency.
 

RF IC layout

Hi TVincent, I think you comment mainly applies to RF PCB design, not so much to RF IC design. In IC design I wouldn't be too much concerned about impedance matching (since the connections are much shorter than a wavelength, and since in CMOS on chip it is mostly about voltage, not so much power transfer). Focusing on on-chip inter-component impedance matching will involve very large structures which only make the die size bigger (i.e. more expensive) while bringing only very limited benefit. Lastly, when focusing on traditional 50Ohm matching, on chip power requirements are excessive when compared with low power designs that only focus on voltage transfer. Only for the LNA input input matching needs to be considered (but this can be on PCB level) and the same goes for the RF PA.
 

Re: RF IC layout

Hi TVincent and Nschutten,

Just want to add. I think on chip matching is not necessarily to keep equal to standardized 50 Ohms impedance. The most important thing to is to keep matching even it takes place at other absolute values of impedances. What do you think?
 

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