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udaykumarchintala Junior Member Offline Posts: 22 ahmedabad	cmos down conversion mixer Feb 12^th, 2008, 10:36am Hii, I want know the design methodology for the down conversion mixers............help me.........
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Stefan Senior Member Offline Posts: 124	Re: cmos down conversion mixer Reply #1 - Feb 12^th, 2008, 11:06am There are plenty of books available. Check for Lee, Razavi, Gray, Johns, Baker ... Maybe also check for the phrases please, kind or other complimentary flowers of speech Kind Regards, Stefan
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udaykumarchintala Junior Member Offline Posts: 22 ahmedabad	Re: cmos down conversion mixer Reply #2 - Feb 17^th, 2008, 5:34am hii, What is the effect of matching circuits on the performance of the mixer?????Is it compulsory to design them?????????? thanks in advance, uday
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Stefan Senior Member Offline Posts: 124	Re: cmos down conversion mixer Reply #3 - Feb 18^th, 2008, 12:18am That strongly depends on the rest of your design. A mixer not capable of driving the load is useless. However you can simulate the mixer with any matching around it that you desire, whether that's a "real world simulation" is another question ... btw. check your "?"-key, I guess it's stuck someway. Regards, Stefan
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udaykumarchintala Junior Member Offline Posts: 22 ahmedabad	Re: cmos down conversion mixer Reply #4 - Feb 25^th, 2008, 5:08am Hi, In principle for a Mixer the LO signal is a square wave,but in most of the papers I have gone through they have carried out the simulations by taking the sine wave as a LO signal.Why?What is the difference?Do we get the desired output in both the cases? Thanks in advance Uday
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Stefan Senior Member Offline Posts: 124	Re: cmos down conversion mixer Reply #5 - Feb 25^th, 2008, 5:10am Sine-Signals do work better with simulations like HB or alike ... It's not THAT realistic then, but the higher order harmonics are often of no interest, because they are filtered sufficiently.
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didac

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Re: cmos down conversion mixer
Reply #6 - Feb 25^th, 2008, 12:23pm

Hi,
You should always make a design as close to the reality as possible, in this case the question is:which kind of signal will deliver the oscillator to the mixer? At very high frequencies it's not as easy as it seems to generate a good square wave, but if you consider the phase-noise requirements(to avoid reciprocal mixing) tunned oscillators generating a sine wave usually are more suitable to achieve the target specifications.

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udaykumarchintala Junior Member Offline Posts: 22 ahmedabad	Re: cmos down conversion mixer Reply #7 - Feb 27^th, 2008, 11:23am hii, How do we design a mixer for a desired gain,generally in a cascode the gain is gmRl.but in case of mixer how do we design for the same at a high frequency and the output frequency is also different.How to get a such a large gain at GHz ranges? Thanks in advance uday
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loose-electron Senior Fellow Offline Best Design Tool = Capable Designers Posts: 1638 San Diego California	Re: cmos down conversion mixer Reply #8 - Feb 28^th, 2008, 4:46pm Mixers freqeuently dont have that much gain (12db at an absolute max? YMMV) :-/but the gain is in around them, pre and post. Jerry
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udaykumarchintala Junior Member Offline Posts: 22 ahmedabad	Re: cmos down conversion mixer Reply #9 - Mar 1^st, 2008, 1:27pm Hi, In some of the previous designed mixers they used folded cascode structure, the only difference between folded cascode and these mixers is that a switching transistor .....is it right?Is the design procedure is same? Thanks in advance
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didac

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Re: cmos down conversion mixer
Reply #10 - Mar 2^nd, 2008, 4:03am

Hi,
Folded mixers are useful if your concern is voltage headroom since you don't have all the elements stacked one over the other. But beeing a different circuit topology brings to other design trade-offs like:between Vdd and the transconductor is a current source, a resistor(both lower the headroom),an inductor(if it's not a bondwire the finite Q could be losses),a LC tank tunned at fo?. Also the switching pair is a PMOS so it should be taken into account it's suitability in function of your operating frequency and technology.
Hope it helps,

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udaykumarchintala Junior Member Offline Posts: 22 ahmedabad	Re: cmos down conversion mixer Reply #11 - Mar 2^nd, 2008, 8:53am Hi, Thanks for your reply..... what my question was the design procedure of folded cascode mixer is same as the folded cascode except the switching transistor? thanks...
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didac Senior Member Offline There's a million ways to see the things in life Posts: 247 manresa,spain	Re: cmos down conversion mixer Reply #12 - Mar 2^nd, 2008, 9:11am Hi, I apologize if my answer was unclear. The design procedure it's the same for sizing(gm,rload,bias,LO amplitude), but my point was that beeing a completely different topology you should consider the specific issues of the circuit.
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udaykumarchintala Junior Member Offline Posts: 22 ahmedabad	Re: cmos down conversion mixer Reply #13 - Mar 2^nd, 2008, 9:36am Hi, thanks a lot....... Can I find any tutorial for this design procedure? Thanks....... Uday
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didac Senior Member Offline There's a million ways to see the things in life Posts: 247 manresa,spain	Re: cmos down conversion mixer Reply #14 - Mar 2^nd, 2008, 10:50am Hi, You can check: http://weble.upc.es/rfcs/Material/mixer_chandra.pdf http://www.zen118213.zen.co.uk/RFIC_Circuits_Files/MOS_Gilbert_Cell_Mixer.pdf Or the chapter of Mixers of Thomas Lee Book:"The Design of CMOS RFIC". Hope it helps,
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