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aaron_do Senior Fellow Offline Posts: 1398	High-Q inductor options Dec 07^th, 2011, 3:59am Hi all, just wondering if anybody cares to share some high-Q inductor options. For instance, 1) Chip inductors. I've seen Q up to 150 at 1 GHz, but I'm not sure what's typical. 2) Bondwire Q seems to go up to about 25 at 1 GHz. 3) MEMs? 4) IPD? anything I've missed out? thanks, Aaron
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raja.cedt

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Re: High-Q inductor options
Reply #1 - Dec 7^th, 2011, 4:23am

hello,
1. on chip inductor Q won't be 150 i guess, it's much smaller than that, if not all VCO Q at this frequency range (like DCS, GSM) will be dominated by varactor but in reality inductor Q dominates.

2. Bond wire inductor Q will be high.

I would like to add selective substrate etching beneath the inductor technique to increase the Q but with reliability compromise.

what do you mean by IPD?

Thanks,
Raj.

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loose-electron

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Re: High-Q inductor options
Reply #2 - Dec 7^th, 2011, 9:11am

on semiconductor chip or oiff chip?

better performance off chip, see things like Digi-Key and do component searches.

Even off chip though, your network Q is going to be worse than the inductor due to board parasitics.

Higher order networks?
If BPF performance is what you are looking for, then the higher order LC networks may be a possible path.

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ACWWong

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Re: High-Q inductor options
Reply #3 - Dec 7^th, 2011, 9:34am

raja.cedt wrote on Dec 7^th, 2011, 4:23am:

what do you mean by IPD?

Thanks,
Raj.

Integrated passive device.... not to be confused with "chip" inductor which means a surface mount component.

In terms of chip inductors, coilcraft are normally best for performance... but not cost. Q very much depends on technology; multilayer or wirewound.

I'd be interested in gyrator performance too Wink

especially at RF freqeuncy using modern sub-micron technologies.

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raja.cedt Senior Fellow Offline Posts: 1516 Germany	Re: High-Q inductor options Reply #4 - Dec 7^th, 2011, 10:41am hello ACWWong, why u need gyrator, r u talking abut active passives? Thanks, raj.
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loose-electron Senior Fellow Offline Best Design Tool = Capable Designers Posts: 1638 San Diego California	Re: High-Q inductor options Reply #5 - Dec 7^th, 2011, 4:06pm need to define RF frequencies up to 200MHz these days you can do with Op-amps from 100-500MHz gmC will work 200MHz and up traditional "RF" techniques, LC sections and networks. Some overlap... "RF" is a pretty meaningless term these days.
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aaron_do

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Re: High-Q inductor options
Reply #6 - Dec 7^th, 2011, 5:41pm

Hi all,

thanks for the replies. Anyway just so that maybe we can stay on topic, as ACWWong pointed out, by chip-inductors I meant surface-mount. I checked up Murata and the highest Q I saw was around 150 at 1 GHz.

Quote:

I would like to add selective substrate etching beneath the inductor technique to increase the Q but with reliability compromise.

does that fall under MEMs? What kind of Q is possible? How about cost-wise? It sounds very expensive.

Quote:

Even off chip though, your network Q is going to be worse than the inductor due to board parasitics.

So for example, if I want to design a VCO with a tank inductance of 5 nH, what is the maximum tank Q I can get, and what kind of technology would I be looking at?

thanks,
Aaron

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raja.cedt

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Re: High-Q inductor options
Reply #7 - Dec 7^th, 2011, 7:17pm

hello,
could you please point me the reference where you have seen Q~150 (i am so curious)

regarding your last question, it's tough to say which tech and it wont change with technology more or less. Inductor Q effected by 1. high from the substrate 2. size of the inductor 3. width of the top metal. So if you have more top metal then it's good for Q, by tweaking the design (green-house formulas) by selecting proper topology (with ground shield, differential coil) you can get better Q.

thanks,
raj.

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aaron_do

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Re: High-Q inductor options
Reply #8 - Dec 7^th, 2011, 9:45pm

Hi Raj,

here's a document from Murata with a lot of RF inductor info. Check out page 155 for a very high Q inductor.

http://www.murata.com/products/catalog/pdf/o05e.pdf

Also, I think you misunderstood my question. When I asked which technology would I be looking at, I was not refering to which process node. I mean what kind of technology such as IPD, surface mount components, MEMs, Bondwire etc. i.e. how can I get the best possible Q, and as a side question, in practice, what options do people normally use. I think bondwire is fairly commonly used as long as the inductance value doesn't need to be too large.

regards,
Aaron

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raja.cedt Senior Fellow Offline Posts: 1516 Germany	Re: High-Q inductor options Reply #9 - Dec 8^th, 2011, 3:44am hello, yes you are correct, Bond wire Q will be higher more or less. Thanks for the doc. Thanks, raj.
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loose-electron Senior Fellow Offline Best Design Tool = Capable Designers Posts: 1638 San Diego California	Re: High-Q inductor options Reply #10 - Dec 8^th, 2011, 11:17am Bond wires can be inconsistent on the value due to the variance in the mounting, length and height above package ground.
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aaron_do Senior Fellow Offline Posts: 1398	Re: High-Q inductor options Reply #11 - Dec 14^th, 2011, 7:03pm Quote: Bond wires can be inconsistent on the value due to the variance in the mounting, length and height above package ground. Compared to on-chip inductors I guess that's true, but how much variation is typical? thanks, Aaron
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raja.cedt Senior Fellow Offline Posts: 1516 Germany	Re: High-Q inductor options Reply #12 - Dec 15^th, 2011, 1:40am hello arron, You can refer Wireless cmos frequency synthesizer design book. It has chapter on Bond wire inductance, and unfortunately it depends on many parameters like bonding angle and bond wire length which are very strongly depends on the bonding environment. In this book he shown variation is around 30%. Thanks, Raj.
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aaron_do Senior Fellow Offline Posts: 1398	Re: High-Q inductor options Reply #13 - Dec 15^th, 2011, 6:57am Hi Raj, thanks for the reference. Are you sure you remembered the number correctly? I checked up the same reference and it mentioned the total variation to expect was on the order of about 6%. regards, Aaron
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raja.cedt Senior Fellow Offline Posts: 1516 Germany	Re: High-Q inductor options Reply #14 - Dec 15^th, 2011, 7:48am hello, let me check, but 6 is very small number seems. Soon i will provide exact number... Thanks, Raj.
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