Re: [SI-LIST] : Parallel Plate Capacitance for Bypass

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From: Larry Smith (ldsmith@lisboa.eng.sun.com)
Date: Mon Mar 27 2000 - 17:05:14 PST


John - Capacitor measurements are kind of tricky. HP has some good
equipment, but accuracy dimishes as we try to measure low impedances
(less than 50 mOHms) at high frequency (100's of MHz). The
instrumentation industry has not really caught up with our need to
measure this stuff. Most of the measurements use a reference impedance
of 50 Ohms. Unless you go to extra ordinary measures, impedance
measurements below 10 mOhms should be questioned. Istvan Novak has
published some nice articals on the problems and some solutions of low
Z, high frequency measurements at the 1999 and 2000 Design
Conferences.

        http://home.att.net/~istvan.novak/papers/papers.html
        
Tanmoy Roy and I found that in the process of calibrating and
compensating the HP gear, we sometimes compensated out the thing that
we were trying to measure. We used the HP 4291A and 4194A instruments
and a 16193A fixture. We calibrated with the little metalic cubes.
But I found that I could get just about any ESR that I wanted by
applying different amounts of pressure to the fixture. I think it
depended on the contact resistance for both calibration and
measurement. Some of your ESR's below look unrealistically low to me.
Depending on how I compensated, I could manage to get any indutance I
wanted, including negative numbers..! We eventually decided that we
were better off calibrating to the end of an SMA connector and
soldering a capacitor down to it. We skipped the compensation because
it tended to subtract out contact resistance, which was often higher
than the ESR we were trying to measure. There are more comments on ESL
and ESR in our paper at:

        http://www.qsl.net/wb6tpu/si_documents/docs.html
        
The inductances that you are measuring may be appropriate for the
partial inductance of the capacitor by itself. But when you mount the
capacitor on solder pads and connect it to power planes with vias, the
inductance will be more like 500-1000 pH. That is the capacitor as it
is presented to the system.

We find that a good way to measure a decoupling capacitor is to use a
network analyzer to make an s21 measurement on a set of PCB power
planes. Solder down the cap to it's normal solder pads. The measured
impedance profile is similar to what an actual system will see. This
works for capacitors that are large in value compared to the
capacitance of the power planes. To get ESR, you don't need the power
planes. Just solder the cap to port1 and port2 of the VNA (sort of
like a 4 terminal resistance measurement). Then ignore what ever
inductance you get.

regards,
Larry Smith
Sun Microsystems

> From: jrbarnes@lexmark.com
> X-Lotus-Fromdomain: LEXMARK@LEXMTA
> To: si-list@silab.eng.sun.com
> Date: Mon, 27 Mar 2000 08:57:04 -0500
> Subject: Re: [SI-LIST] : Parallel Plate Capacitance for Bypass
> Mime-Version: 1.0
> Content-Disposition: inline
>
> Bob,
> I am giving an informal seminar on bypass capacitors to my department on
> Wednesday. As part of my preparations, I measured one sample each of:
> * Surface-mount technology (SMT) capacitors that we have used on network
> adapters over the last
> 3-4 years.
> * Some pin-through-hole (PTH) capacitors that I found in our lab.
> * SMT capacitors that I found in sample kits in the Electromagnetic
> Compatibility (EMC) Lab.
>
> Here is the data, minus Lexmark part numbers--
>
>
>
> bypass.wq1 John Barnes 3/16/2000
>
> Capacitors measured on HP 4195A Network/Spectrum Analyzer
> with HP 41951-61001 Impedance Test Adapter from 100kHz to 500MHz
> fc is resonant frequency (phase goes through 0 degrees) or
> frequency of lowest impedance if stayed capacitive & lossy (tantalums, Y5V's)
> ESR, cap, ESL of equivalent series-RCL model
> Radial capacitors measured with 1/8-inch leads
> Had to put some large capacitors on edge & raise them slightly
> to keep resonances from fooling the HP 4195A
>
>
> Meas.
> Calc. Nom.
> Nom. Case WV Fc ESR Meas. ESL Fc
> Fc
> Cap. Size Die. (V) Part Number (MHz) (mohm) Cap. (pH)
> (MHz) (MHz)
> ----- ------ ---- ---- ---------------------------- ------ ------ ----- ----- ------
>
> ------
> 22pF 0603 NP0 100 AVX 06031A220KAT2A >500 160 23pF 150
> 2709.6 2770.5
> 220pF 0603 NP0 50 Kyocera 06035A221KAT4A >500 240 200pF 220
> 758.7 723.4
> 1.5nF 0603 X7R 100 AVX 06031C152KAT1A 280.0 330 1.2nF 260
> 284.9 254.9
> 4.7nF 0603 X7R 50 Johanson 500R14W472KV4 230.0 100 3.1nF 130
> 250.7 203.6
> 10nF 0603 X7R 25 AVX 06033C103MAT2A 200.0 62 7.1nF 120
> 172.4 145.3
> 10nF 0603 X7R 50 Johanson 500R14W103KV4 122.0 27 6.0nF 280
> 122.8 95.1
> 10nF 0603 Z5U 25 Johanson 250R14Z103MV4 130.0 20 6.7nF 220
> 131.1 107.3
> 15nF 0603 X7R 25 Taiyo Yuden TMK107BJ153K 87.0 94 14nF 240
> 86.8 83.9
> 22nF 0603 X7R 25 Taiyo Yuden TMK107BJ223K 85.0 55 19nF 190
> 83.8 77.8
> 33nF 0603 X7R 16 Taiyo Yuden EMK107BJ3333 63.0 42 31nF 210
> 62.4 60.5
> 39nF 0603 Z5U 25 Johanson 250R14Z393MV4 84.0 86 18nF 220
> 80.0 54.3
> 47nF 0603 X7R 16 Taiyo Yuden EMK107BJ473K 59.0 28 42nF 170
> 59.6 56.3
> 47nF 0603 Z5U 25 Johanson 250R14Z473MV4 87.0 93 19nF 190
> 83.8 53.3
> 100nF 0603 Y5U 25 AVX 06033G104ZAT2A 43.0 25 78nF 190
> 41.3 36.5
> 100nF 0603 Y5V 25 Taiyo Yuden TMK107F104Z 33.0 20 63nF 380
> 32.5 25.8
> 100nF 0603 Y5V 25 Johanson 250R14Y104MV4 31.0 45 110nF 220
> 32.4 33.9
>
> 270pF 0805 NP0 50 AVX 08055A271JAT2A >500 140 250pF 160
> 795.8 765.7
> 470pF 0805 NP0 100 AVX 08051A471KAT2A >500 140 460pF 160
> 586.7 580.4
> 1nF 0805 X7R 100 AVX 08051C102MAT4A 290.0 620 750pF 410
> 287.0 248.6
> 33nF 0805 X7R 25 Taiyo Yuden TMK212BJ333K 49.0 6 32nF 340
> 48.3 47.5
> 33nF 0805 X7R 50 Taiyo Yuden UMK212BJ333KD 58.0 23 39nF 190
> 58.5 63.6
> 47nF 0805 X7R 25 Taiyo Yuden TMK212BJ473K 42.0 7 34nF 430
> 41.6 35.4
> 47nF 0805 X7R 50 AVX 08055C473JAT2A 40.0 130 44nF 310
> 43.1 41.7
> 47nF 0805 X7R 50 Taiyo Yuden UMK212BJ473K 42.0 4 27nF 490
> 43.8 33.2
> 68nF 0805 X7R 50 Taiyo Yuden UMK212BJ683K 33.0 23 66nF 360
> 32.7 32.2
> 100nF 0805 X7R 25 Taiyo Yuden TMK212BJ104K 23.0 38 100nF 470
> 23.2 23.2
> 100nF 0805 X7R 25 AVX 08053C104JAT2A 25.0 10 46nF 900
> 24.7 16.8
> 100nF 0805 Z5U 50 Kyocera 08055E104ZAT3A 21.0 35 120nF 540
> 19.8 21.7
> 150nF 0805 X7R 16 Taiyo Yuden EMK212BJ154K 18.0 130 130nF 460
> 20.6 19.2
> 220nF 0805 X7R 16 Taiyo Yuden EMK212BJ224K 15.0 47 230nF 470
> 15.3 15.7
> 220nF 0805 Y5V 50 Taiyo Yuden UMK212F224Z 11.0 59 200nF 1000
> 11.3 10.7
> 330nF 0805 Y5V 50 Taiyo Yuden UMK212F334Z 14.0 51 280nF 360
> 15.9 14.6
> 470nF 0805 Y5V 25 Taiyo Yuden TMK212F474Z 8.6 56 380nF 880
> 8.7 7.8
> 680nF 0805 Y5V 16 Taiyo Yuden EMK212F684Z 7.1 65 640nF 520
> 8.7 8.5
> 2.2uF 0805 Y5U 16 TDK CC0805CY5V225ZTR 7.4 69 2.2uF 170
> 8.2 8.2
>
> 10pF 1206 NP0 100 Kyocera 12061A100JAT2A >500 180 10pF 240
> 3248.7 3248.7
> 30pF 1206 NP0 100 AVX 12061A300JAT2A >500 680 31pF 240
> 1845.2 1875.7
> 330pF 1206 X7R Kyocera 1206C331J3B05 490.0 150 310pF 330
> 497.6 482.3
> 1.5nF 1206 X7R 50 AVX 12065C152KAT2A 200.0 450 1.2nF 500
> 205.5 183.8
> 33nF 1206 X7R Kyocera 1206X333K2B05 46.0 38 31nF 360
> 47.6 46.2
> 100nF 1206 X7R 50 Taiyo Yuden UMK316BJ104K 17.0 40 100nF 950
> 16.3 16.3
> 150nF 1206 X7R 50 Taiyo Yuden UMK316BJ154K 11.0 48 130nF 1500
> 11.4 10.6
> 220nF 1206 X7R 50 Taiyo Yuden UMK316BJ104K 11.0 58 170nF 1300
> 10.7 9.4
> 330nF 1206 X7R 25 Taiyo Yuden TMK316BJ334K 9.1 64 270nF 1100
> 9.2 8.4
> 470nF 1206 X7R 16 Taiyo Yuden EMK316BJ474K 8.2 61 370nF 1100
> 7.9 7.0
> 470nF 1206 X7R 25 Taiyo Yuden TMK316BJ474K 8.2 63 420nF 990
> 7.8 7.4
> 680nF 1206 X7R 16 Taiyo Yuden EMK316BJ684K 6.5 68 580nF 750
> 7.6 7.0
> 680nF 1206 Y5V 25 Taiyo Yuden TMK316F684ZF 5.6 65 550nF 1400
> 5.7 5.2
> 1uF 1206 Y5V 25 Taiyo Yuden TMK316F105Z 4.8 70 800nF 1500
> 4.6 4.1
> 1uF 1206 Y5V 35 Taiyo Yuden TMK316F105ZF3 6.4 77 730nF 680
> 7.1 6.1
> 1.5uF 1206 Y5V 16 Taiyo Yuden EMK316F155Z 4.9 70 1.2uF 780
> 5.2 4.7
> 2.2uF 1206 Y5V 16 Taiyo Yuden EMK316F225Z 4.9 71 1.2uF 440
> 6.9 5.1
> 3.3uF 1206 Y5V 16 Taiyo Yuden EMK316F335Z 3.7 60 1.9uF 890
> 3.9 2.9
> 4.7uF 1206 Y5V 16 Taiyo Yuden EMK316F475Z 3.4 66 2.1uF 880
> 3.7 2.5
>
> 680nF 1210 X7R 25 Taiyo Yuden TMK325BJ684K 7.5 69 710nF 440
> 9.0 9.2
> 1uF 1210 X7R 25 Taiyo Yuden TMK325BJ105K 5.5 67 920nF 610
> 6.7 6.4
> 1uF 1210 Y5U 50 Tokin 1E105ZY5U-C203 13.0 72 1.2uF 170
> 11.1 12.2
> 1uF 1210 Y5V 50 Taiyo Yuden UMK325F105Z 4.7 69 1.0uF 1300
> 4.4 4.4
> 1.5uF 1210 Y5V 25 Taiyo Yuden TMK325F155Z 4.2 69 1.0uF 1400
> 4.3 3.5
> 1.5uF 1210 Y5V 35 Taiyo Yuden TMK325F155Z35 5.5 68 1.2uF 600
> 5.9 5.3
> 2.2uF 1210 Y5U 25 Tokin 1E225ZY5U-C203 7.5 69 2.0uF 210
> 7.8 7.4
> 2.2uF 1210 Y5V 25 Taiyo Yuden TMK325F225Z 3.6 23 1.7uF 1200
> 3.5 3.1
> 2.2uF 1210 Y5V 35 Taiyo Yuden TMK325F225ZH3 4.5 73 2.1uF 280
> 6.6 6.4
> 6.8uF 1210 Y5V 16 Taiyo Yuden EMK325F685Z 6.1 63 2.9uF 570
> 3.9 2.6
> 10uF 1210 Y5V 16 Taiyo Yuden EMK325F106Z 7.4 60 4.4uF 160
> 6.0 4.0
>
> 6.8nF 1808 X7R 1000 Kyocera 1808AC682KATMA 97.0 220 4.9nF 570
> 95.2 80.8
>
> 1.5uF 1812 Y5V 50 Taiyo Yuden UMK432F155Z 3.4 67 1.6uF 1400
> 3.4 3.5
> 3.3uF 1812 Y5V 25 Taiyo Yuden TMK432F335Z 4.2 72 2.7uF 1100
> 2.9 2.6
> 3.3uF 1812 Y5V 35 Taiyo Yuden TMK432F335ZG3 2.9 77 3.3uF 1100
> 2.6 2.6
> 4.7uF 1812 Y5U 25 Tokin 1E475ZY5U-C304 2.3 68 3.8uF 1100
> 2.5 2.2
> 4.7uF 1812 Y5V 25 Taiyo Yuden TMK432F475Z 3.2 75 3.3uF 980
> 2.8 2.3
> 4.7uF 1812 Y5V 35 Taiyo Yuden TMK432F475Z35 3.4 74 3.2uF 620
> 3.6 2.9
> 10uF 1812 Y5U 25 Tokin 1E106ZY5U-C304 1.7 75 6.9uF 1400
> 1.6 1.3
>
> 22uF 2220 Y5U 25 Tokin 1E226ZY5U-C505 1.7 74 12uF 970
> 1.5 1.1
>
> 10uF 3216 TANT 6.3 AVX TAJA106M006R 5.5 410 2.1uF 840
> 3.8 1.7
>
> 22uF 3528 TANT 6.3 AVX TAJB226M006R 2.9 130 4.5uF 1100
> 2.3 1.0
>
> 4.7uF 6032 TANT 35 AVX TAJC475M035R 4.2 99 1.1uF 1700
> 3.7 1.8
>
> 22pF radial 0.1x0.1 ceramic, 0.1 centers >500 250 23pF 2700
> 638.7 653.0
> 33pF radial 0.2x0.1 ceramic, 0.2 centers 340.0 210 31pF 7000
> 341.7 331.1
> 51pF radial 0.2x0.1 ceramic, 0.2 centers 290.0 140 51pF 6100
> 285.3 285.3
> 1.5nF radial 0.2x0.1 ceramic, 0.2 centers 50.0 27 1.6nF 6300
> 50.1 51.8
> 100nF radial 0.2x0.1 ceramic, 0.2 centers 6.1 30 76nF 9100
> 6.1 5.3
> 100nF radial 0.6 diameter, 0.3 centers 5.5 17 120nF 7300
> 5.4 5.9
> 1uF radial 0.3x0.4 ceramic, 0.2 centers 2.0 1 550nF 11000
> 2.0 1.5
>
>
>
> This is a small sample, even though it represents a couple of days in the lab,
> but it agrees at least in general with three assertions that I have read on the
> SI-LIST and EMC-PSTC mailing lists:
>
> 1. You should go for the smallest package you can.
>
> Answer: Seems to be true. ESL is usually lower in a smaller package with
> the same length:width ratio, but ESR showed no obvious pattern of changes.
> For a given length, a wider package will usually have a lower ESL.
>
> 2. You should go for the largest capacitance that you can get in a package.
>
> Answer: Seems to be true. ESL showed no obvious relation to capacitance,
> but ESR often dropped as the capacitance increased.
>
> 3. The dielectric does not affect ESR and ESL.
>
> Answer: Seems to be true until you reach/exceed the SRF. The impedance of
> C0G/NP0 capacitors then follows an inductive path, while X7R/Z5U/Y5U/Y5V
> capacitors wallow around near the ESR for a while then start rising slowly.
> This is probably good, because the lossy behavior will prevent sharp
> resonances that could cause unwanted peaks in the power-distribution
> network's impedance.
>
> I've been looking for but haven't found any other strong patterns between
> ESL/ESR and:
> * Capacitor value.
> * Package.
> * Dielectric.
> * Working voltage (WV).
>
> John Barnes Advisory
> Engineer
> Lexmark International
>
>
>
>
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