Keithley 2450 SourceMeter  Review  - Page 1
Forum section: electronics / testgear

author: robrenz
author_rank: Super Contributor
timestamp: November 14, 2013, 02:13:27 pm
content: This is the link to Part 1 of myreview of the Keithley 2450 SourceMeter.on the Element14 Road Test site . This is theEEVBforum threadon how I got this thing of beauty. The video has segment headers that match the Road test review topics. Part 1 only covers general impressions and exploring the touch screen interface. Part 2 will be some performance comparisons and functionality of the unit when used a Graphing Voltmeter, Ammeter, Ohmmeter, Power supply, and E-load.

author: quarks
author_rank: Frequent Contributor
timestamp: November 14, 2013, 02:28:19 pm
content: great, will watch it asap

author: sprocket
author_rank: Regular Contributor
timestamp: November 14, 2013, 02:32:06 pm
content: Droool.. Add a beer tab and some boobs and it would be perfect O0

author: StubbornGreek
author_rank: Frequent Contributor
timestamp: November 14, 2013, 09:39:36 pm
content: Fantastic for a first impressions - looking forward to part 2. Do you plan on taking her apart for a guts shot?

author: Wytnucls
author_rank: Super Contributor
timestamp: November 14, 2013, 10:06:34 pm
content: Great revue Robrenz. I'm glad you finally got one of the meters on offer.

author: BravoV
author_rank: Super Contributor
timestamp: November 15, 2013, 02:12:27 am
content: Love the review, thanks !Can only drool while watching it.Btw, just curious if that > 5 grands of meter only came with that pair of probes ? No other bell & whistles probes like for 4 wires kelvin type ?

author: robrenz
author_rank: Super Contributor
timestamp: November 15, 2013, 03:03:17 am
content: Thanks everyone,@BravoV Nope, that's all you get but I think that is typical for this level of instrument. This is a very high performance wide range 4 quadrant programmable power supply also, not just a 6.5 digit graphing and datalogging meter. take a look at the specs on the 2450 data sheet link below.Excerpt from the Element14 review:Although an expensive piece of gear at ?$5400.00 it could be argued that it might be a less expensive more integrated alternative to the separate instruments it can function as:• 6.5 digit DC voltmeter with 10nV resolution and >10Gohm input impedance• Picoammeter with 10fA resolution and a < 100µV burden voltage on all ranges• 20W Precision current/voltage source/sink with 500fA and 500nVresolution (100mA at 200V and 1A at 20V)• Precision 20W electronic load.• 6.5 digit Ohmmeter with 1µ? resolution and >200G?.• Flexible real time graphing/data logging and extensive standalone programmability.• Semiconductor curve tracer.• Leakage testerHere are some links to additional information:Electrical specifications2450 Data sheetKeithley’s What is a SMU?General overview videoKeithley 2450 product tour VideoComparingSMU vs power supplyComparingSMU vs DMMThe greatKeithley Low Level Measurement Handbook PDF.Great resource on intricacies of SMU applicationsAgilent Parametric measurement handbook PDF

author: BravoV
author_rank: Super Contributor
timestamp: November 15, 2013, 03:10:03 am
content: For sure, now all your precision PSUs have a great guardian that guarding their accuracy at anytime, does this mean more precision PSUs to come ?

author: robrenz
author_rank: Super Contributor
timestamp: November 15, 2013, 03:32:20 am
content: You will be happy to hear that your 6115A (if in cal.) at 100V is more accurate than the 2450

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: November 15, 2013, 11:59:17 pm
content: Hi,This Keithley SMU looks remarkably similar to the Agilent B2900 series of SMU.Link:http://www.home.agilent.com/en/pd-1983568-pn-B2901A/precision-source-measure-unit-1-ch-100-fa-210-v-3-a-dc-105-a-pulse?nid=-33504.978794&cc=CA&lc=engJay_Diddy_B

author: robrenz
author_rank: Super Contributor
timestamp: November 16, 2013, 01:37:17 am
content: Maybe Agilent should send me one of those so I could report on which one I like betterI did look at the specs on that unit and compared to the 2450 and as usual each has things it does better than the other. They are definitely competitors and the Agilent is 15W higher power and has AWG like features the starting price is $500.00 more than the Keithley.

author: TiN
author_rank: Super Contributor
timestamp: January 04, 2014, 09:30:02 pm
content: No teardown?

author: robrenz
author_rank: Super Contributor
timestamp: January 07, 2014, 07:16:51 pm
content: Part 2 is added on the end of the original part 1. Scroll down till you see the part 2 header. The Element14 editor trashed the photos of part 1 when I added part 2.Part 2 is here now on reply# 15

author: plesa
author_rank: Frequent Contributor
timestamp: January 15, 2014, 01:13:07 am
content: Quote from: robrenz on November 16, 2013, 01:37:17 amThe Agilent SMU does not have the triax connection, which is for such a low level measurement critical. They offer banana to triax adaptorhttps://www.eevblog.com/forum/Smileys/default/icon_thumbsdown.gifQuote from: TiN on January 04, 2014, 09:30:02 pmWhat about teardown photos of 2636B? There is nothng important, it is so dense, without dissassembling into pieces you will see nothing.It consist from two modules and power supply.

author: EEVblog
author_rank: Unknown
timestamp: January 15, 2014, 01:14:49 am
content: I'm so jealous!I so want one of these babies...

author: robrenz
author_rank: Super Contributor
timestamp: January 15, 2014, 02:16:13 am
content: Part 2 posted here where it will get some viewsThis will cover the 2450 as a Power supply, Voltmeter, Ammeter, and Ohmmeter. I show how the 2450 specifications compare with the Agilent B2901A SMU, my Fluke 8846A and my IET LOM510A micro-Ohmeter. The last two are the only calibrated instruments I have to do accuracy comparisons with. The Agilent B2901A is a close match at $500.00 more than the 2450 and is higher performance in several areas but is less accurate on paper. All the specs have been charted in a way that graphically show where each instrument is most accurate. The measurement comparison charts have a spec ratio column that show which instrument should be the reference and how much more accurate it is. I include the ancient HP6115A power supply in the power supply testing since its specs are very close to the 2450 and even better in some parts of the ranges. This 6115 is as received from fleabay with its last calibration in 1992. There are lots of things a metrologist would pick apart about my comparisons but I am just trying to give a general feel about how this unit performs. 2450 readings were done at 10NPLC and a repeat filter of 10 and then stat average using the number of readings show on each chart. The 8846A was set for 100NPLC and a stat average of the number of readings show on each chart. This was done to minimize noise and give stable readings at these high resolutions. 8846A accuracy is the same on 10 and 100NPLCI have used the touch screen even more in doing this testing and I really love this interface. I can’t think of a more efficient system for entering settings. The milli, micro, nano, x10, and /10 buttons on the input screen are absolutely brilliant. I have found I rarely want to use the navigation knob even though it works well. This screen pops up for both voltage and current settings/limits.Use as a power supply in Voltage mode and as a Voltmeter:This is the stat screen of sourcing 1mV for 101 readings (roughly 6 mins). Notice the 10nV resolution and a span of 170nV and SD of 31nV. This is pretty good stability in my book.This is the stat screen of shorted input and zeroed with relative function for 658 readings (roughly 36 mins). Notice the span of 210nV and SD of 37nV. Only slightly higher span and SD than the 6 mins above.This is the response of changing the voltage value from 1V to 5V and back to 1V with no load. Nicely behavedThis is the output switch on and off with a 5V setting. Also well behaved. Notice the approximately twice as fast rise time compared to the voltage change above.Some points on all the spec charting:These are plots of the 1 year specs of maximum error as apercent of the measured value. This puts all specs on an even playing field for comparison. The jagged data jumps are the natural effect of (% of reading + offset or % of range) at the range changes where percentage and/or offset values may be different. The other subtle data kinks are the effect of the value data not being the same step in value from decade to decade. What appear to be discontinuities of data from one chart edge to the next is a range jump happening right on the chart edge.The SMU’s are very close and better than the 6115A in this range. The 8846A is over 40x more accurate than the other instruments in this range up to 10mV and progresses to 2.2x more accurate at the 200V level. This makes it the reference for all measurements in all ranges on the voltage testing. Unfortunately it won’t be that clear cut on current and resistance comparisons.The 2450 and the 6115A are significantly more accurate than the 2901A in the 2 to 20V range.The 2450 and the 6115A are significantly more accurate than the 2901A in the 20 to 200V range. The 6115A even beats the 2450 measure spec in the 20 to 80V range.A little guidance on this mess. All the blue columns are 1 year specs in ±volts for each value. The yellow column is how much more accurate the 8846A is compared to the 2450 measure for each value. The light green columns show how much percentage of the spec is used if the 8846A had no error. To go to the other extreme, in the magenta column I ignore the extremely good 8846A Cal. data and add the full 8846A spec error to the instrument error and use that to calculate the worst case percentage of spec used. In both cases the percentage of spec used is impressively low. The 6115A was last calibrated in 1992 and is still in spec (also very impressive). I used 2 short coax cables with 4 coax to male banana adapters to connect with remote sense right at the 8846 input terminals. I think the outer shields of the coax being connected to the 8846A measurement common helped the noise be lower than using 4 independent banana jumpers.Use as a power supply in Current mode and as an Ammeter:This is a stat screen of sourcing zero current thru Force high and Force low triax cables that are connected at one end The measure reading was zeroed out using relative. A span of 110fA and a SD of 19.7fA over 62 readings is amazing. You can’t get here without the triax and driven guarding of the rear terminals.With current things get a little more complicated. The 8846A is only equal or more accurate in the 1A to 100mA range. After that the 2450 is progressively more accurate as the measurements get lower. At 10nA and below the 2450 is approximately 500X more accurate than the 8846A. Another area where the 2450 excels in current measurement is its very low burden voltage of ?100µV on all ranges.Clearly the 2450 excells here and is more accurate than the 2901A in the 110pV thru 1A range. The 2901A does not have separate source and measure accuracies. On the 2450 with source readback on, the sourced value is measured at measurement spec accuracies before it displayed and used in any calculations such as resistance or wattage measurements. This is an example of how difficult spec comparison would be without this chart style. Look at how the 2450 source and 8846A 10NPLC cross over each other multiple times on which is more accurate.The color coding here and chart explanation is the same as the similar Voltage chart above. This is the accuracy measurements where the 8846A is the reference. Obviously you have to take the spec ratio into account as to how much weight you give to specific values. This was done with Force high and Force low triax cables directly feeding the 8846A in current mode. Considering the last Cal data of the 8846A it is reasonable to use the “error as percent of spec assuming no error on the 8846A” column as a general measure of accuracy. Very nice results with a high of only using 8.6% of the allowable spec. Even if you use the magenta worst case column it is still well within spec.These are the accuracy measurements where the 2450 is the reference. Again you have to take the spec ratio into account as to how much weight you give to specific values. But the 2450 is clearly the reference here. The 1.2 and 1.3 ratios seem to be anomalies but they are cause by the 8846A having 20% over range where the 2450 has a 5% over range. This is most noticeable where the spec ratio is less than 1.5 but exists in all the ratios. The offset or % of range part of the specs has the least effect at the top of the ranges. The measurements at 100nA and below were done with both the 8846A and 2450 offset currents removed with relative or zero. The 2450 worst case source error as a percent of spec is all within tolerance even when adding the full measure spec error to the measured value. The 8846A also does very well with very low percentage of spec numbers especially below 100µA.Use as an Ohmmeter:Quickset gets you to ohmmeter and allows setting 4 wire mode. For maximum accuracy source readback needs to be on and offset compensation needs to be on for low resistances to minimize the effects of thermal emf’s. This chart shows the LOM510 is clearly the reference for 2 ohms and below. The 2450 has better resistance specs than the 2901A in all ranges.Here we see the 8846A is clearly the reference from 20 Ohm to 10M OhmAll the 2450 resistance measurements were done using using full 4 wire triax kelvin connections to the resistances. Source readback was enabled along with offset compensation. The <2? values were done sourcing 1 amp. The 8846A was also 4 wire kelvin connections and offset compensation on the low values using my offset compensated ohms adapter. The IET LOM510A is 4 wire kelvin connections and used the offset compensated ohms mode. The resistances from .1? to 20M? were my .1% decade box. The three lowest resistances was a piece of wire with the sense connection spacing adjusted to give the nominal value as measured by the LOM510A. The spec ratio of the LOM510A on these values is certainly high enough for this to be a valid method. My connection system allowed me to connect each instrument to the setup without disturbing the exact spacing of the 4 kelvin clips. This chart is strictly a general comparison using the best spec instrument as the reference for the relative accuracy of the other two. The best spec instrument is dark blue background with the second best spec instrument in light blue background and the worst spec instrument with no background. All I can say here is all the instruments agree pretty closely and generally do much better than their one year spec. I finally realized the 2450 has a fan that kicked in when sourcing the 1A on the low resistances. It’s audible tone says variable speed and its seems to track the demand closely.Conclusion:I am very impressed with the 2450 performance and ease of use. Entering or changing values is really nice and very quick. The graphing capabilities are very useful as is and I believe will be improved even more with the next firmware release. Even if you could buy separate programmable instruments of equal resolution and accuracy for the same money, I don’t see how it could be as effective as the 2450 with all the built in integration of source, measure and graphing. Since complete test routines can reside on the 2450 it can be a stand alone test and measure unit that can even control external equipment such as binning of components. If you don’t use a SMU for a living there is a lot to learn to really be aware of all the capabilities that are packed into this unit (I am not there yet!). The setup scripts are an important tool to have correct repeatable setups. There are a lot of variables to be set for both source and measure and they don’t get remembered when you turn the unit off unless you store them as scripts and reload them from the usb. This will probably be my most used instrument on the bench because of its extreme versatility.I will post a video link of general use functionality of all the above source and measure functions in the next couple of weeks,

author: EEVblog
author_rank: Unknown
timestamp: January 15, 2014, 02:20:20 am
content: I don't even want to know how long it took you to do that review!, but in any case, Keithley well and truly got their monies worth. Nice one.

author: robrenz
author_rank: Super Contributor
timestamp: January 15, 2014, 02:59:08 am
content: Thanks Dave, that means a lot to me coming from you.

author: quarks
author_rank: Frequent Contributor
timestamp: January 15, 2014, 03:41:30 am
content: Great work

author: ChrisGammell
author_rank: Unknown
timestamp: January 15, 2014, 05:15:26 am
content: I agree, that was really quite a killer review and comparison. I do believe I'll forward that on to the guys I know there (including the designer) :-)

author: BravoV
author_rank: Super Contributor
timestamp: January 15, 2014, 07:43:12 am
content: Thank you Robrenz, really good review !For sure, you deserved that 5000 bucks piece of equipment, and after reading these wonderful report, personally I'm really glad & proud but jealousat the same time that Keithley choose you.A bit OOT if you don't mind, assuming the 6115A is calibrated, did it's accuracy drifted much from it's original spec when you received for the 1st time ?One thing for sure, this review have made me to love my precious 6115A even more.

author: dr.diesel
author_rank: Super Contributor
timestamp: January 15, 2014, 11:09:11 am
content: Quote from: robrenz on January 15, 2014, 02:16:13 amHoly hell, SOB, great work.

author: robrenz
author_rank: Super Contributor
timestamp: January 15, 2014, 03:21:33 pm
content: Thanks all for your kind words@ ChrisGammellJohn Tucker the project manager for the 2450 contacted me after my barrage of firmware bug finds and many improvement suggestions. I have heard that some of my suggestions will be in the next firmware release. He also requested (and received) the spreadsheets of all the data that I posted.@ BravoVI have not touched that 6115A yet. That is as received from fleabay with a 1992 cal. sticker still in place. It would certainly be even better with a fresh cal.

author: robrenz
author_rank: Super Contributor
timestamp: February 21, 2014, 01:23:58 pm
content: I just got a pre release version of the 2450 firmware update and installed it last night. Wow, they really cleaned up and improved the graph screen functionality. I have not had time to check if all my suggestions/ bugs were addressed but it is like a whole new machine. The screen gestures now behave like you would expect and you don't get any bogus graphing.I will post a video of what was addressed when I get a chance. (real busy with real work at the moment)

author: pgross
author_rank: Contributor
timestamp: February 21, 2014, 03:09:26 pm
content: Hi robrenz,Thanks a lot for your effort to post this very comprehensive and informative review.Now we'll just have to wait for the price to come down....One thing missing though is an "easter egg" - a Teardown feature on the instrument, where hi-res pictures of theinnards shows up on the screen - preventing the user to break the calibration seal/Peter