Tektronix 6-Series Analysis and Extrapolations on the Design - Page 1
Forum section: electronics / testgear

author: Proto
author_rank: Contributor
timestamp: August 20, 2018, 07:28:33 am
content: Personal IntroPersonal Intro• Worked in computer chip sales for most of my career• Started in Application Engineering• Last worked in engineering management for wireless technologies in smartphones• Transitioning to full-time R&D business• Scope nerd• Detail orientedTek’s Need for Product between 2 and 8 GHz• Tek 7000 Series getting stale and covers through 3.5GHz only• Tek 70000 Series starts at 4GHz; goes to 33GHz and has “contact us” for pricing• Keysight S-Series spans 500MHz to 8GHz so Tek 6-Series overlap is clearFlexChannel Discussion1. Acknowledge concern with loss of dedicated logic probe port2. Customers still purchase scopes without digital channels – some of these have no after sale option to add them; what if your needs change?3. What are you designing / debugging with greater than 8 and fewer than 16 digital channels up to ~500MHz?4. What if you need >16 Logic probe channels?5. If Tek made a 12-bit digital FlexChannel probe, would you be less concerned about not having a dedicated port?6. With Tek 5 Series, what if you need > 4 or > 6 analog channels7. Logic probes cover a sweet spot relative to modern bus evolution – too slow for many parallel and serial buses; when fast enough, Logic probes preserve analog channels for where they are needed8. Lots of GHz-class, industry-standard serial buses in use today to reduce power and routing space (versus parallel) while maintaining application specific transfer rates; add lanes to increase throughput but way too fast for Logic probes in general9. Serial Buses – I2C. SPI, RS232, CAN, I2S, MIPI DSI, MIPI CSI, USB1.0, USB 2.0, USB3.0, USB3.1, HDMI, DisplayPort, SATA, video capture buses (bold items are a fit for Logic probe use)10. Parallel Buses – memory, graphics controllers, on slow systems; else way too fast for Logic probes11. Nobody has a crystal ball into all application needs but suppliers have more data than users12. Reduces product permutations - BW, Channels, Mixed Signal/Non-Mixed Signal13. Keysight DSOX/MSOX 4000 – 16 variants14. Keysight DSOX/MSOX 6000 – 4 base variants, 12 combos of BW and Logic probe upgrades15. Tek MDO3000/MDO4000 – 9 variants16. Tek MDO4000C -17. Substitute 8 logic channels for single analog channels and reserve the latter for enhanced signal inspection when high bandwidth is required18. Also look at other ways to view wide, slow data. If within programmatic flow, try to send via debug SPI function (8, 16, 24 bits or more) and decode with serial protocol upgrade packageFull-speed scope mainframe runs at 8GHz with single mainboard / physical instrument design• First for Tek?• Aftermarket speed upgrade to unlock higher bandwidth• Keysight has done this for S-Series and DSOX/MSOX 6000 Series6-Series is designed for 6 FlexChannels (Note: I have NO window into Tek’s product plans!)• Review video with heat exchangers in the still frame• Provision for 3 TEK061 preamps per A/D is included (6 total) in mainboard layout (4 are placed)• Subpanel and shields are ready for 2 additional FlexChannels and preamps• The additional FlexChannels fit in the wide space between the existing pairs• Would not anticipate an aftermarket upgrade by user• Full 8-channel version would cause high bandwidth model pricing to be excessive (6-ch could exceed $100K; 8-channel even more!)• Tek could potentially add a dedicated 16-channel logic probe port to a 4 or 6-FlexChannel 6-Series based on information extrapolated and certainly not mentioned per se in the video referenced aboveFlexChannel logic probe interface might accommodate 12-bits or more• Contains 26 contacts in addition to TEKVPI legacy connections• Hypothetically there is potential for 12 signals with interspersed grounds and 2 spares for power and/or control• 12-bits is a natural fit since A/D also generates 12 -bits to memory store• Logic probe channels are sampled at full rate, but speed path is < 500MHz – might require an adaptation at peak acquisition rateImplementation insights• 6-channel ready - Once again, Tek didn’t try to hide provisions for 6 channels which are in plain sight• 2x 100GS/s A/D converters? Tek video mentions aggregate of 100GS/s – not sure if this is per converter or per mainframe but it seems to be the former, therefore, up to 4 preamps per A/D as 2 A/D’s are visible though only 3 preamps can be routed with current mainboardAcquisition Memory• 62.5Mpts standard• 125Mpts is very low-cost ($1250) upgrade – I would guess 125Mpts is unlocked by software and ships standard with only 62.5Mpts accessibleReduction to 8-bits at 25GS/s; may incorporate two-step flash (parallel) converter• 8-bits in first step, 4 bits in second step performed serially• 40pS for 8-bit conversion• Plus, another 40pS for 4-bit conversion – gets you to 12.5GS/s (80pS overall conversion time)• Optimizes comparator count (256 for 8-bit flash conversion and 16 for subsequent 4-bit conversion versus 4096 for one pass 12-bit conversion• Noise at input frequencies of interest for max acquisition rate trends higher leading to lower effective number of bits (ENOB) in conversion process (higher total error component spanning several low order bits is to be expected)• Note: 6 Series uses Hi-Res mode to average samples post conversion and stretch resolution from 12-bit up to 16-bits with acquisition speed reductions increasing as the resolution increases• LeCroy HD Series maintains 12-bit resolution via A/D up to 20GS/s (the limit) but usability drops to 2 channels, else run 4 channels at 10GS/s.• Tek 6-Series reduces resolution to 8-bits but maintains sample rate to 25GS/s across all 4 channels, a very natural fit• Keysight and LeCroy A/D’s often drop support to half the number of physical channels at highest acquisition rates

author: Proto
author_rank: Contributor
timestamp: August 25, 2018, 06:22:46 pm
content: Link to Tektronix Video (The Science of Low Noise) with engineers discussing the designhttps://www.tek.com/case-study/science-behind-low-noise• Still video capture JPEGs from the video follow to show 6-channel internal architecture• Subpanel design is common to 5 and 6-Series; 8 total channel positions are clearly shown with two located between the exposed FlexChannels for the current 6-Series design• Photo with BNC connectors further shows 4 fully functional channel positions and 2 additional channels in the middle for possible future use• Back side of 6-Series mainboard depicts shielding for 6 channels with Tek061 preamps visible on left side. The 6-Series mainboard appears to be routed for 6 channels as part of its basic design.• Tek061 differential outputs route to one of 2 ASICs (w/A/D internally) for the whole platform. Each is capable of 100 GS/s so Tek could have used just one for 4 channels. The use of two ASICs offers 8-channel capacity so 6 FlexChannel-ready mainboard layout channels simplifies manufacturing.• Another possibility for the 6-Series is to add Logic-only, non-FlexChannel inputs on the outer flanks of the 8-channel-ready subpanel mechanical design. These could be added to the current 4-FlexChannel model or a future 6-Flexchannel model and should not require TEK061 preamps.• The last point presumes using the existing TLP058 FlexChannel logic probes-only with the outermost left and right-side connectors (positions 1 and. Also assumed is that Logic Probe digital signals route to the ASIC. Users would get back their dedicated 16 digital channels. As mentioned in the first post, a 6-Series with 8 FlexChannels would be very pricey at higher bandwidths. A 6 + 2 helps stem price escalation by having a 6 FlexChannel + 2 Logic probe channel 6-Series compared to 8 FlexChannels that would need to carry the analog bandwidth for all connector positions and dedicated TEK061 preamps.• Bottom line, Tektronix has many options for designing future members of the 6-Series family.