Busses, serial links and required scope bandwidth - Page 1
Forum section: electronics / testgear

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: February 19, 2016, 09:05:27 am
content: Quite often the question arises what oscilloscope bandwidth is required to probe a certain bus or serial interface, so in a moment of boredom I assembled the following table from various sources.Please keep in mind that this list shows the bandwidth required to examine the signal integrity. Decoding often works with less bandwidth, although it may be unreliable/erroneous as with insufficient bandwidth the waveform on the screen hasn't much in common with how the real signal looks like.StandardBit RateMinimum Bandwidth req'dEthernet 100BT125Mbps500MHzEthernet250Mbps1GHzFibre Channel 50MB/s531.25Mbps1.5GHzUSB2 Super-Speed480Mbps2GHzIEEE1394b Firewire 800786.43Mbps2GHzRapidIO LP-LVDS1Gbps2.5GHzFibre Channel 1GFC1.0625Gbps2.5GHzDDR2-800800MTps3.5GHzEthernet 1000BT1.25Gbps3.5GHzIOF1.24416Gbps3.5GHzRapidIO LP-LVDS1.25Gbps3.5GHzRapidIO LP-LVDS1.5Gbps4GHzSATA (SATA150)1.5Gbps4GHzIEEE1394b Firewire 16001.5729Gbps4GHzDVI1.65Gbps4GHzHDMI 1.2a1.65Gbps4GHzRapidIO LP-LVDS2Gbps/2.5Gbps6GHzPCI Express 1.x2.5Gbps6GHzDDR3-16001.6GTps8GHzExpressCard2.5Gbps8GHzInfiniBand2.5Gbps8GHzRapidIO LP-LVDS3.125Gbps8GHzDisplayPort 1.12.7Gbps8GHzHyperTransport 2.02.8Gbps8GHzSAS 1.0/1.13Gbps8GHzSGMII3.125Gbps8GHzXAUI3.125Gbps8GHzFirewire3.2Gbps8GHzDDR44GTps10GHzHDMI 1.3b3.4Gbps10GHzSATA2 (SATA300)3Gbps10GHzFibre Channel 4GFC4.25Gbps13GHzSerial RapidIO4.25Gbps/5Gbps13GHzInfiniBand5Gbps13GHzPCI Express Gen25Gbps13GHzPCI Express Gen38Gbps13GHzHyperTransport 3.05.2Gbps13GHzUSB 3.05Gbps13GHzDisplayPort 1.25.4Gbps16GHzGDDR56Gbps16GHzSAS26Gbps16GHzSATA3 (SATA600)6Gbps16GHzSerial RapidIO6.25Gbps16GHzHyperTransport 3.16.4Gbps16GHzQPI6.4Gbps16GHz10GBT10.3125Gbps20GHzSFI/SFP+10.3125Gbps20GHzCEI-1111Gbps25GHzSAS312Gbps25GHzInfiniBand25.78125Gbps50GHzCEI-25/2825Gbps/28Gbps60GHzI'll try to update the table from time to time.

author: ADT123
author_rank: Regular Contributor
timestamp: February 19, 2016, 10:21:35 am
content: Thanks for the useful table - perhaps its worth pointing out that the bandwidth requirements for decoding serial data are different from making signal integrity measurements?Take the 250Mbps Ethernet below - you can think of that as a 125MHz square wave signal in terms of frequency. 1GHz is a sensible bandwidth for signal integrity but 500MHz would be more than enough if you are more interested in decoding the data.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: February 19, 2016, 10:31:14 am
content: Quote from: ADT123 on February 19, 2016, 10:21:35 amThanks for bringing this up. I've updated the original post to reflect that.

author: awallin
author_rank: Frequent Contributor
timestamp: February 19, 2016, 03:03:41 pm
content: That's kind of depressing from a hobby-budget-scope point of viewPerhaps a list of what you *can* do with a 100MHz or 300MHz scope would be more uplifting?

author: Skimask
author_rank: Super Contributor
timestamp: February 19, 2016, 03:09:29 pm
content: Quote from: awallin on February 19, 2016, 03:03:41 pm<list>1. A 56K modem...on a good day.</list>

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: February 19, 2016, 03:11:16 pm
content: Quote from: awallin on February 19, 2016, 03:03:41 pmWell, it would be a whole lot shorterBut yeah, low bandwidth scopes simply don't cut it for modern high speed busses. Which I know must be depressing, as people sometimes ask for a suitable entry level scope for doing USB or Ethernet stuff. Unfortunately that's not gonna happen, even USB2 is already lower high-end territory.And then there's the question of probing...

author: tmbinc
author_rank: Frequent Contributor
timestamp: February 20, 2016, 06:33:11 pm
content: I've successfully decoded PCIe Gen1 on my (bandwidth-hacked) Tek DPO5034, so don't panic.

author: Fungus
author_rank: Super Contributor
timestamp: February 20, 2016, 06:38:25 pm
content: Quote from: awallin on February 19, 2016, 03:03:41 pmSPI, I2C, RS232...(Weirdly enough that's a list of the protocols that are in the menu of my 'scope)

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: February 21, 2016, 01:09:31 am
content: Quote from: tmbinc on February 20, 2016, 06:33:11 pmDecode of PCIe 1.x can work with a 2GHz scope, but that's pretty much it.It always stroke me as odd that Tek offered PCIe Serial Analysis on a scope series that doesn't even have sufficient bandwidth that's required for it (the DPO5k only goes to 2GHz).

author: Keysight DanielBogdanoff
author_rank: Unknown
timestamp: February 22, 2016, 06:47:09 pm
content: Quote from: Fungus on February 20, 2016, 06:38:25 pmOur InfiniiVision scopes support I2C, SPI, UART (RS232,485, etc), CAN (-dbc), LIN, FlexRay (lol), I2S, MIL-STD1553, ARINC429, SENTSo there's quite a bit you can do with the lower bandwidth scopes. But once you start getting into high speed digital you're going to have to upgrade. The list from Wuerstchenhund is (AFAIK) more industry focused and less hobbyist focused.

author: Keysight DanielBogdanoff
author_rank: Unknown
timestamp: February 22, 2016, 06:53:37 pm
content: Slide 49 on page 25 is a good reference for this, too.http://www.keysight.com/upload/cmc_upload/All/Oscilloscope_BW_Reqmts_for_Emerging_Serial_Data_Intfcs.pdfFrom an older but interesting talk on optimizing your bandwidth.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: February 23, 2016, 06:39:41 am
content: Quote from: Keysight_DanielBogdanoff on February 22, 2016, 06:53:37 pmThanks for the link, I've added DDR2 and DDR3 to the list.Funny that it lists SAS 1.5Gbps, as this never was a real standard (SAS Generation 1 is 3Gbps).QuoteWell, actually itisaimed at hobbyistsThese days quite often even hobbyists want to look at stuff like USB2/3, DDR2 and HDMI, and on occasion someone asks for a cheap entry level scope recommendation to do that. The list is meant to be as a guide to show that even measly USB 2.0 is pretty much out of reach of any entry-level (and mid-range) scope (and essentially anything that carries the Rigol logo).

author: ANTALIFE
author_rank: Frequent Contributor
timestamp: March 20, 2022, 12:45:42 am
content: Thanks heaps for creating this list!!!

author: pdenisowski
author_rank: Super Contributor
timestamp: March 20, 2022, 03:06:02 am
content: Quote from: Keysight DanielBogdanoff on February 22, 2016, 06:47:09 pmAnd the Rohde and Schwarz RTM and RTA oscilloscopes also support all of these decodes ... just saying ....https://scdn.rohde-schwarz.com/ur/pws/dl_downloads/dl_common_library/dl_brochures_and_datasheets/pdf_1/Option_sheet_-_RTx-K1_-K2_-K3_-K5_-K6_-K7_serial_protocol_triggering_and_decoding_v1.10.pdf

author: tautech
author_rank: Super Contributor
timestamp: March 20, 2022, 05:26:01 am
content: So much has changed in just 6 years since this thread was last active where now even some relatively cheap scopes support I2C, SPI, UART, CAN, LIN (Standard) and CAN FD, FlexRay, I2S, MIL-STD-1553B, SENT, and Manchester.

author: nctnico
author_rank: Super Contributor
timestamp: March 20, 2022, 12:04:36 pm
content: Sales people picking a fight. -ding ding- round one