New 60 V Offset Power Rail Probes Offer the Capability Needed for 48 V Power Integrity Analysis

Figure 1. The RP2060 and RP4060
build on the legacy of the RP4030 power
rail probe. The new probes are ideally
suited to working with the new 48 Vdc 
power structures.

In 2016, Teledyne LeCroy first offered the RP4030 Power Rail Probe, which was designed to enable engineers to probe a low-impedance, low-voltage DC power/voltage rail signal without loading the device under test (DUT). It provided ±30 V of probe offset to allow a DC power/voltage rail signal to be displayed in the vertical center of the oscilloscope regardless of the gain (sensitivity) setting.

Recently, we released two, new power rail probes that build on those capabilities—the 2 GHz RP2060 and 4 GHz RP4060. Both probes feature:

• ±60 V Offset Capability
• ±800 mV Dynamic Range
• 50 kΩ DC Input Impedance (for low loading of low-impedance power rails)
• 1.2:1Attenuation (for low additive noise)
• MCX-terminated cable with a variety of board connections: 4 GHz*-rated MCX PCB mount;
  4 GHz* solder-in; 3 GHz* coaxial cable to U.FL PCB mount; optional 500 MHz browser
  

* Bandwidths listed are for the 4 GHz RP4060. Maximum bandwidth when used with RP2060 is 2 GHz.

Why the New Probes?

One driver of the new release is the increase in the number and size of data centers needed to support cloud computing and other data-intensive applications, and the new power architectures they require. The new rail probe is designed to ideally meet the needs of engineers working with power rails rated up to 48 Vdc.

Oscilloscope Serial Data Measurements and DAC: Trigger, Decode, Measure/Graph and Eye Diagram Software

Figure 1. Serial bus measurements made available
with "TDME" and "TDMP "decoder options.

All Teledyne LeCroy oscilloscopes support a rich set of standard waveform measurement parameters, but the installation of any "TDME" or "TDMP" serial decoder software option adds special parameters designed for measuring serial data buses. Besides automating the measurement of serial bus timing, these parameters allow you to access encoded serial data and extract it to analog values for what is essentially a Digital-to-Analog Converter (DAC)!

What’s in a Name?

Teledyne LeCroy has adopted the convention of using a key in the name of our serial trigger and decode products that tells you what capabilities they offer.  The “ME” or “MP” in the name of a Teledyne LeCroy serial decoder option (e.g., CAN FDbus TDME or USB4-SB TDMP) refers to "Measure/Graph and Eye Diagram" or "Measure/Graph and Physical Layer Tests." All these options include the following 10 serial bus measurements. Physical Layer Test options will also include measurements designed specifically to meet the requirements of the standard.

SDAIII and QualiPHY Software: Oscilloscope Eye Diagrams for Compliance and Debug

Figure 1. SDAIII enables eye diagrams and eye
measurements of four lanes of  streaming data.

Besides the serial TDME and TDMP options discussed earlier, there are other ways to generate eye diagrams on your Teledyne LeCroy oscilloscope for compliance testing and debug.

SDAIII Serial Data Analysis Software

SDAIII offers the most comprehensive eye diagram capabilities for Teledyne LeCroy oscilloscopes, with tools for optimizing the displayed eye that are especially useful to high-speed serial data analysis.

Serial Trigger, Decode, Measure/Graph & Eye Diagram (TDME) Software: Oscilloscope Eye Diagrams for Debug

Figure 1. Two eye diagrams generated from 
three active USB serial decoders.
Click any image to enlarge it.

The eye diagram is a general-purpose tool for analyzing the signal integrity of serial digital communications signals. It shows the effects of additive vertical noise, horizontal jitter, duty cycle distortion, inter-symbol interference, and crosstalk on a serial data stream. The vertical opening of the eye is affected by these elements, as well as gain differences between devices on the bus, so that the more problems with signal integrity, the more “sleepy” the eye appears. A wide open eye is indicative of good signal integrity.

It is commonplace to use an oscilloscope with decoder software to analyze the health of serial data streams, where the combination of the electrical waveform and the link layer decoding shows if and where the protocol breaks down at the physical layer, but an eye diagram can better show the degree of signal interference that may be impacting the serial logic—especially if it could be generated for particular devices or packets.

Oscilloscope Testing of 10Base-T1S Automotive Ethernet Signal Integrity

Figure 1. The 10Base-T1S TDME option features
easy eye diagram creation for signal integrity analysis.
Click on any image to enlarge it.

In addition to special serial data bus measurements of 10Base-T1S signals, the 10Base-T1S Trigger, Decode, Measure/Graph & Eye Diagram (TDME) option automates the generation and display of eye diagrams on Teledyne LeCroy oscilloscopes. Eye diagrams are an important element of serial data analysis, used to understand the signal integrity of the communications network. 

The eye diagram is a general-purpose tool for analyzing serial digital communications signals. It shows the effects of additive vertical noise, horizontal jitter, duty cycle distortion, inter-symbol interference, and crosstalk on a serial data stream. 

The eye diagram is formed by overlaying repetitive occurrences of slightly more than a single clock period (UI) of a serial data signal on a persistence display which shows the accumulated history of multiple acquisitions, as shown in Figure 1.

Due to the use of Differential Manchester encoding (DME), the 10Base-T1S eye is formed with twice the signal clock rate. The signal shown has a symbol rate of 12.5 Mbps and the eye is clocked at 25 Mbps. 

Oscilloscope Measurements of 10Base-T1S Automotive Ethernet PLCA Cycle Timing

Figure 1. Color-coded decoding of 10Base-T1S
stream makes it easy to measure timing between
signal elements. Click on any image to enlarge.

The 10Base-T1S Trigger-Decode (TD) and 10Base-T1S Trigger, Decode, Measure/Graph & Eye Diagram (TDME) options enable Teledyne LeCroy oscilloscope users to trigger on and decode Ethernet control and payload data from 10Base-T1S Automotive Ethernet signals. The decoding is color-coded to provide fast, intuitive understanding of the relationship between message frames and other time-synchronous events. Knowing the location of the various protocol elements makes it easy to measure Physical Layer Collision Avoidance (PLCA) cycle timing using either standard oscilloscope tools, or special serial bus measurements included with the TDME options.

PLCA cycle timing is measured to assure interoperability of the attached nodes in a 10Base-T1S mixed-segment, multidrop bus. This class of tests measures the timing between events on the bus relative to a specific bus event, usually the BEACON signal initiated by the Master node. 

Let’s look at a simple example of a 10Base-T1S network with two nodes, the Master (Node 0) and a device (Node 3). The acquired waveform is shown in Figure 2, decoded using the 10Base-T1S TDME option. The top grid shows the complete acquisition, which consists mostly of BEACON signals over a record of twenty-five million samples. Toward the end of the acquisition are two packets from the other nodes. The table at the bottom of the screen lists all the elements decoded in the full acquisition.

Isolated Oscilloscope Inputs vs. Isolated Oscilloscope Probes

Some users in high-voltage test environments seek measuring instruments with isolated inputs because they want the safety and convenience of isolation without having to spend money on an isolated oscilloscope probe, like the Teledyne LeCroy DL-ISO or the Tektronix IsoVu®. While that's understandable, isolated inputs built into the instrument channel may be convenient, but they don't necessarily give you good performance, certainly not as good as  you would get from a high quality, high-voltage isolated probe.

Figure 1. Cascaded H-bridge signals captured using an isolated input (left) and an isolated probe (right).