Scope front-end chip
90000 X-Series scope
Sporting real-time bandwidths of up to 32 GHz, Agilent’s Infiniium 90000 X-Series oscilloscopes set a high-water mark for true analog bandwidth that promises to meet the needs of engineers working with emerging wireline communication standards, high-speed serial data links such as USB, SAS, or PCI Express, or high-energy physics (click here for a video demonstration).
Alongside the unprecedented bandwidths, the series offers up to 2 Gpoints of memory and a maximum sampling rate of 80 Gsamples/s. There are 10 models in the series with bandwidths of 16, 20, 25, 28, and 32 GHz.
Accuracy in jitter measurements at high speeds requires a scope that offers both high bandwidth and a low noise floor. The 90000 X-Series scopes offer an industry-low jitter measurement floor of about 180 fs as well as the lowest noise floor (2 mV at 50 mV/division, 32 GHz).
One element of the “secret sauce” that gives these scopes their capabilities is Agilent’s investment in a proprietary indium-phosphide (InP) process technology optimized for RF and high-performance scopes. The scopes’ front-end chips, which are fabricated on that process, are packaged in a multi-chip module (Fig. 1) where they’re embedded inside a substrate for improved shielding and grounding. Packaging the front end in this fashion also minimizes wirebond lengths, which in turn minimizes inductances and helps to hold down the noise floor.
The front end includes two new preamplifiers rated to 32 GHz as well as two edge-trigger chips with about 22 GHz of edge-trigger bandwidth. These components lend the scopes nicely to radar applications. There’s also a new 32-GHz sampling chip that requires no digital bandwidth interleaving or DSP boosting to reach the rated bandwidth. Both of those techniques introduce increased noise density, cause measurement inaccuracies, and result in nonlinear frequency response. In contrast, not only does this front end deliver superior pulse distortion control and significant margins in speed and fidelity, it also offers headroom for higher speeds in the future.
So what does all this mean in terms of measurement capability and accuracy? For one thing, with all of that true analog bandwidth, the 90000 X-Series scopes (Fig. 2) can make measurements that lesser instruments can miss, such as the fall time on a 13.5-ps edge. Moreover, the scopes’ low noise floor lends them greater measurement accuracy at equivalent bandwidths compared with competitive instruments. A lower noise floor allows for the capture of additional harmonic signal content.
Without a suitable probing system, it doesn’t matter what your scope’s bandwidth is. Agilent has rolled out the InfiniiMax III 30-GHz probing system for the 90000 X-Series scopes. The system is accompanied by a full suite of accessories that allow the probe to work in a number of different environments, including 2.92/3.5-mm pitches, solder-in scenarios, and browsing. For browsing, Agilent has built in a pitch-adjustment wheel on the browser tip as well as an LED “headlight.” Moreover, the InfiniiMax III probing system is upgradeable from 16 GHz up to 30 GHz, so it can support future expansion in your scope’s capabilities.
Calibration software performs a full ac calibration of the probing system. The scope pulses out a signal with a fast edge and automatically performs time-domain reflectometry on the entire probing system to the tip of the browser. The probe amplifiers carry their own individual S-parameter files preloaded on EEPROM, ensuring the greatest possible measurement accuracy.
To help designers get the most out of these scopes. Agilent offers a comprehensive lineup of application-specific measurement packages. Included is a broad range of jitter, triggering, analysis, and display tools, as well as pre-built compliance-testing software that was put together with the aid of Agilent engineers who serve on the standards committees in question. The packages support emerging high-speed serial-bus standards including the QuickPath interconnect, Fibre Channel, SAS 12G, and 10-Gbit/s Ethernet.
One example of an application-specific measurement software package is InfiniiSim for De-embedding, which combines measurements with transmission-line models to view simulated scope measurements at any location along a signal path. Additionally, equalization is becoming an integral part of high-speed serial technologies. The 90000 X-Series scopes support this with Agilent’s SDE software, which provides full DFE, FFE, and CTLE analysis. The software allows you to use your own tap values or let the instrument find the optimal tap values for a given signal.
Lastly, these scopes stand ready for emerging standards, proprietary standards, or whatever may come along in the future. Agilent’s User-Defined Application software provides a framework for the development of automated compliance testing on proprietary buses or on emerging standards that have yet to solidify.
Prices start at $131,000 for a two-channel, 16-GHz model and range up to $286,000 for the high-end version. Limited shipments begin in July.