Contactless probes expand possibilities for logic analysis - Embedded.com

Contactless probes expand possibilities for logic analysis

Contactless probes expand possibilities for logic analysis

Tektronix is using silicon germanium in six logic analyser modules and has developed a revolutionary probing system to provide simultaneous analog and digital measurements.

When troubleshooting and debugging a digital system, one of the first and most challenging tasks for an engineer is obtaining a clear signal to analyse. Until now, design engineers using a logic analyser were typically forced to install permanent connectors on their circuit boards in order to probe the system. Also, to access both the analogue and digital characteristics of each signal, an increasing need as designs become faster and more complex, multiple connectors and probes were required.

Tektronix' connectorless probing system — a feature of six additional TLA7Axx logic analyser modules that provide 8GHz timing acquisition rate — aims to provide a solution more advanced than any other probing technology on the market. The probing system saves costs by eliminating the need for connectors, and enables engineers to access the signal directly. At 0.7pF, the connectorless probing system provides a reduced total capacitance, thereby increasing the quality of its signals. And says the company, for the first time ever, users can obtain analog and digital measurements (both timing and state) through a single probe.

The TLA7Axx modules improve the debug and verification of digital systems. It provides 8GHz (125ps) timing simultaneous with state acquisitions from 120MHz up to 800MHz clock rate and up to 1.25Gbit/s data rate. The TLA7Axx also features up to 2GHz deep timing and is available in 34, 68, 102 and 136 channel configurations. 680 channels on a single time base is achieved using merged modules.

The acquisition memory of the new modules, with up to 256 million samples, is deep enough to capture long time spans, even at high clock rates. This feature, plus the system's ability to support 34, 68, 102, 136 channel configurations and up to 680 channels on a single timebase using up to five merged modules at full performance, is in keeping with the advancing complexity and pin counts of today's processors and chipsets.

Using the TLA7Axx modules' 2GHz analog multiplexer, users can route the analog signal of any four logic analyzer channels to an oscilloscope. The signal is delivered to an external oscilloscope such as the TDS6604 (or other Tektronix TDS oscilloscopes or TLA oscilloscope modules) and is displayed time correlated on the logic analyzer's screen with the logic analyzer's digital timing waveforms, state tables and embedded software traces. This integrated configuration presents real-time, correlated digital and analog traces on the same display, making it easy to spot the analog causes of digital signal integrity problems.

The P6860 high-density probe for single-ended signals and the P6880 high-density probe for differential signals eliminate multiple connections to the system under test, saving setup time and sparing users the difficult chore of connecting separate logic analyser and oscilloscope probes to the same test point. A third new probe, the P6810, is a general-purpose probe for both single-ended and differential signals and is compatible with conventional connectors.

The P6860/80 logic analyzer probes connect directly to a PCB land pattern on the target board. It is a probing solution with only 0.7pf of capacitance and provides singled-ended and differential measurements with no channel count tradeoffs. Logic analyzer users have a substantial investment in hardware, software, training, and fixturing for their tools.

With a free software update the new TLA7Axx modules are fully compatible with TLA700 series mainframes with Microsoft Windows 2000 Professional. Existing TLA600 and TLA700 setups are compatible with the new TLA7Axx modules. A trade-in credit is available for older TLA700 Series mainframes, and the system architecture allows customers to configure their logic analyzer for current needs and upgrade later.

Adapters match the new modules to legacy development boards and processor support packages. These adapters mate the P6860/80 connector-less probes to existing Mictor connectors on development boards and processor support adapters.

The TLA700 series is a configurable, modular logic analyser family that provides improved performance in sample rate, channel count, timing resolution, record length, and microprocessor support. The series includes mainframes, digital acquisition modules, pattern generator modules and integrated digital storage oscilloscope (DSO) modules.

Meeting these challenges requires some preparation in advance. Most importantly, it is necessary to design in test points for the instrumentation. Usually this involves installing a Mictor connector for the logic analyzer and dedicated pads for oscilloscope probing. But now the paired logic analyzer/oscilloscope toolset carries the integrated instruments' capabilities all the way to the test point.

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