Oscilloscopes Bring More Signals than Ever into View

Oscilloscopes Bring More Signals than Ever into View

When four channels aren’t enough, these real-time oscilloscopes capture as many as eight analog and 64 digital signals with up to 2-GHz bandwidth and sampling rates to 6.25 Gsamples/s.

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An oscilloscope may be the closest thing to a “universal” test instrument for most engineers. One is usually found on every testbench and design station, for checking both high-frequency analog and high-speed digital designs. But with electronic designs growing denser and more complex, traditional two- or four-channel oscilloscopes lack the firepower needed to test multiple-channel circuits and systems.

Fortunately, the designers at Tektronix have spent time looking and listening to what modern mixed-signal engineers need in terms of oscilloscope capability. The end result is an instrument family for today and tomorrow: the 5 Series mixed-signal oscilloscope (MSO) family, with as many as eight simultaneous measurement channels. Of course, having all of hose channels without top-level performance would be meaningless, and the 5 Series MSO instruments deliver with bandwidths as wide as 2 GHz, 12-b vertical resolution, and real-time sampling rates to 6.25 Gsamples/s.

The 5 Series MSO oscilloscopes are the culmination of some serious industrial as well as electronic design efforts. They are attention-grabbing and game-changing in both appearance and performance. In terms of appearance, perhaps the most noticeable features are the eight input ports and the large display screen. The eight input ports provide plenty of measurement flexibility—they can each be used for any variety of signals, including analog, digital, and power signals. The large screen is in strong contrast to a typical oscilloscope, where a screen might be about one-half of the front face, while all of the controls fill the rest of the instrument’s front face.

1. The 5 Series MSO oscilloscopes offer sampling rates to 6.25 Gsamples/s and bandwidths to 2 GHz with as much as 12-b vertical resolution (and 16-b vertical resolution with a high-definition function).

Look and Feel

The 5 Series MSO oscilloscopes show results on a large, 15.6-in. capacitive touchscreen with 1920- × 1080-pixel resolution (Fig. 1). It dominates the front face area of the instrument (about 85% of the total area), part of the clever industrial design of the oscilloscopes in which the majority of the control surface is on the touchscreen. The scopes incorporate an advanced graphical user interface (GUI); operators access controls by touching objects on the display screen rather than navigating through multiple layers of menus to try to find a desired control function. A user can reach control functions by touching icons on the screen or by connecting a computer mouse to click on the same icons.

For simplicity, a streamlined control panel, found to the right of the screen, contains the most essential controls, including trigger, vertical and horizontal scale and position, run/stop, and cursor functions. Also, the front panel includes LED rings that highlight selected waveforms and trigger sources for easy identification.

2. The intelligent industrial design of the 5 Series MSO oscilloscopes makes for easy transportability.

While the 5 Series MSO oscilloscopes are not meant to be portable, they are transportable (Fig. 2), designed with a slim (less than 8 in. deep) profile and constructed with a solid housing and strong metal carrying handle. In addition, they have fixed front feet and adjustable rear feet to set viewing angles to a personal preference. With the growing trend of working at home, these scopes can readily become part of that equation.

To achieve the compact design while, at the same time, achieving the equivalent of about a half-dozen different test functions, a new application-specific integrated circuit (ASIC) was developed as part of the multiple-year program to design and develop the oscilloscopes (Fig. 3). The ASIC combines an analog-to-digital converter (ADC), demultiplexer, trigger, and digital-acquisition components within a single IC. In addition, a new low-noise amplifier (LNA) helps improve the capture of extremely low-level signals.

3. A custom ASIC was developed with many of the front-end mixed-signal circuit functions, including a 12-b ADC.

The ADC provides as much as 12-b resolution for detailed waveform information. The vertical resolution is actually 8 b at 6.25 Gsamples/s and 12 b at 3.125 Gsamples/s. In addition, the 5 Series MSOs offer a high-resolution mode, in which 16-b vertical resolution is possible. This is achieved by using a digital-signal-processing (DSP) filter with finite-impulse-response (FIR) function at each sampling rate to limit bandwidth and noise and improve resolution.

Appearance is just part of the appeal of these oscilloscopes, which provide enough performance for most applications: their real-time sampling rate of 6.25 Gsamples/s can reach as high as 500 Gsamples/s through interpolation. They can capture more than 500,000 waveforms/s, and store data by means of standard record length of 62.5 Mpoints, and 125-Mpoints record length as an option. For truly critical timing measurements, the time base system can lock to a high-stability, external 10-MHz reference clock oscillator.

The 5 Series scopes come in three basic models—the MSO54, MSO56, and MSO58—with four, six, and eight channels, respectively (Fig. 4). Once the number of channels is selected, the choice of bandwidth is among 350 MHz, 500 MHz, 1 GHz, and 2 GHz. A choice of bandwidth need not be permanent, since the bandwidth can be upgraded to as much as 1 GHz in the field; upgrades to 2 GHz must be performed at a Tektronix service center.

4. The 5 Series MSO oscilloscopes are available as three models with four, six, or eight channels, and with different bandwidths.

Probing the Difference

Unlike conventional oscilloscopes with fixed input connectors that essentially determine the functionality for each input port, the 5 Series MSOs employ innovative FlexChannel technology on their input ports. These are basically flexible interfaces that allow an operator to choose a desired input channel configuration, using each input port as one analog channel or eight digital channels. Therefore, an eight-channel oscilloscope can handle as many as eight analog channels and as many as 64 digital channels. The channels can be configured for any mixture of analog and digital signals to support probing of the most complex mixed-signal circuit architectures.

The FlexChannel inputs on the oscilloscopes work with the firm’s TekVPI probe interface to enable connections to both analog and digital probes. All FlexChannel ports accept all TekVPI analog probes. When a TLP058 logic probe is connected, however, its single TekVPI connector is terminated in eight digital logic probe points. These eight logic channels run at the same maximum sampling rate (6.25 Gsamples/s) and bandwidth as the single analog channels. And there are no performance compromises for the additional signal channels, simplifying comparisons between different types of signals.

The TekVPI probes have status indicators and controls as well as a probe menu button on the comp box. Pushing the button activates a probe menu on the oscilloscope screen, with all relevant settings and controls for the probe. The TekVPI interface enables direct attachment of current probes without requiring a separate power supply.

5. The IsoVu technology uses optical communications and power-over-fiber to provide high-voltage isolation for the test probes.

TekVPI probes can be controlled remotely through a USB or LAN connection to a PC for ATE applications. The 5 Series MSOs provide as much as 80 W power to the front-panel connectors, enough to power all connected probes without need for an additional probe power supply.

The TekVPI interfaces on these oscilloscopes are fortified by the company’s IsoVu technology, which uses optical communications and power-over-fiber to achieve complete galvanic isolation for the test probes. This high-isolation technology (Fig. 5) helps resolve high-bandwidth differential signals in the presence of large common-mode voltages. For example, for bandwidths to 1 GHz, the probe and oscilloscope combination delivers 120-dB common-mode rejection at 100 MHz and 80-dB common-mode rejection at full 1-GHz bandwidth. The differential dynamic range is greater than 1000 V, with a 60-kV common-mode voltage range.

The 5 Series scopes include a complete set of triggering functions, such as runt, logic, pulse width, window, timeout, rise/fall time, setup-and-hold violation, serial packet, parallel data, and sequence triggers. They feature trigger and decode functions for most common serial standards, such as I2C, USB, CAN, and Ethernet interfaces. Digital phosphor technology reveals the most minute glitches and transient events. In addition, various optional software packages are available to assist with such tasks as jitter analysis (Fig. 6).

6. The low-noise front end, digital phosphor technology, and large touchscreen display speed the search for transient events and performing common measurement functions such as jitter testing.

The oscilloscopes provide Wave Inspector controls to scan quickly through a record in search of user-defined events. These controls allow an operator to perform searches based on different waveform characteristics, such as edge, pulse width, timeout, runt, window, logic, setup and hold, rise/fall time, and parallel/serial bus packet content.

The Extra Measurement Mile

If the oscilloscope measurement power wasn’t enough, the 5 Series MSOs are either equipped with or available with optional additional measurement functions. For example, a built-in four-digit digital voltmeter (DVM) and trigger frequency counter are activated upon product registration. A 50-MHz function generator and an arbitrary function generator are available as options, providing low-frequency waveforms or noise for testing. The scopes are compatible with the company’s ArbExpress PC-based software for quick creation of complex waveforms.

The MSOs also come with an optional solid-state drive (SSD) with 480-GB memory space for data storage and optional Windows 10 operating system (OS) from Microsoft Corp. Each oscilloscope can operate as a dedicated oscilloscope or in a Windows configuration simply by adding the SSD for Windows-based use; the instrument will boot up from the SSD and run on Windows. Once the drive is removed, the instrument will use its internal configuration. The 5 Series MSO oscilloscopes run an i5 dual-core microprocessor from Intel Corp. running at 2.7 GHz, aided by 16 GB of DDR3 DRAM and more than 80 GB of internal storage memory.

Each 5 Series MSO with 350- or 500-MHz bandwidth is shipped with one TPP0500B probe per channel. It has a 500-MHz bandwidth and low capacitive loading of 12.7 pF. Higher-frequency oscilloscopes are shipped with one TPP1000 probe per channel, which has a 1-GHz bandwidth and capacitive loading of 3.9 pF. Also included are a 20-pin DisplayPort connector, 29-pin DVI-D connector, and a DB-15 VGA connector to show the oscilloscope display on an external monitor. They also provide two USB 2.0 ports and one USB 3.0 port for external computer, printer, and other device connections. P&A: starting at $12,600.

Tektronix Inc., P. O. Box 500, 14150 SW Karl Braun Dr., Beaverton, OR 97077; (800) 833-9200, www.tek.com.

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