Oscilloscopes are the workhorse test instruments of any electronic design bench, and the MDO4000 lines of mixed-domain oscilloscopes (MDOs) from Tektronix have brought extended capabilities to these invaluable instruments by including spectrum analyzers. To make them even more accessible, the firm recently announced two low-cost additions to the MDO4000 product line: models MDO4014-3 and MDO4034-3, with analog bandwidths of 100 and 350 MHz, respectively. These versatile test tools each offer 4 analog channels, 16 digital channels, and one RF channel, with an RF range that can extend to 3 GHz.

Just what is a “mixed-domain oscilloscope?” In the case of the MDO4000 instruments (see figure), the term refers to the combination of a traditional oscilloscope and an RF spectrum analyzer. Each MDO4000 model can capture time-correlated analog, digital, and RF signals across its operating bandwidth, but also tracks how the spectrum changes over time by using the spectrum-analyzer functionality. These combination testers provide support for as much as 3 GHz capture bandwidth in a single acquisition—considerably wider than traditional RF spectrum analyzers. In addition to triggering on events with the oscilloscope, the MDO4000 instruments can also trigger on RF signals to help isolate an event of interest. These two new MDO4000 scope/analyzers start at about $12,200, providing somewhat less analog bandwidths than the higher-end model, but still with 3-dB bandwidths of 100 or 350 MHz that can be applied to many applications.

Both models MDO4014-3 and MDO4034-3 cover a spectrum analyzer (RF) range of 50 kHz to 3 GHz. The instruments differ by their analog bandwidths, as mentioned previously. Both integrate the functionality of an oscilloscope with that of a spectrum analyzer, logic analyzer, and protocol analyzer. They feature a maximum capture rate of 50,000 waveforms/s and provide more than 125 trigger combinations. The trigger acquisition system in these instruments is fully integrated with the RF, analog, and digital channels.

A single trigger event coordinates signal acquisition across all channels. A variety of time-domain triggers are provided, including edge, sequence, pulse width, timeout, runt, logic, setup/hold violation, video, and rise/fall time triggers. In addition, triggering can be performed on the power level of the RF input signal, such as when a transmitter turns on. With an optional module the RF input can also be used as trigger source for timeout, sequence, pulse width, runt, or logic triggering.

The screen can show both time- and frequency-domain information. When the RF channel and any analog or digital channels are active, the display is split into two views: The upper half shows a traditional oscilloscope screen with a time-domain display, while the lower half shows the frequency-domain view of a spectrum analyzer. The spectrum shown in the frequency-domain view is for the period of time—spectrum time—indicated in the time-domain view, showing how the RF spectrum changes over time.

The new instruments both include four Universal Serial Bus (USB) 2.0 ports, two on the front and two on the back, along with an RS-45 local-area-network connector. They show signal information on a 10.4-in. (264-mm) liquid-crystal TFT color display with resolution of 1024 x 768 pixels. The display scale can be set from 1 mV/div to 1 V/div. The instruments measure 17.3 x 9.0 x 5.8 in. (439 x 229 x 147 mm) and weigh 11 lbs (5 kg). They are equipped with low-capacitance, wide-bandwidth passive probes, and are available with optional serial-bus analysis capability for studying USB, MIL-STD-1553, RS-232, and other serial buses. In addition, the firm has announced the new model TRA-N-PRE preamplifier with bandwidth of 9 kHz to 6 GHz for improving the sensitivity of low-level measurements. It provides nominal gain of 12 dB and a 10-dB improvement in displayed average noise level (DANL).

Finally, the company has also introduced the SignalVu-PC vector signal analysis software for use with the oscilloscopes. The MDO4000 series instruments can save baseband In-phase (I) and quadrature (Q) data from complex modulated wireless signals into the .TIQ file format, ideal for import into SignalVu-PC running on a laptop or personal computer (PC) for analysis. For example, this allows EVM measurements on an OFDM IEEE 802.11g wireless local area network (WLAN) signal (Fig. 2: OFDM.png). The software can be used for settling time measurements, pulse measurements, and general modulation analysis, and can even show constellation diagrams.

Tektronix, Inc., 14150 SW Karl Braun Dr., P.O. Box 500, Beaverton, OR 97077; www.tek.com.