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Rohde & Schwarz enters oscilloscope market with 1-2 GHz product

In a move that company executives say will fill out its range of instrument offerings, Rohde & Schwarz has introduced two series of oscilloscopes. The RTM and RTO ranges occupy what R&S calls the “performance” sector – 500 MHz to 4 GHz bandwidth – as opposed to the “basic” lower-bandwidth market, or the “high end” product area above 4 GHz. R&S already sells lower-cost instruments into the basic market under its Hameg brand, and hints that it may further expand into high-end oscilloscopes at some future date.

As with most digital oscilloscope product ranges, RTO and RTM-series units will both be available in 2- or 4-channel variants. R&S says it will differentiate its instruments from others in the market on a number of key points, for example, low noise floor, greatly-reduced measurement dead-time, fully-digital trigger scheme, and an innovative user interface. The company developed its own silicon-germanium front-end and analogue-digital converter (ADC) ICs to yield a noise floor sufficiently low to allow full input bandwidth at maximum input sensitivity of 1 mV/division, and a resolution ENOB (effective number of bits) of over 7. A single-core ADC (one per channel) avoids the jitter problems associated with interleaving multiple converters.

A s with other DSOs, the RTO series operate on a cycle of sampling and writing samples to memory, followed by processing and display of Rohde & Schwarz enters oscilloscope market with 1-2 GHz productwaveforms. At maximum sampling speed, some ’scopes may only spend 0.5% of their time capturing, so they are “blind” for the other 99.5%, R&S asserts. Following the RTO’s input stages, R&S engineers designed a 15 million-gate CMOS ASIC, in 90-nm technology, that implements 20 parallel processing paths to store captured data to memory, and to process the waveforms. This strategy increases the proportion of the measurement time in which the ’scope is capturing data 20-fold to 10%, increasing the statistical likelihood of capturing infrequent or randomly-occurring signals. All algorithms used by the parallel processing paths execute directly in hardware; the 250 mm² chip consumes around 60W. It also contains a custom memory-management unit that R&S designed to access standard DDR2, 800 MHz DRAM. Other functions in the ASIC include trigger processing, which operates on the captured and digitised signal waveforms, essentially eliminating trigger jitter. Once again, R&S hard-coded the algorithms to implement all familiar trigger options in silicon. At maximum sample rate – 10 Gsamples/sec, 1000 samples/waveform, 10% measurement cycle – the instrument will acquire and display 1million waveforms/sec (reduced if you add complex signal processing steps). “Many [‘scope data sheets] focus on their speed of writing data to memory,” says director of the oscilloscope division Josef Wolf, “but it takes forever to read it out.” Triggering options include the ability to carry out mask testing at full data- acquisition speed and, with a digital architecture, absence of any trigger re-arm interval.

You can control the RTO via front panel, mouse or its resistive touch-screen; you can also control it via a touch-screen interface from any monitor that emulates a USB mouse. While being Windows-based, the user interface is highly-customised. Single touches invoke measurement tools, set up waveforms, allocate them (via drag-and-drop) to separate or overlaid areas of the screen, collapse them down to active icons, and set up measurement parameters. Other features include a probe with a “microbutton” control right at the probe tip that you can assign a number of functions to; and a separate high- accuracy digital voltmeter measurement channel fed directly from the probe tip.

RTO oscilloscopes will cost from around €12,000, with 1 or 2 GHz bandwidth and 20 Msample/channel memory (extensible to 100 Msamples/channel). At €5000 upwards, the RTM series has a 500 MHz bandwidth, a smaller screen that does not have the touch-control facility of the RTO, and sampling rate of 5 Gsamples/sec maximum (2.5 Gs/samples/sec on two channels). With a conventional trigger architecture, the RTM series shares the low-noise input and full-speed/full-bandwidth at maximum-sensitivity capabilities of the RTO.

—by Graham Prophet

Rohde & Schwarz, www2.rohde-schwarz.com/en/products/test_and_measure