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Anritsu's RF synthesizers span 'DC to daylight'

Posted: 31 Jan 2005 ?? ?Print Version ?Bookmark and Share

Keywords:anritsu? mg369xb? rf synthesizer? mg3691b? mg3692b?

Here's another example of a leading-edge RF product that's in lockstep with the wireless design revolution. Anritsu's high output-power menu-driven series MG369XB RF synthesizers are microprocessor-controlled signal generators touting very high resolution phase-locking.

They can generate both discrete CW (continuous wave), as well as broadband and narrowband step sweeps, and will do that across a frequency range of 2GHz to 65GHz, with phase offset adjustable in 0.1 steps.

What's more, a DDS (direct digital synthesizer) option will take one of these models down to just 0.1Hz (for CW and step sweep modes only; modulation and analog sweep aren't available at these low frequencies). The DDS imparts the family with the proverbial DC to light coverage, with frequency resolution to an amazing 0.01Hz (0.02Hz below 10MHz).

Modularity makes for cost-effectiveness
Six models are available, plus optional modules, which makes for cost-effectiveness. You can buy only what you need. The MG3691B covers 2GHz to 10GHz. An MG3692B increases coverage out to 20GHz, and a MG3693B brings you to 30GHz.

Similarly, a Model MG3694B extends coverage to 40GHz, and an MG3695B goes to 50GHz. Finally, the MG3696B spans 2GHz to 65GHz (it's operational to 67GHz).

Moving in the other direction, an optional down-converter can give you low phase-noise coverage from 10MHz to 2GHz. Phase noise is typically less than 130dBc/Hz (at 1GHz with 10kHz offset).

Actually, two options are available to extend the 2GHz low-end limit of MG3690B base models down to 10MHz. Option 4 uses a digital down-converter, with successive divide-by-2 circuitry. It offers the best phase-noise performance of the two choices, but trades off some analog performance below 500MHz.

In that range, analog sweep mode isn't available, and pulse modulation performance is typical. In addition, the frequency modulation and phase-modulation modulation index is scaled by the division ratio of each band of the digital down-converter. Option 5, however, maintains analog performance by using a heterodyne mixing down-conversion scheme.

Plentiful options
Kudos to Anritsu for offering these plentiful options, but there are more. You can opt for both mechanical and electronic step attenuators, special IF (intermediate frequency) inputs, an RF power monitor, and various pulse, AM, FM and phase modulation options, as well as a function generator, to name just a few. The IF-input option permits up-conversion of an externally IQ (in-phase and quadrature) modulated RF signal.

You also get flexible triggering choices, both internal and external. Sweep triggering is provided to do an analog frequency sweep, a step frequency sweep, a list frequency sweep and a CW power sweep. In Auto mode, triggers sweep automatically.

External triggers can sweep on low-to-high transitions of an external TTL signal. These TTL triggers can be applied at a rear-panel connector.

GPIB- compatible
Not mentioned in the company's press release is that although you can drive one of these MG3690B series synthesizers from its front panel, almost all functions are also remotely controllable using IEEE-488/GPIB (the General Purpose Interface Bus). Switching speed is typically just 5ms (for 1GHz steps), making these boxes suitable for fast-throughput RF test suites.

Whether you use GPIB or the front panel, the generator's output frequency can be swept digitally or using an analog ramp sweep, and a CW output can be phase offset or locked within an external PLL (phase locked loop). Amplitude, frequency, phase, and pulse modulation is also available, and the modulation can be applied from an external source or derived internally.

Under GPIB control or front panel control, up to four tables, with 2,000 non-sequential frequency/power sets, can be stored and then addressed as a phase-locked step sweep. One table of 2,000 points is stored in non-volatile memory, with the others stored in volatile memory.

Of course, you can select a manual sweep mode, too. It supports stepped, phase-locked adjustment of frequency between sweep limits, and the number of steps or step size is selectable.

Also, under GPIB control, more than 3,000 non-sequential frequency sets and power sets can be stored and addressed as a phase-locked step sweep. This data is also stored in volatile memory.

Software control
Software is also available that lets you apply various user-defined modulation types, some simultaneously. The software also permits down-loading user-defined modulation waveforms.

Finally, Anritsu makes provision for operating two instruments in a master-slave configuration. Beyond that, you can also readily hitch a MG3690B to Anritsu's Model 56100A scalar network analyzer. In that capacity, the synthesizer serves as the stable and settable signal source for the network analyzer.

Likewise, you can also connect a MG3690B to Anritsu's Model 360B VNA (vector network analyzer). The MG3690B then works as a signal source for the analyzer operating in a tracking receiver mode.

To its credit, Anritsu supports the MG3690B's ready use with popular instruments from other vendors, too. For example, if it has pulse modulation installed, you can let it serve as the RF source for a Gigatronics Model 8003 scalar network analyzer. Similarly, if your MG3690B has the pulse option installed, you can rapidly connect it to a Hewlett-Packard Model 8757D or Model 8757E scalar network analyzer.

- Alex Mendelsohn

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