DIGITAL SIGNAL generation has truly become compact, thanks to the SMS-AWG Digital Waveform Generator from Spinnaker Microwave. The tiny source is a full-fledged arbitrary waveform generator (AWG) for intermediate-frequency (IF) signals. It is based on a high-speed digital-to-analog converter (DAC) that fits in a housing measuring just 4.0 x 4.5 x 0.75 in. with Micro-D 25/50-pin connector. Nevertheless, it can produce IF signals from DC to 1.1 GHz in the first Nyquist zone of DAC generation, and can reach 26 GHz with optional integrated frequency converters. The miniature source constructs analog waveforms from stored samples. These samples can define any waveform, from sine waves to serial digital pulses for applications ranging from commercial communications to military electronic-warfare (EW), RF simulation, and radar systems.

The DAC is controlled by a field-programmable gate array (FPGA) and fed by means of 32-Mb electronically erasable programmable read-only memory (EEPROM). This modular approach allows a user to predefine waveforms or load text-based files generated with programs such as LabVIEW from National Instruments or MATLAB from MathWorks.

The SMS-AWG Digital Waveform Generator (Fig. 1) can extend operation to 40 GHz with external frequency translators or to 26 GHz with an integrated converter (Fig. 2). The firm develops their own frequency synthesizers and upconverters/downconverters for use in receivers, transmitters, and test equipment. The AWG is based on a 14-b DAC that operates at sample rates to 2.5 GSamples/s. It can support modulation bandwidths as wide as 1 GHz in the standard AWG, and as wide as 2 GHz as an option. The frequency tuning speed, 100 ns or less, is ideal for both frequency-hopped communications and a variety of military intelligence and surveillance applications.

The SMS-AWG Digital Waveform Generator incorporates an internal low-noise 100-MHz DAC clock that can also be phase-locked to an external 10 or 100-MHz reference source. The AWG produces outputs to +10 dBm in the standard unit and to +20 dBm as an option, with output power maintained within 2 dB in both cases.

The source achieves impressive spectral purity, with harmonics of -50 dBc or less standard and -70 dBc or better as an option. The spurious content is dependent on the DAC modulation bandwidth. For full 1.1 GHz modulation, spurious is -55 dBc or less. For narrower modulation (e.g., 200 MHz), spurious is -70 dBc. Typical phase noise at 1.1 GHz is -120 dBc/Hz offset 1 kHz from the carrier, and -130 dBc/Hz offset 10 kHz from the carrier.

The SMS-AWG Digital Waveform Generator is programmable by means of low-voltage transistor-transistor logic (LVTTL) code. The optional frequency converter can be inserted into the unit's bottom deck for outputs to 26 GHz. The source runs on +5 VDC (and 1500 mA) and +15 VDC (and 150 mA). Other configurations are available.