Analogue RF & microwave signal generator offers lowest phase noise
Rohde & Schwarz aims the SMA100B at the RF semiconductor, wireless communications and aerospace and defence industries. An example specification point for phase noise is –152 dBc/Hz at 20 kHz offset from 1 GHz. The 6 GHz version of the instrument generates up to 38 dBm RF output power, and the 20 GHz instrument generates up to 32 dBm in the microwave frequency range. Harmonics are extremely low across the entire frequency range; above 6 GHz they are significantly lower than 70 dBc at 18 dBm output power. Nonharmonics are below 110 dBc at an output signal of 1 GHz. The instrument comes with a range of options, for example low noise and ultra low noise; high output power and ultrahigh power; and a second, reference signal output option. It comes in a 3U high format for bench use with a 7-in. touchscreen : or a 2U high version with 5-in. screen for incorporation into ATE racks.
“The R&S SMA100B enables our customers to verify the true performance of their DUTs without the signal source affecting the results,” says Andreas Pauly, Vice President Signal Generators, Audio Analyzers and Power Meters at Rohde & Schwarz.
An example quoted is test of state-of-the-art ADCs and DACs, that require absolutely pure signals with the lowest phase and wideband noise possible. In addition to delivering extremely pure analogue RF signals, the SMA100B is the only analogue signal generator available (R&S says) that can simultaneously provide a second, independently configurable, extremely pure and synchronized clock signal up to a frequency of 6 GHz. As a result, engineers can characterize ADCs with a single analogue signal generator. The extremely low wideband phase noise of the clock synthesizer output signal (100 MHz, –175 dBc/Hz, 30 MHz offset) makes it possible to measure the true signal-to-noise ratio of modern ADCs. The ‘clock’ output has similar phase noise characteristics to the RF output, and its wideband noise is “even better”.
Commenting from Analog Devices, Ron Goga, Test Director of High Speed A/D Converters, says, “The close cooperation between our two companies and the timely release of the R&S SMA100B with extremely pure analogue RF signals up to 20 GHz coincides with the release of Analog Devices’ new RF series of converters, which includes the AD9208 dual 3 Gsample/sec 14-bit A/D converter and AD9172 dual 12 Gsample/sec 16-bit D/A converter. The state-of-the-art performance of the R&SSMA100B allows us to continue to showcase our RF data converters in the best possible light.” When characterizing DACs, the generatorʹs extremely low phase noise produces minimal signal jitter that does not influence the measurement results.
For working with radar signals, and with signal generation functions such as a radar local oscillator, the SMA100B has a powerful pulse modulator and generates pulses with extremely short rise and fall times and an on/off ratio below 90 dB. Digital, high-precision automatic level control (ALC) ensures that the absolute top power levels of narrow pulses are output in a highly accurate, reproducible manner. Closed loop level control is available for pulse widths starting at 100 nsec. These characteristics make it possible to test advanced radar receivers with unmatched accuracy under demanding pulse scenario conditions.
Extremely pure local oscillator signals are often required to verify system performance before the overall integration of a radar system can take place. The SMA100B can provide high-level signals with extremely low, close-in phase noise, for example, –83 dBc/Hz at 10 Hz away from 10 GHz. In base station design, and when simulating in-band or out-of-band interferers, the instrument’s ultra low phase noise option ensures that phase noise and wideband noise from the simulated interferer have a minimal impact on the wanted signal. A base station’s true interference suppression performance can be demonstrated; for example, wideband noise at 10 GHz is below –160 dBc/Hz at 30 MHz offset.
The ultra high output power option enables the SMA100B to provide up to 38 dBm of output power, eliminating the need for external amplifiers in automated test environments. R&S notes that this is enough power to easily damage sensitive circuitry: therefore, the instrument has the facility to set a maximum-output “over-ride” level. With its integrated, wear-free electronic step attenuators now standard also in the 20 GHz instruments, operational life of test systems is extended, with zero wear on the instrument. This solution also offers extremely fast level setting times for the first time ever in a microwave signal generator.
As well as consolidating R&S’ range by superseding two previous instruments, the unit has menu options to emulate a number of older signal sources, so that it can be drop-in replacement in running test systems.
Rohde & Schwarz; www.rohde-schwarz.com/ad/press/purest-signal
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