AR’s 6 – 18 GHz Solid State Amplifiers Provide High Gain,
Low Noise, Good Linearity, and Excellent Mismatch
Capability for EMC and Non-EMC Testing
By AR

If you’re conducting EMC or non-EMC testing in the 6 – 18 GHz frequency range, there are now excellent alternatives to both Traveling Wave Tube Amplifiers (TWTAs) and to solid state GaAs MMIC technology amplifiers.

With its first solid state amplifiers that reach 18 GHz, AR RF/Microwave Instrumentation now offers two solid state microwave amplifiers that cover the 6 – 18 GHz frequency range. Model 5S6G18 (5 Watts) and model 20S6G18 (20 Watts) provide high gain, low noise, good linearity, and excellent mismatch capability. These units also deliver superior EVM (Error Vector Magnitude) performance. Both units operate from AC and provide instant power with no warm-up time needed.

Product Design
The 5S6G18 and 20S6G18 solid state amplifiers’ block diagrams are shown in Figures 1 and 2 respectively. Both designs utilize numerous GaAs FETs and MMICs in a balanced configuration. All devices are biased Class A using an active bias circuit. The output stages are combined using AR proprietary technology.

Model 5S6G18 features a minimum of 5 Watts output power, a minimum 37dB of gain and typical noise figure of 6dB (a significant improvement over TWTAs). Gain flatness is within +/- 2.0dB across the band. All 2nd harmonics are better than -20dBc and third-order intercept is typically +46dBm. The broadband amplifier is protected with an overdrive circuit at the input.

Model 20S6G18 features a minimum of 20 Watts output power, a minimum 43dB of gain and typical noise figure of 6dB (a significant improvement over TWTAs). Gain flatness is within +/- 2.0dB across the band. All 2nd harmonics are better than -20dBc and third-order intercept is typically +48dBm. The broadband amplifier is protected with an overdrive circuit at the input.

Advantages Over Solid State Amplifiers Using GaAs MMICs Technology
The 5S6G18 and 20S6G18 solid state amplifiers from AR are based on a hybrid thin film and GaAs chip technology that represents a significant improvement over solid state amplifiers that use GaAs MMIC technology. The AR amplifiers deliver superior performance for power output, IP3, harmonics and gain flatness, and mismatch capabilities.

Figure 5 shows shows the superior intermodulation performance of AR’s FET Chip technology as compared to MMIC technology.

Another advantage over MMIC technology is that AR’s FET Chip technology enables the amplifier to be built to specific needs, whereas MMIC technology results in a more uniform, “cookie-cutter” amplifier.

Compared to TWTAs
These solid state amplifiers also offer significant advantages over TWTAs in similar applications. For example, as the tube of a traveling wave tube amplifier ages, the output power decreases and readjustment is required. Eventually the tube will need to be replaced. But solid state microwave amplifiers do not require adjustment; and they outlast TWTAs. The average mean time between failures for a solid state microwave amplifier is greater than 20 years. For a TWT, it’s an average of 8 years. In addition, the solid state microwave amplifiers provide a much cleaner, more stable and better intermodulation performance. Our solid state units are 100% load tolerant without power foldback and the TWT must be protected from mismatches when greater than 2:1 VSWR is present.

Additional Features
Model 5S6G18 and 20S6G18 are protected from RF overdrive by an RF input leveling circuit that controls the input level applied to the first stage of amplification when the RF input is increased above 0 dBm. The individual RF amplifier stages are protected from over temperature by removing the DC voltage applied to them if an over temperature condition occurs due to a cooling blockage or fan failure. There is a digital display on the front panel to indicate the operational status and fault conditions when an over-temperature or power supply fault has occurred. The unit can be returned to normal operation when the condition has been cleared.
Both units feature a digital control for both local and remote control of the amplifier. This eight-bit RISC microprocessor-controlled board provides both IEEE-488 (GPIB) and asynchronous full duplex RS-232 control of all functions. Also included are USB 2.0 and Ethernet interfaces.

Expandable Power
In keeping with AR’s commitment to providing equipment that can grow along with the user’s needs, the 5S6G18 (5 Watts) can be expanded to 10, 20 or even 40 watts. In fact, AR makes the only 40-Watt amplifier in this frequency range.

According to Donald “Shep” Shepherd, AR chairman, “The 6 – 18 GHz solid state amplifiers are innovations that reflect AR’s leadership in the industry and its ability to combine the resources of all AR companies to continually introduce breakthrough solutions.”

AR
www.ar-worldwide.com
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