Company
2020-11-27

RFHIC’s 6kW, Gallium-Nitride (GaN) Solid State Microwave Generators (SSMG) for Next Generation Industrial, Scientific, and Medical Applications

RFHIC’s 6kW, solid-state microwave generator provides enhanced performance for various 2.4-2.5 GHz industrial, scientific, and medical (ISM) applications. The 6kW, gallium-nitride (GaN) solid-state microwave generator is designed as a one to one replacement of bulky and unreliable tube-based power systems (magnetrons, klystrons, etc.) for various applications such as:

RFHIC’s compact and lightweight RIU256K0-40TG (6kW, GaN solid-state microwave generator) generator operates from 2.4 to 2.5 GHz, combining four 1.6 kW gallium-nitride (GaN) power amplifiers  (PAs) into a remote, solid-state head. The complete microwave generator system comes with a power supply unit, solid-state power amplifier (SSPA) head, cable assembly, and waveguide converter. (see Figure 1).

 

The solid-state power amplifier (SSPA) supports both CW and pulse operation and can be customized to end-user application requirements. With an adjustable power range from five to 100 percent of rated output, the RIU256K0-40TG (6kW, GaN solid-state microwave generator) maintains high system efficiency at both low and high power (see Figure 2).

 

rfhic 6kw SSPA System Efficiency

RFHIC’s 6kW, GaN Solid State Microwave Generator (SSMG) Efficiency Chart

Each of the four gallium-nitride (GaN) power amplifiers (PAs) in the generator uses RFHIC’s high-performance gallium-nitride (GaN) on silicon-carbide (SiC) transistor technology, which provides wide bandwidth, high efficiency, high breakdown voltage, and reduces the overall size of the system. The RIU256K0-40TG (6kW, GaN solid-state microwave generator) uses 200 W transistors (IE24200P), which have a saturated output power of 230 W and 74 percent drain efficiency at 50 V bias. The fully matched transistors are integrated with DC blocking capacitors on both RF ports to simplify system integration.

GaN Solid-State Power Amplifier (SSPA) VS. TUBE

Many historic RF energy applications use vacuum tubes or magnetrons as the core power source. Such systems have significant disadvantages controlling the frequency, power, and phase. The RIU256K0-40TG (6kW, GaN solid-state microwave generator) includes RFHIC’s drive and control module to precisely set the output frequency and power, and the generator delivers a clean signal with low noise and spurious compared to a magnetron (see Figure 3).

 

rfhic 6kW signal purity

1kW, 3kW, 6kW Magnetron vs. GaN Solid-State Signal Comparison Graph

 

Another advantage is the capability to generate full power without any warm-up time. Tubes have short lifetimes of-ten less than 6,000 hours causing downtime and increasing operating costs. The RIU256K0-40TG’s (6kW, GaN solid-state microwave generator) lifetime is between 50,000 and 100,000 hours, depending on the operating conditions, which yields significant cost savings. Unlike magnetrons and other tube-based systems with a single power source, the RIU256K0-40TG (6kW, GaN solid-state microwave generator) combines four rugged GaN solid-state power amplifiers (SSPAs), enabling the system to degrade gracefully if one of the PAs fails. Tube-based systems require high voltage power supplies inside the generator, which are susceptible to arcing. The GaN solid-state power amplifier (SSPA) operates at a safer voltage of 50 V. The RIU256K0-40TG uses water cooling to eliminate large metal heat sinks and reduce generator size. With water cooling, the SSPA can be compatible with the existing cooling infrastructure for a tube-based system, which reduces installation and operating costs for the customer. The system has multiple sensors to detect water flow rate, SSPA temperature, and VSWR. In case of abnormal operation, the system will automatically shut down and alert the user, ensuring the generator is not damaged. The RIU256K0-40TG has an LCD touch-screen and jog wheel, providing full access to the system controls, sensors, and alarms; full monitoring and management are also accessible using a laptop or remote PC. Controlling the system remotely via PLC, CAN or Bluetooth is available as an option.

 

MODULAR DESIGN

The RIU256K0-40TG (6kW, GaN solid-state microwave generator)  is a stand-alone, rack-mounted system with two parts:

  • GaN solid-state power amplifier (SSPA) head with an isolator: 42.4 cm wide, and 74.7 cm long, 25.6 cm high, and weighs 41 kg.
  • The power supply is 48.3 cm wide, 43.2 cm long, 17.7 cm high, and 29 kg.

The power supply uses three-phase, 380 V AC and generates the 50 V bias for the gallium-nitride (GaN) on silicon-carbide (SiC) transistors. The power supply contains three rectifier modules designed to load share, be hot-swappable, and n+1 redundant, meaning the SSPA will continue to operate if one of the power modules fails. The failed module can be replaced without replacing the entire generator. Four 1.6 kW SSPAs are combined to produce the 6 kW CW output, using RFHIC’s four-way waveguide combiner. From 2.4 to 2.5 GHz, the WR340 combiner has a maximum insertion loss of 0.1 dB with 1.1:1 VSWR and less than 3 degrees imbalance among the ports. The generator is scalable, meaning users can add RFHIC’s commercial off-the-shelf PAs without manual phase synchronization. This flexibility maximizes amplifier utilization, reduces capital expense, and shortens development time.

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