RFHIC’s 6kW, 2.45GHz GaN Solid State Microwave Generator

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:

• Chemical vapor deposition (CVD) reactors used for artificial gemstone growth
• Plasma Vapor Deposition (PVD) Thin Film reactors are used to manufacture thin films for semiconductor applications
• Microwave heating and drying for industrial food processing applications

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).

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

Historically, numerous RF energy applications relied on vacuum tubes or magnetrons as their primary power source. However, these systems came with notable drawbacks in terms of frequency, power, and phase control. In contrast, the RIU256K0-40TG (6kW, GaN solid-state microwave generator)incorporates RFHIC's advanced drive and control module, enabling precise adjustment of both output frequency and power. As a result, this generator produces an exceptionally clean signal with minimal noise and spurious interference, far surpassing the performance of traditional magnetrons (refer to Figure 3).

Another significant advantage lies in the ability to instantly generate full power without any warm-up time. In contrast, tubes often have short lifespans, frequently less than 6,000 hours. This not only leads to downtime but also escalates operating costs. The RIU256K0-40TG (6kW, GaN solid-state microwave generator) boasts an impressive lifespan ranging from 50,000 to 100,000 hours, depending on operating conditions. This extended longevity translates to substantial cost savings.

Unlike magnetrons and other tube-based systems reliant on a single power source, the RIU256K0-40TG (6kW, GaN solid-state microwave generator) features a configuration with four robust GaN solid-state power amplifiers (SSPAs). This design ensures graceful degradation in case one of the PAs encounters an issue. In contrast, tube-based systems necessitate high-voltage power supplies within the generator, which are prone to arcing. The GaN solid-state power amplifier (SSPA) operates at a safer voltage of 50 V.

Furthermore, the RIU256K0-40TG implements efficient water cooling to eliminate the need for large metal heat sinks, thus reducing the overall size of the generator. This innovative approach allows the SSPA to seamlessly integrate with existing cooling infrastructure in tube-based systems, resulting in cost savings during installation and operation. The system incorporates multiple sensors to monitor water flow rate, SSPA temperature, and VSWR. In the event of abnormal operation, the system automatically initiates a shutdown and alerts the user, safeguarding the generator from damage.

The RIU256K0-40TG also offers user-friendly controls with an LCD touch-screen and jog wheel, granting complete access to system controls, sensors, and alarms. Additionally, comprehensive monitoring and management are accessible through a laptop or remote PC. For added convenience, the system can be controlled remotely via PLC, CAN, or Bluetooth, providing users with versatile options for system management.

MODULAR DESIGN

The RIU256K0-40TG (6kW, GaN solid-state microwave generator) is a self-contained, rack-mounted system comprising two main components:

GaN Solid-State Power Amplifier (SSPA) Head with Isolator: This unit measures 43.2 cm in width, 90.2 cm in length, 23.8 cm in height, and weighs 54.2 kg.Power Supply: The power supply unit has dimensions of 48.3 cm in width, 43.2 cm in length, and 17.7 cm in height, with a weight of 29 kg.The power supply operates on a three-phase, 380~480 VAC and generates the required 50 V bias for the gallium-nitride (GaN) on silicon-carbide (SiC) transistors. Notably, the power supply incorporates three rectifier modules designed for load sharing, hot-swappability, and n+1 redundancy. This means that if one of the power modules fails, the SSPA can continue to operate without the need to replace the entire generator.

To achieve a 6 kW continuous wave (CW) output, four 1.6 kW SSPAs are combined using RFHIC's four-way waveguide combiner. Operating within the 2.4 to 2.5 GHz frequency range, the WR340 combiner offers exceptional performance, with a maximum insertion loss of 0.1 dB, a 1.1:1 voltage standing wave ratio (VSWR), and an imbalance of less than 3 degrees among its ports.

Additionally, the generator is designed with scalability in mind. Users have the flexibility to integrate RFHIC's commercial off-the-shelf power amplifiers (PAs) without the need for manual phase synchronization. This adaptability maximizes amplifier utilization, reduces capital expenses, and shortens development timelines.

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