6–18 GHz 50 W Broadband GaN SSPA for Radar and EW Applications

The MCW6018M47A is a broadband solid-state power amplifier (SSPA) covering the 6–18 GHz frequency range for radar, EW, and RF test applications. Achieving flat gain response across a multi-octave bandwidth while maintaining a compact footprint remains a key challenge in broadband RF amplifier design. Flat gain is critical because it minimizes amplitude calibration errors across broadband system sweeps, preventing power drop-outs during critical frequency hops. Legacy traveling-wave tubes (TWTs) and GaAs architectures require high operating voltages or bulky multi-stage combining topologies. Transitioning to this 6–18 GHz GaN power amplifier enables SWaP optimization while maintaining flat broadband RF performance across multi-octave bands.

By integrating bare GaN die using chip-and-wire assembly, this broadband solid-state power amplifier bypasses the physical limits of standard packaging to achieve high power density. The resulting module delivers a typical saturated output power of 50 W across the complete 6000 MHz to 18000 MHz operating band.

SWaP Advantages and Assembly Architecture

The microelectronic architecture of the MCW6018M47A provides several packaging and assembly advantages over standard packaged layouts:

• Chip-and-Wire Interconnects: This assembly technology reduces the parasitic capacitance and inductance introduced by standard plastic packaging. Eliminating these parasitics ensures smooth, predictable gain transitions up to 18 GHz.
• Compact Mechanical Form Factor: The module measures 190 × 90 × 25 mm with a maximum weight of 2 kg. This compact footprint reduces mechanical loading on the mounting chassis and heatsink, allowing deployment in dense airborne payloads.
• Solid-State Reliability: The semiconductor structure yields extended operating lifetimes compared to legacy vacuum-tube devices, lowering overall system maintenance intervals.

1. Electrical Performance and RF Efficiency Benchmarks

Operating from a nominal 28 VDC supply, the amplifier draws a typical 7 A at 50 W saturated output.

Key RF metrics across the operating band include:

• Power Gain: Achieves a typical power gain of 47 dB. High gain eliminates the need for multi-stage driver chains, allowing low-power synthesizers to drive the SSPA directly to full saturation.
• Impedance Matching and Return Loss: Input return loss is better than 10 dB into a standard 50 Ω RF network. This reduces reflection mismatches at the input interface, stabilizing the preceding driver stage.
• Spectral Purity: Spurious signal outputs are suppressed to -60 dBc typical. This deep suppression minimizes unwanted spectral emissions, preventing out-of-band interference in dense signal environments.

2. Interface Pinout and Real-Time Telemetry

A hybrid 7-pin D-Sub connector provides a standardized interface for power supply inputs and analog monitoring. The pin mapping allows direct analog telemetry to simplify predictive maintenance and system diagnostics:

• Pins A1 / A2 (VDD / GND): Dedicated high-current pins supporting operating voltages from 26 V to 32 V (28 VDC nominal).
• Pin 1 (ENABLE): Employs TTL logic high (3.3 V) to enable the amplifier, featuring an internal pull-low circuit to prevent accidental transmission if control logic floats.
• Pin 2 (CURRENT MONITOR): Provides real-time analog current telemetry scaled at 100 mV/A to track overall power consumption changes.
• Pin 3 (TEMP MONITOR): Provides baseplate temperature tracking scaled at 10 mV/°C to allow the system controller to manage thermal profiles dynamically.

3. Environmental Tolerance and Load VSWR Parameters

Tactical field deployments expose RF components to impedance mismatches caused by damaged cabling or antenna decoupling. This broadband power amplifier module incorporates an output matching network that handles a load VSWR of 3:1 continuously across all load phases when operating at an output power up to 30 W.

Additionally, it survives an open or short circuit condition (VSWR of ∞:1) at any phase angle for up to 1 minute at 30 W output power. This window gives the control system enough telemetry tracking time via the current monitor line to detect the fault, pull Pin 1 low, and shut down the RF stage before catastrophic component failure occurs.

Frequently Asked Questions

Q1: What is the exact mathematical conversion for interpreting Pin 2’s current monitor analog voltage?

The current monitor output (Pin 2) translates current draw into voltage at 100 mV/A (which scales as 0.1 V/A). To determine the exact drain current (IDD) in amperes, use the formula: IDD (A) = Voltage (V) × 10. For instance, a typical current draw of 7 A at saturated output power outputs an analog telemetry voltage of 0.7 V (700 mV). A significant spike above this baseline indicates a load fault or high VSWR condition.

Q2: What are the primary RF connector types utilized on the MCW6018M47A module enclosure?

Both the RF Input and RF Output ports are equipped with standard SMA female connectors matched to a 50 Ω reference impedance. The module measures 190 × 90 × 25 mm, with the SMA connectors positioned on opposite sidewalls to facilitate inline coaxial routing and simplify cable management.

Q3: Can this GaN RF amplifier survive an antenna mismatch or open circuit condition?

The module is specified to withstand an infinite VSWR for up to one minute when operating at output powers up to 30 W, as defined in the product specifications. Operation beyond this rating is not covered by the specified ruggedness limits and should be avoided.