6–18 GHz 20 W Broadband GaN SSPA for Radar and EW Applications

The MCW6018M43A is a 6–18 GHz 20 W GaN solid-state power amplifier (SSPA) built for radar, electronic warfare (EW), and RF test systems. It delivers 20 W of typical saturated output power across the entire 6000 MHz to 18000 MHz operational band. Compared with legacy TWT or GaAs solutions, this compact module optimizes Size, Weight, and Power (SWaP) while maintaining a flat dynamic response across multi-octave sweeps.

Achieving flat gain response across multi-octave bandwidths remains a core challenge in microwave power design. Flat gain minimizes amplitude calibration errors during system sweeps. This prevents power drop-outs during rapid frequency hops. By integrating bare GaN die using chip-and-wire assembly, this broadband solid-state power amplifier minimizes package parasitics to achieve high power density.

SWaP Advantages and Microelectronic Assembly

The microelectronic architecture of the device provides distinct packaging advantages over standard discrete layouts:

• Chip-and-Wire Interconnects: Wire-bonding directly to bare GaN dies eliminates parasitic inductance and capacitance introduced by standard plastic packages. This ensures smooth, predictable gain response up to 18 GHz.
• Compact Form Factor: Measuring 150 × 90 × 25 mm with a maximum weight of 1.2 kg, the power stage reduces mechanical loading on mounting chassis and heatsinks in constrained subsystems.
• Solid-State Reliability: The semiconductor structure yields extended operating lifetimes compared to legacy vacuum-tube devices. This extends overall system maintenance intervals.

1. Electrical Performance and Pulsed Response Benchmarks

Operating from a nominal 28 VDC supply, the amplifier draws a typical current of 3.5 A at 20 W output.

Key RF metrics across the operating spectrum include:

• Power Gain: Achieves a typical power gain of 43 dB. High gain reduces the need for additional driver stages. This allows low-power synthesizers to drive the RF stage directly to full saturation.
• Fast Switching Response: Features a rapid RF switch control time (TON/OFF) of 2 µs typical (5 µs maximum). Fast switching enables precise pulsing and rapid RF blanking during radar and gated test operations.
• Impedance Matching and Spectral Purity: Input return loss is better than 10 dB into a standard 50 Ω RF network. Spurious signal outputs are suppressed to -60 dBc typical, while harmonics at 20 W output remain at -10 dBc typical.

2. Interface Pinout and Telemetry Diagnostics

A hybrid 7-pin D-Sub connector provides a standardized interface for primary DC power supply inputs, high-speed gating, and analog telemetry:

• Pins A1 / A2 (VDD / GND): Dedicated primary power feed supporting DC operating voltages from 26 V to 32 V (28 VDC nominal).
• Pin 1 (ENABLE): TTL logic high (3.3 V) enables the amplifier. An internal pull-low circuit keeps the RF stage disabled by default if the control line floats.
• Pin 2 (CURRENT MONITOR): Provides a real-time analog voltage output relative to drain current (IDD), scaled at 100 mV/A.
• Pin 3 (TEMP MONITOR): Outputs a real-time analog voltage proportional to baseplate temperature, scaled at 10 mV/°C to allow dynamic thermal monitoring.

3. Environmental Tolerance and Over-Temperature Protection

Practical RF deployments expose components to severe load 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 at 20 W output power.

The module also survives open- or short-circuit conditions (VSWR ∞:1) for up to one minute at 20 W output power. This specification applies across all load phase angles. Thermal management relies on an external heatsink (required, not supplied). An internal thermal switch monitors baseplate temperature. If the temperature reaches 85 °C, internal bias is disabled, and normal operation restores once the baseplate cools to 60 °C.

Frequently Asked Questions

Q1: What formula is used to calculate drain current from Pin 2’s analog voltage telemetry output?

Pin 2 translates current draw into voltage at 100 mV/A (0.1 V/A). To determine drain current (IDD) in amperes, use the conversion formula: IDD (A) = Voltage (V) × 10. For example, a typical 3.5 A current draw at 20 W output produces a 0.35 V (350 mV) analog telemetry reading.

Q2: Does the MCW6018M43A require an external heatsink for continuous operation?

Yes. The product datasheet specifies that an external heatsink is required for operation (not supplied with the module). The amplifier is rated for an operating temperature range of -20 °C to +60 °C. The thermal system must maintain the heatsink baseplate temperature below the 85 °C protection threshold to prevent thermal shutdown.

Q3: Can this 6–18 GHz GaN power amplifier survive an antenna mismatch or open circuit condition?

The module is specified to withstand an infinite VSWR (∞:1) for up to one minute when operating at output powers up to 20 W, as defined in the product specifications. Operation beyond this rating is not covered by specified ruggedness limits and should be avoided.