What are the standard brick converter sizes?

The Distributed-power Open Standards Alliance (DOSA) defines four standard brick sizes: eighth-brick (22.9 × 58.4 mm, 25-100 W), quarter-brick (36.8 × 58.4 mm, 50-400 W), half-brick (57.9 × 61.0 mm, 200-700 W), and full-brick (116.8 × 61.0 mm, 500-1500 W). All have standardized pinouts and mounting holes, enabling multi-sourcing across manufacturers without board redesign.

Why are brick converters used in phased array power distribution?

Phased arrays require distributed power with tight voltage regulation at each T/R module cluster. Brick converters provide galvanic isolation between the bulk DC bus (typically 270 VDC in military aircraft or 48 VDC in telecom) and the local 28 V or 50 V PA drain supply. The isolation prevents ground loop currents between array elements and simplifies fault management. A 64-element sub-array might use one half-brick converter to generate 28 V at 15 A for the GaN PA cluster, with point-of-load regulators providing additional 5 V and 3.3 V rails for digital beamformer ICs.

What efficiency do modern brick converters achieve?

Modern GaN-based brick converters achieve 95-97% peak efficiency, compared to 90-93% for silicon MOSFET designs of a decade ago. At a 500 W output, the difference between 93% and 96% efficiency is 15 W less heat dissipation, which is significant in enclosed RF systems where thermal management is already challenging. The highest efficiencies are achieved at 40-80% load; efficiency drops to 88-92% at 10% load due to fixed switching losses.

What is a Brick Converter? | Isolated DC-DC Module

Definition & Function

A brick converter is a packaged, isolated DC-DC power supply module built to standardized form factors defined by the Distributed-power Open Standards Alliance (DOSA). These modules convert a high-voltage DC bus (typically 28, 48, or 270 VDC) into regulated lower-voltage outputs needed by RF subsystems: 28 V or 50 V for GaN PA drain supplies, 12 V for analog circuits, and 5/3.3 V for digital control electronics. The "brick" designation refers to the rectangular package shape and standardized pinout that enables drop-in replacement across multiple manufacturers.

In RF system architectures, brick converters serve as the intermediate bus converter (IBC) stage between the system's bulk power supply and point-of-load regulators near the RF devices. The galvanic isolation they provide prevents ground loops between distributed RF modules, blocks common-mode noise from propagating across the power bus, and enables the use of different grounding strategies on the primary and secondary sides. For military and aerospace RF systems operating from MIL-STD-704 270 VDC aircraft buses, the brick converter is often the only practical way to generate the regulated 28-50 V rails needed for GaN power amplifiers.

Key Specifications

Efficiency:

η = P_out / P_in × 100%

Modern GaN-based: 95-97% peak | Si MOSFET: 90-93% peak

Power Dissipation:

P_loss = P_out × (1/η − 1)

500 W at 96%: P_loss = 500 × 0.042 = 20.8 W

Brick Form Factor Comparison

Form Factor	Dimensions (mm)	Power Range	Peak Efficiency	Typical RF Application
Eighth Brick	22.9 × 58.4	25-100 W	93-95%	LNA bias, digital control
Quarter Brick	36.8 × 58.4	50-400 W	94-96%	Single PA module
Half Brick	57.9 × 61.0	200-700 W	95-97%	T/R module cluster
Full Brick	116.8 × 61.0	500-1500 W	95-97%	Sub-array power

Practical Application

In an X-band AESA radar sub-array with 64 GaN T/R modules, each dissipating 8 W at 50 V drain bias, the total PA power demand is 64 × 8 W = 512 W. A single half-brick converter rated at 600 W converts the 270 VDC aircraft bus to 50 V with 96% efficiency, dissipating only 21.3 W of heat. This is mounted on the cold plate directly behind the sub-array panel. Two additional quarter-brick converters generate 5 V at 80 W for the digital beamformer FPGAs and 3.3 V at 30 W for the phase shifter control ASICs. The standardized DOSA pinout allows the system integrator to second-source all three converters from at least three manufacturers without PCB modifications.

Frequently Asked Questions

What are the standard brick sizes?

DOSA defines eighth (22.9×58.4 mm, 25-100 W), quarter (36.8×58.4 mm, 50-400 W), half (57.9×61.0 mm, 200-700 W), and full brick (116.8×61.0 mm, 500-1500 W) with standardized pinouts for multi-sourcing.

Why use brick converters in phased arrays?

Galvanic isolation prevents ground loops between array elements. They convert bulk 48/270 VDC bus to local 28-50 V PA rails. A 64-element sub-array typically uses one half-brick for PA power plus quarter-bricks for digital rails.

What efficiency do modern bricks achieve?

GaN-based designs reach 95-97% peak at 40-80% load. At 500 W, the 3% improvement over older Si designs saves 15 W of heat dissipation, which is significant in enclosed RF enclosures.

Brick Converter