Inside the EDUP EP-AB003 2.4GHz Amplifier

Introduction

EDUP makes a powerful, but cheap WiFi amplifier - the EP-AB003. These can be found on eBay or Amazon, with direct shipping from Shenzen. They're around $50.

Assembled unit

Disassembled unit

Analysis

Overview

There's a single PCB. Additionally, it looks like the amplifier is using the case as ground, as the coaxial connectors are not soldered directly to the PCB. The coax port on the left-side goes to the access point, and the coax port on the right-side go to and from the antenna.

Power section

Amplifiers are notoriously sensitive to power supply fluctuations. Externally, the amplifier is fed by a 12v 2amp wall wart. Internally, the AP003 uses a DC-DC switching regulator to convert the external voltage down to something lower. Power is fed to the amplifier at the top-right corner of the PCB through a barrel-connector. The power supply subsection takes up approximately the top 1/4 of the PCB. The power supply consists of a few front-end capacitors, an inductor, a switching-controller that pulses current through the inductor, and some back-end capacitors to filter the output. This means that the amplifier operates on voltage lower than the 12-volt input, but also that it may be sensitive to the quality of capacitors used in the power supply, as lower-quality(high ESR) capacitors may let noise slip through.

Amplification

Following the center-conductor from the left coax-port, the signal splits through an RF switch between the middle section and the lower section.

The middle section appears to be the transmitter amplifier. Amplification is done in two parallel stages, then combined in the chip just left of the right coax-port.

The lower section appears to be the recieve amplifier, as well as the detector that automatically switches the amplifier direction.

Thermal Dissipation

At a few spots on the PCB, especially near the right coax-port's combiner, silicone heatsink putty is leaking through some of the vias on the board. So the heat goes out of the back of the PCB, which is the front of the amplifier. If I ever need more cooling, I know where to add the heatsink.