Difference between revisions of "SUNHANS WiFi Amplifier"

Revision as of 20:26, 14 October 2015

I picked up a "Easysmx SUNHANS SH-2500 2500mW wireless signal repeater 34dBm WiFi booster" from Amazon for a future project.

My future project is going to be battery powered, and used with IEEE 802.15.4 signals. I had to do some investigation to see if it is suitable for my project.

The module is two piece all metal construction. Disassembling it required a Torx screw driver. It is not possible to take out the PCB, because the SMA connectors are mounted directly to the case and its pins are soldered to the PCB directly.

Note that the metal housing is very thick and would act as a great Faraday cage. Awesome.

Inside is a pretty obvious high powered RF front end circuit. On the high powered end there is a chip that is clearly a Skyworks SKY13299-321LF, which is a high power RF switch rated for 7W signals. On the low powered end, there was a SOT-23-6 footprint chip that is a RF switch (many possible part numbers, but SKY13270-92LF is a close match).

On the transmit path, there's a Skyworks SKY65174-21 RF amplifier with 35 dB gain and a power amplifier with linear output of +26 dBm. This is the muscle of the circuit. This chip also a the RF signal detection feature which is connected to the RF switches through a network of MOSFETs.

At this point, I know that there isn't much I can do to adjust the output power without putting in a physical attenuator somewhere, because the amplifier chip doesn't have any interface to adjust its own output power. But if I required to manually operate the RF switches, I know there's one easily accessible signal that can operate all the switches.

The circuit is shipped with a 12V 2A wall wart. But I was planning on using a 7.4V li-po battery pack. Luckily I found a TPS54320 chip, which is a DC/DC switching step-down converter, and its feedback circuit is configured to output 5V. The input range for this chip is 4.5V to 17V, so I am pretty safe using my 7.4V battery pack. The 5V output from the converter is also fed into a SOT-223 footprint LDO voltage regulator that outputs 3.3V