Inside Netgear WG121 USB Wlan

 

 

WG121

  • 54 Mbps Broadband Wlan USB2.0

  • 2400-2483 Mhz

  • 20 Mhz bandwich

  • 13 Channels

  • ~ 15db/m output power

  • bandwich 22 Mhz

  • channels 

 

 

 

1. small coax to antenna No.1 

2. antenna tab No.2

3. antenna diversity switch 
(337 2903 21)

4. way to TX

5. way to RX

6. balun 

7. Intersil ISL 3686AIR  
mixer, receiver, demodulator

(( can't find datasheed ))  

8. Intersil ISL 3084IR ???

9. Intersil ISL 3980IR  
power amplifier  

(( can't find datasheed ))

 

 


circuit diagramm rf part netgear WG121

Schematic Reference Type Description Info
U11 337 2903 21 pin switch for diversity  
U22   bandpass network 2.45Ghz / 50Mhz span.
U2 ISL3980IR power ampifier from Intersil max.22dbm
U14   rx balun  

This Wlan device offer such a bad range, so i draw this circuit of the rf section.

After that i start looking for main current going to the last rf stage. 

I took a shunt and read out the PA current.

But there's no difference between 3V or 4V. So I find some datasheeds from other PA’s 

and read a accurate automatic level control (ALC) function , using a detector circuit.

After a couple of hours I don’t found the right control tab. 

But this is not my last word. Why do manufactures build a wlan with 15dbm of TX power if 20dbm

Is possible in the europe FCC laws. This 5db will doubble the range !!! without hurt to somebody.

 

 

2.4 to2.4835MHz

  BLUETOOTH IEEE 802.11 IEEE 802.11 b IEEE 802.11 g IEEE 802.11 a
modulation FHSS DSSS DSSS DSSS  
frequency 2.4 - 2.483 Ghz 2.4 - 2.483 Ghz 2.4 - 2.483 Ghz 2.4 - 2.483 Ghz 5 Ghz
datarate 1 M/bit 2 M/bit 11 M/bit 54 M/bit  
netto rate     ~4-5 M/bit ~23 M/bit ~23 M/bit
TX power 1 , 25 or 100mW 100mW 100mW 100mW 1000mW
bandwich 1 Mhz 22 Mhz 22 Mhz 22 Mhz  
channels EU 79 13 13 13 12