RF Workings of a Wifi Receiver

[Fischer777]

I am curious to know how the RF front end of a Wifi receiver works. From my understanding, most RF receivers have to use networks of various oscillators, mixers, and filters to select a given frequency and remain insensitive to undesired signals at different frequencies, and I suspect that WiFi is no different (although I could be wrong). However, Wifi chips are small and to my knowledge don't contain any elements usually used to implement oscillators and filters (like inductors and capacitors). So my question is, how are Wifi devices able to implement those systems? I guess this question doesn't apply specifically to Wifi, but any device that uses a integrated receiver system.

 

[meBigGuy]

Here is a typical RF wifi chip. It requires a companion digital MAC/PHY chip
http://www.maximintegrated.com/en/products/comms/wireless-rf/MAX2830.html

 

[davenn]

good response, mebigguy

and I just had to post that block diag here for ease of viewing ...

To the OP, so you can see that all the physically larger components caps and inductors are mounted on the circuit board outside of the chip
I can see at least 2 caps on the inside ( probably REALLY small values)

This is typical of a lot of LSI ( Large Scale Integration) chips for all sorts of transmitters and or receivers 2-waqy radios, TV/ FM Broadcast receivers
WiFi, Cellphones etc etc

Dave

 

[Windadct]

One reason I like arduino - all of the common shields are open source -- here is the complete schematic of the WiFi shield, so it shows the external components Davenn mentioned.

 

[meBigGuy]

You can buy (if you are an OEM) 2.4GHz wireless audio systems with the complete system (RF/PHY/MAC/ADC/DAC/AMP/Battery charger/USB, etc etc) on a single 3.3V chip. External capacitors and flash are about it for external components.

 

[Fischer777]

Thanks for the info guys. I guess my question pertains specifically to what appear to be the variable filters on the diagrams. All filters I'm familiar with need some reactive component, like an inductor or capacitor. Is some technique used to build the reactive elements in the the chip itself, or does it use the external capacitors for this purpose. Or, is there a method of implementing such filters without the use of reactive components?

 

[davenn]

I guess my question pertains specifically to what appear to be the variable filters on the diagrams. All filters I'm familiar with need some reactive component, like an inductor or capacitor. Is some technique used to build the reactive elements in the the chip itself, or does it use the external capacitors for this purpose. Or, is there a method of implementing such filters without the use of reactive components?

That is just a block diagram that is shown above. It just shows the significant components, there are likely to be many more if you could see the full schematic diagram

 

[meBigGuy]

You can build inductors and capacitors on chip.