How Does a Wifi Receiver Implement RF Systems Without Traditional Components?

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Discussion Overview

The discussion centers on the implementation of RF systems in WiFi receivers, particularly focusing on how these devices manage to function without traditional components like inductors and capacitors. Participants explore the design and integration of RF front ends in compact WiFi chips, considering both theoretical and practical aspects.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Exploratory

Main Points Raised

  • One participant questions how RF front ends in WiFi receivers operate without traditional components typically used in RF systems, such as oscillators, mixers, and filters.
  • Another participant provides a link to a typical RF WiFi chip, noting its requirement for a companion digital MAC/PHY chip.
  • A participant mentions that larger components like capacitors and inductors are often mounted on the circuit board outside of the chip, suggesting that some small capacitors may be integrated within the chip.
  • There is a reference to open-source Arduino shields that include schematics showing external components used in WiFi systems.
  • One participant notes that complete wireless systems can be integrated onto a single chip, with only a few external components like capacitors and flash memory.
  • A participant expresses curiosity about the variable filters in the diagrams, questioning whether reactive components are built into the chip or if external components are used for filtering.
  • Another participant asserts that inductors and capacitors can be built on-chip, implying that this may address the concerns raised about traditional filtering methods.

Areas of Agreement / Disagreement

Participants express varying views on the implementation of reactive components in WiFi receivers, with some suggesting that external components are necessary while others propose that these elements can be integrated within the chip. The discussion remains unresolved regarding the specifics of how filtering is achieved without traditional components.

Contextual Notes

The discussion highlights the complexity of RF system design in compact devices and the potential for integrated solutions, but lacks detailed technical specifications or consensus on the methods used for filtering.

Fischer777
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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.
 
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good response, mebigguy

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

5367.gif
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
 
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.
 
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.
 
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?
 
Fischer777 said:
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
 
You can build inductors and capacitors on chip.
 

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