WLAN_semi_Ralink--free

WLAN_semi_RalinkLu°ì

RF]-p°DPD

Jin Luo
Jin_luo@ralinktech.com.tw

September 29, 2003

The Concept of RF System

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Heterodyne Receiver Structure
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Antenna Band Select Filter Image Reject Channel Select Filter RF Mixer Filter (SAW)

IF VCO
LNA VGA

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RF VCO

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hAdvantage
-Good Sensitivity (Good Image Suppression) -Good Channel Selectivity -Most of today’s RF System

hDisadvantage
-Need many off chip Components -Large Chip size -High Power Consumption

Homodyne Receiver Structure (Zero-IF)
Channel Select Filter RF Mixer

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Antenna VGA Preselect Filter

A D

RF VCO
LNA

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hAdvantage
-No Image Filter Required -No need 50 matching of LNA output -No need IF Filter (Low Cost) -Monolithic Integration