Radio frequency front-end based on high-intermediate frequency superheterodyne and zero intermediate frequency structure

Abstract

The invention discloses a radio frequency front-end based on the high-intermediate frequency superheterodyne and zero intermediate frequency structure, which includes a transmitting module and a receiving module, wherein, the receiving module includes the following devices connected in turn with each other: a transceiving antenna, a low-pass filter, a superheterodyne unit, an IF band-pass filter, a zero-IF unit, a analog-to-digital converter and a digital baseband module of which the output is communicated with the transmitting module. The zero-IF unit includes the following devices which are also connected in turn with each other: a zero-IF mixer, an active low-pass filter and a variable gain operational amplifier of which the output is communicated with the input of the ADC; the inputs of the zero-IF mixer are communicated with the output of the IF band-pass filter and the second LO respectively. The present invention avoids the image interference, improves the system integration and decreases the system consumption.

What is claimed is: 
     
       1. A radio frequency (RF) front-end based on a high-intermediate frequency superheterodyne and zero intermediate frequency (zero-IF) structure comprising a transmitting module and a receiving module, said receiving module comprising: a transceiving antenna ( 1 ), a low-pass filter ( 3 ) connected to said transceiving antenner, a superheterodyne unit ( 4 ) connected to said low-pass filter, an IF band-pass filter ( 5 ) connected to said superheterodyne unit, a zero-IF unit ( 6 ) connected to said IF band-pass filter, a analog-to-digital converter (ADC) ( 7 ) connected to said zero-IF unit and a digital baseband (DBB) module ( 8 ) connected to said analog-to-digital converter at one end and connected to said transmitting module ( 9 ) at another end, wherein said superheterodyne unit having a first local oscillator ( 43 ) and said transmitting module having a third local oscillator ( 94 ). 
     
     
       2. The radio frequency front-end according to the  claim 1 , wherein the transceiving antenna ( 1 ) communicates with the low-pass filter ( 3 ) by wireless switch ( 2 ). 
     
     
       3. The radio frequency front-end according to the  claim 1 , wherein the superheterodyne unit ( 4 ) comprises a superheterodyne mixer ( 42 ), the inputs of which are communicated with a low noise amplifier (LNA) ( 41 ) and the first local oscillator (LO) ( 43 ) respectively; and the output of the superheterodyne mixer ( 42 ) is communicated with the input of the IF band-pass filter ( 5 ); wherein, the input of the LNA ( 41 ) is communicated with the output of the low-pass filter ( 3 ). 
     
     
       4. The radio frequency front-end according to the  claim 3 , wherein the tuning range of the first LO ( 43 ) ranges from 1.25 GHz to 2.35 GHz. 
     
     
       5. The radio frequency front-end according to the  claim 1 , wherein the zero-IF unit ( 6 ) comprises the following devices which are connected with each other in turn: a zero-IF mixer ( 61 ), an active low-pass filter ( 63 ) and a variable gain operational amplifier ( 64 ) of which an output is communicated with the input of the ADC ( 7 ); the inputs of the zero-IF mixer ( 61 ) are communicated with the output of the IF band-pass filter ( 5 ) and a second LO ( 62 ). 
     
     
       6. The radio frequency front-end according to the  claim 1 , wherein the transmitting module ( 9 ) comprises the follows which are connected with each other in turn: a modulation mixer ( 91 ), a power amplifier (PA) driving circuit ( 92 ) and a power amplifier ( 93 ); the inputs of the modulation mixer ( 91 ) are communicated with the output of the DBB module ( 8 ) and the third LO ( 94 ); and the output of the power amplifier ( 93 ) is communicated with the wireless switch ( 2 ) of the transceiving antenna ( 1 ). 
     
     
       7. The radio frequency front-end according to the  claim 1 , wherein the output of the superheterodyne unit ( 4 ) has a fixed-frequency of 2.45 GHz.