Apparatus for controlling sensitivity by using digital gating in receiver and receiver with the same

Abstract

Disclosed is a wireless communication system, more particularly, a receiver and a chipset for DSRC. A receiver includes: a low noise amplifier (LNA) amplifying a received radio (RF) signal while minimizing amplification of noise included in the received RF signal; a mixer down-converting a frequency of an output signal of the LNA to output an intermediate frequency (IF) signal; a frequency synthesizer generating and outputting a frequency signal for the frequency-down conversion of the mixer to the mixer; a bandpass filter passing a necessary band of a channel in an output signal of the mixer; a log amplifier amplifying an output signal of the bandpass filter in log scale and outputting a received signal strength indicator of an output signal of the bandpass filter; a detector comparing an output of the log amplifier with a predetermined binary threshold value, outputting a first binary signal when the output of the log amplifier is less than the predetermined binary threshold value, and outputting a second binary signal when the output of the log amplifier is equal to or greater than the predetermined binary threshold value; a switch serially connected with an output terminal of the detector; and a switch controller comparing the received signal strength indicator of the output signal of the log amplifier with an RSSI threshold, opening the switch when the received signal strength indicator is less than the RSSI threshold, and closing the switch when the received signal strength indicator is equal to or grater than the RSSI threshold.

What is claimed is: 
     
       1. A receiver comprising:
 a low noise amplifier (LNA) amplifying a received radio (RF) signal while minimizing amplification of noise included in the received RF signal; 
 a mixer down-converting a frequency of an output signal of the LNA to output an intermediate frequency (IF) signal; 
 a frequency synthesizer generating a predetermined frequency signal for the frequency-down conversion of the mixer and outputting the predetermined frequency signal to the mixer; 
 a bandpass filter passing a necessary band of a channel in an output signal of the mixer; 
 a log amplifier amplifying an output signal of the bandpass filter in log scale and outputting a received signal strength indicator of an output signal of the bandpass filter; 
 a detector comparing an output of the log amplifier with a predetermined binary threshold value, outputting a first binary signal when the output of the log amplifier is less than the predetermined binary threshold value, and outputting a second binary signal when the output of the log amplifier is equal to or greater than the predetermined binary threshold value; 
 a switch serially connected with an output terminal of the detector; and 
 a switch controller comparing the received signal strength indicator of the output signal of the log amplifier with an RSSI threshold, opening the switch when the received signal strength indicator is less than the RSSI threshold, and closing the switch when the received signal strength indicator is equal to or grater than the RSSI threshold. 
 
     
     
       2. The receiver according to  claim 1 , wherein the switch controller includes:
 an analog-to-digital converter converting the received signal strength indicator into a digital signal; 
 an RSSI threshold generator generating the RSSI threshold; and 
 a comparator comparing the received signal strength indicator with the RSSI threshold, and opening or closing the switch according to the comparison result. 
 
     
     
       3. The receiver according to  claim 2 , wherein the RSSI threshold generator includes:
 a temperature sensor measuring an ambient temperature; and 
 a look-tip table storing the RSSI threshold corresponding to the ambient temperature measured by the temperature sensor. 
 
     
     
       4. The receiver according to  claim 3 , wherein the receiver alternately operates in a signal reception mode receiving signals and a signal non-receiving mode receiving no signals, and the temperature sensor measures the ambient temperature once each time the signal reception mode starts. 
     
     
       5. An amplitude shift keying (ASK) receiver for designated short range communication (DSRC) receiving and converting a DSRC radio frequency (RF) signal of a 5.8 GHz band into a digital signal, comprising:
 a low noise amplifier (LNA) amplifying the received DSRC RF signal while minimizing amplification of noise included in the received DSRC RF signal; 
 a mixer down-converting a frequency of an output signal of the LNA to output an intermediate frequency (IF) signal; 
 a frequency synthesizer generating and outputting a frequency signal for the frequency-down conversion of the mixer to the mixer; 
 a bandpass filter passing a necessary band of a channel in an output signal of the mixer; 
 a log amplifier amplifying an output signal of the bandpass filter in log scale; and 
 a detector comparing an output of the log amplifier with a predetermined binary threshold value, outputting a first binary signal when the output of the log amplifier is less than the predetermined binary threshold value, and outputting a second binary signal when the output of the log amplifier is equal to or greater than the predetermined binary threshold value, 
 wherein the ASK receiver for DSRC is formed in one-chip by a complementary metal-oxide semiconductor (CMOS) process and the intermediate frequency is a 10 MHz band. 
 
     
     
       6. A receiver comprising:
 a low noise amplifier (LNA) amplifying a received radio (RF) signal while minimizing amplification of noise included in the received RF signal;   a mixer down-converting a frequency of an output signal of the LNA to output an intermediate frequency (IF) signal;   a frequency synthesizer generating a predetermined frequency signal for the frequency-down conversion of the mixer and outputting the predetermined frequency signal to the mixer;   a bandpass filter passing a necessary band of a channel in an output signal of the mixer;   a log amplifier amplifying an output signal of the bandpass filter in log scale and outputting a received signal strength indicator of an output signal of the bandpass filter;   a controller for comparing the received signal strength indicator of the output signal of the log amplifier with an RSSI threshold; and   a switch for selectively forwarding the output of the log amplifier based on the comparing results of the controller.   
     
     
       7. The receiver according to claim 6, wherein the controller includes:
 an analog-to-digital converter converting the received signal strength indicator into a digital signal;   an RSSI threshold generator generating the RSSI threshold; and   a comparator comparing the received signal strength indicator with the RSSI threshold, and opening or closing the switch according to the comparison result.   
     
     
       8. The receiver according to claim 7, wherein the RSSI threshold generator includes:
 a temperature sensor measuring an ambient temperature; and   a look-tip table storing the RSSI threshold corresponding to the ambient temperature measured by the temperature sensor.   
     
     
       9. The receiver according to claim 8, wherein the receiver alternately operates in a signal reception mode receiving signals and a signal non-receiving mode receiving no signals, and the temperature sensor measures the ambient temperature once each time the signal reception mode starts. 
     
     
       10. An amplitude shift keying (ASK) receiver for designated short range communication (DSRC) receiving and converting a DSRC radio frequency (RF) signal of a 5.8 GHz band into a digital signal, comprising:
 a low noise amplifier (LNA) amplifying the received DSRC RF signal while minimizing amplification of noise included in the received DSRC RF signal;   a mixer down-converting a frequency of an output signal of the LNA to output an intermediate frequency (IF) signal;   a frequency synthesizer generating and outputting a frequency signal for the frequency-down conversion of the mixer to the mixer;   a bandpass filter passing a necessary band of a channel in an output signal of the mixer;   a log amplifier amplifying an output signal of the bandpass filter in log scale; and   a controller comparing an output of the log amplifier with a predetermined binary threshold value, outputting a first binary signal when the output of the log amplifier is less than the predetermined binary threshold value, and outputting a second binary signal when the output of the log amplifier is equal to or greater than the predetermined binary threshold value,   wherein the ASK receiver for DSRC is formed in one-chip by a complementary metal-oxide semiconductor (CMOS) process and the intermediate frequency is a 10 MHz band.