how to improve receiver sensitivity



1. A smaller bandwidth could be used. This is usually fixed by IF requirements.
2. The loss in the preselect filter or switch could be reduced. For example,
the LNA could be placed in front of one or both of these components.
3. The noise figure of the LNA could be improved.
4. The LNA gain could be increased reducing the effect of the mixer on
the system NF.
5. A lower NF in the mixer would also improve the system NF.
6. If a lower SNR for the required BER could be tolerated, then this
would also help.

Re: how to improve receiver sensitivity

With external LNA there is a good method to improve receiver sensitivity

Improving Receiver Sensitivity with External LNA

Abstract: This application note presents the system level trade-offs involved in adding a low-noise amplifier (LNA) to a remote keyless entry (RKE) receiver. The system’s sensitivity improves 3.77dB, but the third order intercept degrades by 15dB.

The sensitivity specifications indicates how well a receiver will capture weak signals. It is a key specification becauseand it directly affects the range of the system.

In many remote keyless entry (RKE) and tire pressure monitoring (TPM) designs, the manufacturer will quote the sensitivity of the receiver (dBm) as a means to differentiate the system from a competitor’s. Other receiver parameters such as noise figure, intermodulation distortion, dynamic range or even power consumption are sometimes relegated in importance because of the importance that consumers place on sensitivity and range.

One way to improve a system’s sensitivity is to add gain by connecting an external LNA. Or — is it that simple?

more details

http://www.maxim-ic.com/appnotes.cfm/an_pk/1836

Re: how to improve receiver sensitivity

The receiver has a minimum received power threshold that the received signal must have to achieve certain bit rate. If the received signal power is lower than the threshold, the maximum bit rate could be decreased, impacting performance. Receiver sensitivity depends both on RF and baseband design.



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