提高射頻前端AMI前端系統(tǒng)的靈敏度

　　正在部署的基于RF的先進(jìn)計量基礎(chǔ)設(shè)施（AMI）系統(tǒng)的數(shù)量正在穩(wěn)步增加。這種AMI系統(tǒng)的射頻前端必須具有很好的靈敏度，同時證明它不受來自不同RF應(yīng)用的干擾。這些干擾既不妨礙數(shù)據(jù)傳輸，也不可能接收測量數(shù)據(jù)。

　　圖1顯示了一個基于射頻的AMI系統(tǒng)中典型的收發(fā)器設(shè)計。

　　The transmitter section of the AMI transceiver consists of a balun which transforms the differential signal coming from the RF output of the IC to a single ended signal. After passing through the SPDT switch and the PA， the RF modulated signal is filtered by a SAW filter. This SAW filter suppresses the harmonics as well as the spurious emission generated by the internal phase locked loop （PLL） of the Transceiver IC. The antenna then transmits the data to the meter.

　　The receiving path is where the trigger signal for data transmission is received. This consists of a SAW filter right after the antenna， a second SAW filter for increasing selectivity， and the balun which transforms the unbalanced signal into a balanced one.