2. RSSI无线信号强度指示的意义（mW和dBm） 
3. SMT规范 
4. Input Offset Voltage Offset voltage is required across the operational amplifier's two input terminals in order to drive the output voltage to zero and is also related to the mismatches in bias input current. The ideal operational amplifier would have no input offset voltage. The input offset voltage exists in operational amplifiers due to imperfections in the differential amplifier which constitutes the input stage of the vast majority of these devices.
Input offset voltage brings about two problems:
•Operational amplifier's have high voltage gain which virtually assures that the op-amp's output will result in saturation if it is used without negative feedback.
•In a closed loop negative feedback configurations the operational amplifier's input offset voltage is amplified along with the signal which may pose a problem if precision high direct current (DC) amplification is needed or if the input signal is exceptionally small.