A 1.2V fully integrated RSSI applied for wireless sensor networks（WSNs）is designed.The basic theory of logarithmic amplifier is presented

DC offset cancellation circuit is improved and using vibration feedback to make clipper amplifier part easy to be fully integrated.Full-wave rectifier circuit is also improved

which can work in low voltage

lower power consumption

and greatly improves the process and temperature stability.Use 0.18 μm CMOS technology

simulation result shows that when using 1.2V supply voltage

direct current（DC）of RSSI is less than 0.6 mA input dynamic range of the limiter is-85

-

10 dBm

and RSSI linear error is within ±0.5 dB for 2 MHz input frequency（IF）application.