A low power high sensitivity RF power detector for multi-mode active tags

This paper presents a low power high sensitivity RF power detector (PD) for multi-mode active tags. To achieve low power consumption and large detection range, two-branch common-source-type MOSFET transistors biased in subthreshold region are used. This power detector produces the mode-enabled signals to the multi-mode active tag according to the different received RF power. Therefore, the multi-mode active tag can be switched into idle mode, active mode, semi-passive mode and passive mode with proper power consumption. The PD is fabricated in a 0.13-μm mixed signal CMOS process with power consumption of 216nW in idle state. Measured result at 900MHz shows that the PD features a sensitivity of -51dBm. The active mode enabled signal is produced when the received RF power is located between -51dBm and -25dBm. The semi-passive mode enabled signal is produced when the received RF power is located between -25dBm and -15dBm and the passive mode enabled signal is produced when the RF power is beyond -15dBm.