Ultra-low-power series voltage regulator for passive microwave RFID transponders

In this paper we present a series voltage regulator for long distance passive RFID transponders, operating in the 868/916 MHz and 2.45 GHz ISM frequency ranges. The circuit has been implemented in a 0.35/spl mu/m BiCMOS technology. Measurements show that the voltage regulator can provide a regulated voltage of 0.6 V, for an output current from 0 to 5 /spl mu/A, with a quiescent current of only 34 nA, a minimum voltage drop of 30 mV and an output resistance of 100 /spl Omega/. Measurements also show a very good PSRR, particularly in DC and at the operating frequency of the tag-reader system, where it is smaller than -58 dB and -54 dB, respectively.