Low power ASK modulator based on direct injection-locked current reuse VCO in 130-nm CMOS technology for high data rate RFID applications

A low power consumption Amplitude Shift Keying (ASK) modulator employing current reuse cross-coupled (CRC) LC-VCO topology and direct injection locking (IL) technique at 10.5-GHz frequency is presented in this paper. The modulator consumes 864 mu W with a DC supply of 1.2 V drawing an average current of 720 mu A. The differential VCO is composed of a PMOS-NMOS pair in stacked series cross-coupled connection enabling current reuse which results in reduction of the average current drawn from the power source. For comparison, the ASK modulator is also realized with conventional cross-coupled (CC) topology using NMOS pair. Both circuit approaches are carried out in GF 130-nm CMOS technology and the post-layout simulation results of 0.5 x 0.5 mm(2) integrated circuits (ICs) show that the CRC topology consumes less power and half of the average current compared to CC topology. Owing to low power requirements, the CRC ASK modulator can be used in self-powered active Radio Frequency Identification (RFID) tag transmitters for higher data rates.