A 6-bit phase shifter for UHF RFID application

This paper presents a 6-bit phase shifter for UHF RFID application. An unbalanced H-network attenuator is adopted to improve the linearity for handling the large cancelling signal and simultaneously achieve impedance matching. A newly-modified encoding, which can reduce three quarters of digital standard cells, is proposed. Based on a standard 0.18-μm CMOS technology, simulated results illustrate that the rms phase error and gain error are less than 0.21° and 0.3 dB over the 0.8-1 GHz band. The input P1dB is large than 10 dBm at all phase-control states. The total current consumption is 1.0 mA with a 3.3 V supply voltage.