A Fast Settling Phase Modulator for Outphasing Transmitters in 65-nm CMOS

Abstract

We present a phase modulator architecture with very fast settling time for use in high data-rate outphasing transmitters. The proposed design utilizes the phase-shifting capabilities of a resonant tank and the ability to separately control the circuit properties via its components. A prototype in 65-nm CMOS achieves 9 bits of effective resolution, with a fast settling time of less than five carrier cycles to within 1 . The circuit is also tested as a standalone transmitter showing an error vector magnitude of less than 5% for 8-PSK modulation at maximum data rate of 240 Mb/s, meeting the Federal Communications Commission requirements for operation at the medical implant communication services band. Index Terms-CMOS integrated circuits, phase modulation, phase shifters, RF integrated circuits.0018-9480

Multilevel outphasing power amplifier system with a transmission-line power combiner

“…More digital-intensive implementation has been enabled by digital, often CORDIC-based SCSs operating at baseband [56,57]. The phase modulators have commonly been implemented using variations of I/Q-based modulation [58][59][60] or other analog-intensive methods [61,62], but the overall portion of digital circuitry can be better maximized with delay-based digital phase modulators [63,64]. Unlike Cartesian and polar transmitters, the outphasing architecture relies entirely on time-mode signaling, which makes it an appealing option for digitalintensive implementation with low-voltage CMOS technologies.…”

“…Much of the published research on outphasing has focused on either PA design and power combination [70][71][72][73][74][75][76][77], or modulators without PAs [59][60][61]64]. In contrast to Cartesian and polar architectures, very few fully integrated outphasing transmitters including PAs have been reported [63].…”