A Wideband 2x13-bit All-Digital I/Q RF-DAC

Alavi, S.M.; Staszewski, R.B.; De Vreede, L.C.N.; Long, J.R.

doi:doi:10.1109/TMTT.2014.2307876

A Wideband 2x13-bit All-Digital I/Q RF-DAC

Title

A Wideband 2x13-bit All-Digital I/Q RF-DAC

Author

Alavi, S.M.
Staszewski, R.B.
De Vreede, L.C.N.
Long, J.R.

Faculty

Electrical Engineering, Mathematics and Computer Science

Department

Microelectronics & Computer Engineering

Date

2014-03-10

Abstract

This paper presents a wideband 2 13-bit in-phase/quadrature-phase (I/Q) RF digital-to-analog converter-based all-digital modulator realized in 65-nm CMOS. The isolation between I and Q paths is guaranteed employing 25% duty-cycle differential quadrature clocks. With a 1.3-V supply and an on-chip power combiner, the digital I/Q transmitter provides more than 21-dBm RF output power within a frequency range of 1.36–2.51 GHz. The peak RF output power, overall system, and drain efficiencies of the modulator are 22.8 dBm, 34%, and 42%, respectively. The measured static noise floor is below 160 dBc/Hz. The digital I/Q RF modulator demonstrates an IQ image rejection and local oscillator leakage of 65 and 68 dBc, respectively. It could be linearized using either of the two digital predistortion (DPD) approaches: a memoryless polynomial or a lookup table. Its linearity is examined using single-carrier 4/16/64/256/1024 quadrature amplitude modulation (QAM), as well as multi-carrier 256-QAM orthogonal frequency-division multiplexing baseband signals while their related modulation bandwidth can be as high as 154 MHz. Employing DPD improves the third-order intermodulation product (IM3) by more than 25 dB, while the measured error vector magnitude for a “single-carrier 22-MHz 64-QAM” signal is better than 28 dB.

Subject

Balun
class-E power amplifier
digital power amplifier (DPA)
digital predistortion (DPD)
digital-to-RF-amplitude converter (DRAC)
in-phase/quadrature-phase (I/Q) modulator
MOS switch
RF digital-to-analog converter (RF-DAC)
transformer
transmitter (TX)