A Low-Current Digitally Predistorted Direct-Conversion Transmitter With 25% Duty-Cycle Passive Mixer

Author

Collados, Manel ; Hongli Zhang ; Tenbroek, Bernard ; Hsiang-Hui Chang

Author_Institution

MTK Wireless Ltd., West Malling, UK

Volume

62

Issue

4

fYear

2014

fDate

Apr-14

Firstpage

726

Lastpage

731

Abstract

A low-current direct-conversion transmitter (TX) is obtained by combining an efficient single-balanced 25% duty-cycle passive mixer with a low-bias single-ended driver. The nonlinearity of such architecture is aggravated by strong harmonics at the mixer output folding down to the fundamental frequency due to driver nonlinearity. To address this, a baseband mathematical model of the passive mixer plus nonlinear driver is derived. Then, based on this model, a novel digital-predistortion approach is disclosed. Implemented in 40-nm CMOS, the modulator and driver combined consume 45 mW when delivering a +3-dBm Release 99 WCDMA signal with 0.9% error vector magnitude (EVM) and -59-dBc adjacent-channel leakage power ratio (ACLR). In long-term evolution (LTE) mode, the TX delivers +0-dBm 10-MHz LTE 16QAM with -53-dBc ACLR and 1.2% EVM.

Keywords

CMOS integrated circuits; Long Term Evolution; code division multiple access; driver circuits; low-power electronics; mixers (circuits); nonlinear network analysis; power amplifiers; quadrature amplitude modulation; radio transmitters; 16QAM; CMOS integrated circuit; LTE; WCDMA signal; baseband mathematical model; digitally predistorted direct conversion transmitter; long term evolution; low bias single ended driver; low current transmitter; mixer output harmonics; nonlinear driver; passive mixer; power 45 mW; size 40 nm; Harmonic analysis; Mathematical model; Mixers; Modulation; Nonlinear distortion; Polynomials; Vectors; CMOS; WCDMA; digital; driver; harmonic; linearity; long-term evolution (LTE); mixer; modulator; nonlinear; passive; predistortion; transmitter (TX);

fLanguage

English

Journal_Title

Microwave Theory and Techniques, IEEE Transactions on

Publisher

ieee

ISSN

0018-9480

Type

jour

DOI

10.1109/TMTT.2014.2309559

Filename

6762809