A Multiband LTE SAW-Less CMOS Transmitter with Source-Follower-Driven Passive Mixers, Envelope-Tracked RF-PGAs, and Marchand Baluns

Tomohiro SANO
Yoshikazu FURUTA
Mitsuhiko HOKAZONO
Tetsuya HEIMA
Hisayasu SATO

IEICE TRANSACTIONS on Electronics   Vol.E96-C    No.6    pp.774-782
Publication Date: 2013/06/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E96.C.774
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuits and Related SoC Integration Technologies)
multiband,  LTE,  SAW-less,  CMOS,  transmitter,  quadrature modulator,  source follower,  envelope-tracking,  programmable gain amplifier,  balun,  

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We present a multiband LTE SAW-less CMOS transmitter with source-follower-driven passive mixers, envelope-tracked RF-programmable gain amplifiers (RF-PGAs), and Marchand Baluns. A driver stage for passive mixers is realized by a source follower, which enables a quadrature modulator (QMOD) to achieve low noise performance at a 1.2 V supply and contributes to a small-area and low-power transmitter. An envelope-tracking technique is adopted to improve the linearity of RF-PGAs and obtain a better Evolved Universal Terrestrial Radio Access Adjacent Channel Leakage power Ratio (E-UTRA ACLR). The Marchand balun covers more frequency bands than a transformer and is more suitable for multiband operation. The proposed transmitter, which also includes digital-to-analog converters and a phase-locked loop, is implemented in a 65-nm CMOS process. The implemented transmitter achieves E-UTRA ACLR of less than -42 dBc and RX-band noise of less than -158 dBc/Hz in the frequency range of 700 MHz–2.6 GHz. These performances are good enough for multiband LTE and SAW-less operation.