A Harmonic-Rejection Radio Frequency Transmitter Employing 33%-Duty-Cycle LO Waveforms

This paper reports a SAW-less RF transmitter that proposes a third harmonic suppression technique by employing 33<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">%</sup>-duty-cycle local oscillator (LO) waveforms. Besides, it employs a N-path switched-capacitor (SC) mixer, providing a high Q bandpass filtering at different RF to achieve a good compromise between output power and linearity. The gain provided by a transconductor (gm) could not only compensate for attenuation caused by 3fLo-suppression but also enhance out-of-band (OB) noise rejection effectively. An auxiliary gm is introduced to improve the linearity of the power amplifier (PA) driver. Simulated in 65nm CMOS process, our transmitter manifests good linearity (CIM3 <-52dBc) under 2.2dBm output power. The OB noise is <-155.5dBc/Hz. The transmitter consumes 118mW power. The active area is 0.075 mnm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>.