A 0.55 mW SAW-Less Receiver Front-End for Bluetooth Low Energy Applications

Abstract

This paper presents an ultra-low power direct conversion receiver front-end operating at 2.6 GHz with high out-of-band linearity and low quadrature error. This is achieved through the use of efficient mixers with improved out-of-band suppression, including rejection of the second harmonic, and an local-oscillator generator achieving current reuse and rejection of voltage-controlled oscillator signal imbalance through the use of complementary devices. Manufactured in 65 nm complementary metal-oxide-semiconductor and with a power consumption below 550 μW from a 0.85 V supply, the front-end achieves a conversion gain of 41 dB and a noise figure of 9.6 dB. It has an out-of-band IIP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> and IIP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> of -3 dBm and 29.5 dBm, respectively. The quadrature phase error is below 0.6°. Requiring only two inductors it occupies an area of just 0.15 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> excluding pads.