9.4 A 0.5V 1.15mW 0.2mm<sup>2</sup> Sub-GHz ZigBee receiver supporting 433/860/915/960MHz ISM bands with zero external components
The rapid proliferation of Internet of Things has urged the development of ultra-low-power (ULP) radios at the lowest possible cost, while being universal for worldwide markets. Both current-reuse [1,2] and ultra-low-voltage [3] receivers are promising solutions. [1] unifies most RF-to-BB functions in one cell for current-mode signal processing, resulting in a high IIP3 (-6dBm) at small power (2.7mW) and area (0.3mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ). However, outside the current-reuse cell, another supply is required for other circuits, complicating the power management [1,2]. [3] facilitates single-0.3V operation of the entire receiver at 1.6mW for energy harvesting, but the limited voltage headroom and transistor f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> call for bulky inductors/transformers to assist the biasing and to tune out the parasitics, penalizing the IIP3 (-21.5dBm) and area (2.5mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ). In both cases, a fixed LC network was adopted for input matching and pre-gain to lower the NF, which is costly and inflexible for multi-band designs.