Ultra low-power MEMS based radios for the IoT

Abstract

The start-up phase of the radios is responsible for the major energy drain in duty cycled Internet of Things (IoT) nodes. The main source of this energy drain is the long start-up of the loop based frequency synthesizer; especially the crystal oscillator (XO) frequency reference. In order to greatly reduce this energy drain, this paper presents radios based on micromachined Bulk Acoustic Wave (BAW) resonators that have the capability to start in few μs as opposed to ≈ 1 ms start-up of the traditional XO. In addition, these resonators also have a high Quality factor (Q). This results in the oscillators employing these resonators having excellent phase noise, thereby aiding the development of loop-free frequency synthesizers. The high-Q has also been leveraged to make a very good high frequency filter that has been employed in the sub-sampling receiver presented in this paper.