6. mm-Wave Monolithic Integrated Sensor Nodes

This chapter presents the analysis, implementation, and measurement of two fully integrated mm-wave temperature sensor nodes with on-chip antennas. These two sensor nodes provide two solutions for integrating a sensor node with on-chip antenna(s). The first solution contains two on-chip antennas, one for Tx and one for Rx, in which Tx/Rx have separate antennas. The second solution is a one on-chip antenna solution, in which the on-chip antenna is reused by Tx/Rx through an RF switch. These sensor nodes are implemented in 65 nm CMOS technology. The first sensor node contains a monopole antenna at 71 GHz for RF power harvesting, a storage capacitor array, an End-of-Burst monitor, a temperature sensor, and an ultra-low-power transmitter at 79 GHz. At 71 GHz, the RF to DC converter achieves a power conversion efficiency of 8% for 5 dBm input power. The second sensor node contains an integrated antenna, an RF switch, an on-chip wireless power receiver, and a temperature-correlated ultra-low-power transmitter. It measures only 1.83 mm² in 65 nm CMOS and weighs 1.6 mg. With the on-chip 30/65 GHz dual-frequency antenna and a three-stage inductor-peaked rectifier, the node can be wirelessly charged to 1.2 V. The output frequency of the temperature-correlated transmitter varies from 78.92 to 78.98 GHz, with a slope of 1.4 MHz/^∘C.