A phase-domain readout circuit for a CMOS-compatible thermal-conductivity-based carbon dioxide sensor

A Portable Phase-Domain Magnetic Induction Tomography Transceiver with Phase-Band Auto-Tracking and Frequency-Sweep Capabilities

“…The main role of the PD-ΔƩM loop [ 13 ] is to make this DC component be zero by adjusting occurrences of ϕ 1 and ϕ 2 , and eventually the received input phase is detected as . While conventional PD-ΔƩMs [ 12 , 13 ] can resolve limited region of the input phase, that is, between ϕ 1 − and ϕ 2 − , the designed PD-ΔƩM intends to support 360-degree full coverage by utilizing a proposed phase-band auto-tracking scheme. The proposed auto-tracking scheme is facilitated by using the phase DAC where ϕ 1 and ϕ 2 are adaptively selected among eight-phase VCO outputs ϕ VCO <7:0> to fit, so that the input phase becomes located between ϕ 1 − and ϕ 2 − .…”

“…Therefore, in order to expedite the commercialization of portable MIT devices, this work presents a fully-integrated MIT transceiver circuit which features high-resolution accuracy, full coverage of phase input, phase-to-digital conversion and frequency sweep capabilities. A phase-locked loop (PLL) with a multi-phase voltage-controlled oscillator (VCO) [ 11 ] is included for a frequency-sweep magnetic-coil transmission, and a phase-domain sigma-delta modulator (PD-ΔΣM) [ 12 ] with phase-band auto-tracking and scalable conversion rate is proposed for the high-resolution detection of magnetic phase shifts through target objects. This proposed MIT transceiver is fabricated and experimentally verified to achieve the measured SNDR of 101.7 dB.…”

A Phase-Domain Readout Circuit for a CMOS-Compatible Hot-Wire CO2Sensor

“…In contrast with earlier TC sensors based on transient measurements [16], [24], we present a readout circuit that allows the heating and temperature-sensing functions to be combined in a single resistive transducer [26]. This greatly simplifies fabrication, since only a single extra etch step is required to realize a tungsten hot-wire transducer in the via layer of a standard CMOS process [14].…”