A 0.9-V 28-MHz Highly Digital CMOS Dual-RC Frequency Reference With ±200 ppm Inaccuracy From -40 °C to 85 °C

This article presents an energy-efficient dual- RC frequency reference intended for wireless sensor nodes. It consists of a digital frequency-locked loop (FLL) in which the frequency of a digitally controlled oscillator (DCO) is locked to a temperature-independent phase shift derived from two different RC poly-phase filters (PPFs). Phase...

A Self-Calibrated Hybrid Thermal-Diffusivity/Resistor-Based Temperature Sensor

This article describes a hybrid temperature sensor in which an accurate, but energy-inefficient, thermal diffusivity (TD) sensor is used to calibrate an inaccurate, but efficient, resistor-based sensor. The latter is based on silicided polysilicon resistors embedded in a Wien-bridge (WB) filter, while the former is based on an electrothermal...

Compact Thermal Diffusivity Sensors for On-Chip Thermal Management

Today’s systems-on-chip (SOCs) and microprocessors are complex systems that require multiple temperature sensors to monitor temperature variations in multiple spots on a single silicon die. For such thermal management applications, specialized compact and fast temperature sensors are required. This is necessary because executing an intensive...

A 6800-μ m² Resistor-Based Temperature Sensor with ±0.35 °c (3σ) Inaccuracy in 180-nm CMOS

This paper describes a compact resistor-based temperature sensor that has been realized in a 180-nm CMOS process. It occupies only 6800 μ m², thanks to the use of a highly digital voltage-controlled oscillator (VCO)-based phase-domain sigma-delta modulator, whose loop filter consists of a compact digital counter. Despite its small...

IQ offset and gain mismatch compensation for phase-domain ADC

A phase-domain analog-to-digital converter (PhADC) is a promising alternative to a pair of amplitude-domain in-phase and quadrature (IQ) ADCs for low power FSK/PSK demodulation, but due to the nonlinear amplitude-to-phase conversion, IQ offsets and gain mismatch can produce nonlinear phase distortions which that can lead to phase errors and an...

A Resistor-Based Temperature Sensor With a 0.13 pJ·K² Resolution FoM

This paper describes a high-resolution energy-efficient CMOS temperature sensor, intended for the temperature compensation of MEMS/quartz frequency references. The sensor is based on silicided poly-silicon thermistors, which are embedded in a Wien-bridge RC filter. When driven at a fixed frequency, the filter exhibits a temperature-dependent...

A Phase-Domain Readout Circuit for a CMOS-Compatible Hot-Wire CO₂ Sensor

This paper presents a readout circuit for a carbon dioxide (COࠢ) sensor that measures the CO₂-dependent thermal time constant of a hot-wire transducer. The readout circuit periodically heats up the transducer and uses a phase-domain Δ Σ modulator to digitize the phase shift of the resulting...

A Three-Phase Unbalanced Load Flow Solver for Large-Scale Distribution Power Systems

The calculation of power flow through electrical networks has been utilized commonly in transmission networks as the first calculation tool to assess their steady state conditions. However, the current introduction of renewable micro-sources (many of them single-phase connected) and the implementation of microgrids makes the calculation of power...

A Charge-Redistribution Phase-Domain ADC Using an IQ-Assisted Binary-Search Algorithm

Phase-domain Analog-to-Digital Converters (Ph-ADCs) have been considered for power-efficient implementation of body-area network transceivers employing phase demodulation. Conventional implementations of the Ph-ADCs, which work based on a full-flash zero-crossing algorithm, use linear resistive/current combiners to determine the thermometer...

A Highly-Scalable Thermal-Diffusivity-Based Temperature Sensor

A highly digital temperature sensor, based on the thermal diffusivity of silicon, for thermal management applications has been reported. Recently, Thermal-Diffusivity based temperature sensors have undergone a radical change from an analog-based readout architecture to a more digital VCO-based one. However the more digital approach led to...

Integrated Temperature Sensors based on Heat Diffusion

This thesis describes the theory, design and implementation of a new class of integrated temperature sensors, based on heat diffusion. In such sensors, temperature is sensed by measuring the time it takes for heat to diffuse through silicon. An on-chip thermal delay can be determined by geometry and the thermal diffusivity of silicon, and since...

An Energy-Efficient, Resistor-Based, Smart Temperature Sensor

A Temperature-to-Digital Converter Based on an Optimized Electrothermal Filter

This paper describes the design of a CMOS temperature-to-digital converter (TDC). It operates by measuring the temperature-dependent phase shift of an electrothermal filter (ETF). Compared to previous work, this TDC employs an ETF whose layout has been optimized to minimize the thermal phase spread caused by lithographic inaccuracy. To minimize...