A ±0.15% RH Inaccuracy Humidity Sensing System With ±0.44 °C (3σ) Inaccuracy On-Chip Temperature Sensor

This article describes a high accurate humidity sensing system. The humidity sensor and the interface circuit of our system-in-package (SiP) are 3-D stacked to optimize integration density with small foot print. A single reconfigurable ADC is utilized for both 3-D stacked humidity and on-chip temperature sensors. An incremental
$\Delta \Sigma $
ADC with a reconfigurable
$\Delta \Sigma $
modulator is employed with dual input stages. With the combination of chopping, correlated double sampling (CDS), dynamic element matching (DEM), and system-level chopping techniques, high accuracy sensing system is achieved. The interface circuit, implemented in a standard CMOS
$0.18~\mu \text{m}$
CMOS technology, occupies an area of 1.24 mm
$^{\mathbf {2}}$
. The SiP sensing system dissipates only
$146.5~\mu \text{A}$
and
$25~\mu $
A from 3.3 V supply and 1.8 V supply, respectively. Its humidity inaccuracy is 0.15 %RH with a resolution of 0.012 %RH, while a temperature inaccuracy is 0.44 °C (
$3\sigma $
) with a resolution of 0.015 °C.