A 0.24-μV-Input-Ripple 8-μV-Input-Offset 10-MHz Chopper Operational Amplifier Employing MOS-DAC-Based Offset Calibration

This letter presents a chopper-stabilized multipath operational amplifier (OPA). By utilizing a 7-bit MOS-DAC-based offset calibration along with a passive ripple reduction filter, the OPA achieves a low input ripple in a power-efficient manner. The prototype IC is implemented in a 0.18-
$\mu \text{m}$
standard CMOS process and draws 0.85-mA current from a 5-V supply. The chopper OPA exhibits the minimal input ripple of
$0.24~\mu \text{V}$
(eight samples), which corresponds to an
$80\times $
reduction on the prior-art current-DAC-based offset calibration and a
$1.6\times $
reduction on the existing ripple reduction loops. In addition, this OPA exhibits excellent input-referred offset (
$8~\mu \text{V}$
), input-referred noise density (16 nV/
$\surd $
Hz), and power efficiency (GBW/ISUPPLY = 11.8).