This paper presents a novel on-chip digital method of calibration for a fully differential difference amplifier (FDDA), which is aimed at improved performance and reliability through enhanced robustness against variations of process parameters, voltage, temperature, and ageing drift. The proposed method was designed and verified within 130 nm CMOS technology design kit in Cadence environment. Calibration hardware is builtin with the calibrated FDDA circuit, and the whole integrated system is able to operate with only 0.4 V power supply. The effectiveness of the proposed calibration method was examined mainly by evaluation of the FDDA input offset voltage using Monte Carlo, and process corners and ageing analyses performed for the temperature range from -20°C to 85°C. The work established metrics for comparison of different calibration methods (i.e. digital calibration, chopper stabilization, analog calibration and autozero), which significantly differ in fundamentals of their operation. The proposed digital calibration outperforms its alternatives, while the precision of calibration, area and power consumption overhead are considered. The less advanced topology of digital calibration was previously implemented for variable-gain amplifier with considerable success (residual offset of the calibrated amplifier reaches fair levels of 13 µV to 167 µV). The concept proposed in this work utilizes advanced high precision calibration algorithm.
In this paper design and function of the fully differential (FD) switched-capacitor (SC) integrator for ultra-low voltage Sigma-Delta analog to digital converter (Σ-∆ ADC) are presented. The proposed integrator was designed for differential input signal and applicable as a main analog block of ultra-low voltage Σ-∆ ADC in standard 130 nm CMOS technology. The main block of proposed integrator is operational transconductance amplifier (OTA) based on two-stage Rail-to-Rail (RtR) FD operational amplifier (OPAMP) working in sub-threshold regime. The characteristic properties of this circuit is non-standard OTA topology, using SC common-mode feedback (CMFB) circuit and using switching T-gates. All of these subcircuits are supplied by only 0.6 V with achieved gain 24.09 dB and cutoff frequency 165.95 kHz.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.