Positive-Feedback-Based Design Technique for Inherently Stable Active Load Toward High-Gain Amplifiers With Unipolar a-IGZO TFT Devices
Mohit Dandekar, Kris Myny, Wim Dehaene
Abstract
This letter presents analysis of an inherently stable positive-feedback-based active load, first reported in our prior work, to realize high gain analog amplifiers using unipolar a-IGZO TFT technology. Additionally reported are theoretical performance bounds and design guidelines to maximally utilize a general positive-feedback scheme for the active load while maintaining stability. To demonstrate a design implementation, a single stage fully differential operational transconductance amplifier with common mode feedback has been manufactured and measured to have 40-dB open-loop gain at dc and a unity gain frequency of 61 kHz while driving a 30-pF load capacitance.
Topics & Concepts
Open-loop gainTransconductanceAmplifierOperational transconductance amplifierOperational amplifierLoop gainFully differential amplifierCapacitancePositive feedbackNegative feedback amplifierElectronic engineeringControl theory (sociology)Computer sciencePhase marginHigh-gain antennaStability (learning theory)Frequency compensationNegative feedbackVoltageEngineeringTransistorElectrical engineeringPhysicsCMOSControl (management)Quantum mechanicsElectrodeMachine learningArtificial intelligenceThin-Film Transistor TechnologiesAnalog and Mixed-Signal Circuit DesignCCD and CMOS Imaging Sensors