Reference Generator Low Output Impedance Transient Handling
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Solution Overview
Problem
Reference generators in electronic systems face challenges in maintaining stable reference signals under varying operational conditions such as rapidly changing load impedances and transient current demands, which affects the accuracy of systems like pipelined analog-to-digital converters.
Innovation Solution
The development of differential amplifier structures that provide low output impedances with low supply currents, both sink and source currents, and are insensitive to supply voltage variations, utilizing transistors and cascode stages to enhance stability and power supply rejection ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional reference generators are used, then the system can operate with simple structure, but the reference signal stability degrades under varying load impedances and transient current demands
Solution Approach 1:
The reference generator is divided into multiple operational modes or stages, allowing different circuit configurations to be used under different operating conditions. This segmentation enables the generator to maintain signal stability under varying loads while keeping the overall structure manageable through modular design.
Solution Approach 2:
The reference generator employs dynamic circuit elements such as switches and controllable current sources that can adapt their behavior based on operating conditions. This dynamic operation allows the generator to maintain low output impedance and stable reference signals during transient current demands and varying load impedances.
2Productivity
If the reference generator provides high current capability to handle transient demands, then the transient response improves, but the supply current consumption increases
Solution Approach 1:
The reference generator uses periodic switching of current sources to provide high transient current capability only when needed, rather than maintaining high current capability continuously. This periodic activation of current sources allows the generator to handle transient demands effectively while consuming less average supply current.
Solution Approach 2:
The generator dynamically changes its operating parameters, particularly the current source activation state, based on the instantaneous load conditions. During transient current demands, the generator activates additional current sources to provide high current capability, and during steady-state operation, it reduces current source activity to minimize supply current consumption.
3Use of energy by moving object
If the generator operates with low supply voltage to improve power efficiency, then energy consumption decreases, but the sensitivity to supply voltage variations increases
Solution Approach 1:
The reference generator incorporates feedback mechanisms that monitor the reference signal stability and adjust the current source operation accordingly. This feedback control allows the generator to maintain low sensitivity to supply voltage variations even when operating with low supply voltage, by dynamically compensating for voltage fluctuations through controlled current adjustment.
Data Source
AI summary
Reference generator embodiments are provided with low output impedances to enhance reference stability in the presence of varying loads. The generators are structured to provide these impedances in an efficient manner (i.e., with low supply currents) and also to provide both sink and source currents to better handle large transient current demands. The generators also include cascode structures that facilitate operation with low values of a supply voltage and that provide a low sensitivity to variations in this supply voltage. The embodiments are especially suited for use in signal converter systems.