Dynamic Amplifier Biasing via Driving Capacitors in Pipeline ADCs
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Solution Overview
Problem
Pipeline analog-to-digital converters (ADCs) face challenges in reducing power consumption while maintaining sampling rate and precision, particularly due to inefficient power usage in amplifier stages during reset and charge transfer phases, and limited slew rate which affects settling time.
Innovation Solution
The implementation of a current mirror with a sink transistor and a driving capacitor to dynamically regulate the gate voltage of the sink transistor, allowing for temporary increases in drain current during charge transfer phases and rapid power switching, thereby improving response time and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the amplifier operates continuously to maintain fast response time, then the sampling rate and precision are maintained, but the power consumption increases significantly
Solution Approach 1:
The amplifier is dynamically switched between active and inactive states based on operational phase. During charge transfer phases, the amplifier is activated to ensure fast response and precision. During reset phases, the amplifier is deactivated to reduce power consumption. This dynamic operation resolves the contradiction by adapting the amplifier's state to the immediate operational requirements rather than maintaining continuous operation.
Solution Approach 2:
The system employs periodic activation of the amplifier synchronized with the charge transfer phases. The amplifier is turned on during charge transfer phases when fast response is needed, and turned off during reset phases when power consumption is the priority. This periodic action pattern allows the system to maintain performance requirements while significantly reducing overall power consumption.
2Use of energy by moving object
If the amplifier is turned off during reset phases to reduce power consumption, then power usage is optimized, but the response time increases when reactivation is needed
Solution Approach 1:
The capacitor is pre-charged during reset phases while the amplifier is inactive. When the amplifier needs to be reactivated during charge transfer phases, the pre-charged capacitor provides immediate current boost, eliminating the delay that would otherwise occur during amplifier startup. This preliminary charging action ensures that the amplifier can transition from inactive to active state without response time penalty.
Solution Approach 2:
The capacitor acts as an intermediary energy storage element between the power supply and the amplifier. It accumulates energy during reset phases and releases it rapidly when the amplifier needs to activate, bridging the gap between power savings and fast response requirements. This intermediary mechanism allows the amplifier to be turned off completely while still enabling rapid reactivation when needed.
3Speed
If the gate voltage of the sink transistor is increased to improve slew rate, then the response time is reduced, but the power consumption increases
Solution Approach 1:
The gate voltage of the sink transistor is periodically increased only during charge transfer phases when high slew rate is required for fast response. During reset phases, the gate voltage returns to normal levels, reducing power consumption. This periodic voltage boosting resolves the contradiction by applying high power only when performance is critical rather than maintaining elevated voltage continuously.
Solution Approach 2:
The gate voltage is dynamically adjusted based on operational phase requirements. The circuit transitions from normal operating voltage during reset phases to boosted voltage during charge transfer phases. This dynamic voltage adjustment allows the system to achieve high slew rate when needed while minimizing power consumption during non-critical phases, effectively resolving the speed-power tradeoff.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the slew rate and response time of the amplifier output without increasing overall power consumption, optimizing power usage by turning off the amplifier during reset phases and rapidly recharging the capacitors for efficient operation.
Implementation Method 1
A driving capacitor is used to temporarily increase the gate voltage of the sink transistor, which causes a temporary increase in the drain current of the sink transistor
Implementation Method 2
A current mirror contains a sink transistor that receives a drain current from an electronic device
Data Source
AI summary
A system and a method are disclosed for using driving capacitors to dynamically bias an amplifier in a stage of a pipeline analog-to-digital converter (ADC). The drain of the amplifier is connected to a sink transistor, and the driving capacitors are used to raise or lower the voltage at the gate of the sink transistor. The driving capacitors can be used in this manner to rapidly power the amplifier on and off to save power and/or to selectively boost the drain current of the amplifier to improve the response time of the pipeline ADC stage.