Bias Current Generator Fast Startup Dynamics
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Solution Overview
Problem
Conventional bias current generators face inefficiencies due to constant operation during inactive periods and slow startup times when transitioning from sleep mode to active operation, leading to prolonged power consumption and delayed stable bias current generation.
Innovation Solution
A bias current generator with a current source that biases operational amplifier nodes only during dormant mode with a small node-biasing current, allowing rapid transition to active mode with minimal power consumption by preventing node biasing during active operation, utilizing a switching network to manage the node-biasing current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the bias current generator is left running during sleep mode to enable fast wake-up, then the transition speed from sleep mode to normal operation is improved, but power consumption increases due to continuous bias current drain
Solution Approach 1:
The patent applies dynamics by making the bias current generator switchable between active and dormant modes. The enable signal dynamically controls the switching transistor to connect or disconnect the bias current generator from the operational amplifier, allowing the system to adapt its operation state based on whether fast wake-up or power saving is needed.
Solution Approach 2:
The patent applies preliminary action by pre-charging the operational amplifier nodes with a small bias current during sleep mode through the dormant mode operation. This preliminary biasing prepares the nodes for rapid transition to active mode without requiring full bias current, enabling fast wake-up while minimizing power consumption during idle periods.
2Use of energy by moving object
If the bias current generator is switched off during sleep mode to reduce power consumption, then power consumption is improved, but the transition time from sleep mode to normal operation increases due to feedback settling time
Solution Approach 1:
The patent applies preliminary action by maintaining a small dormant bias current that continuously pre-biases the operational amplifier nodes during sleep mode. This preliminary action ensures the nodes are already at appropriate voltage levels before wake-up, eliminating the need for lengthy feedback settling and enabling rapid transition to active mode.
Solution Approach 2:
The patent applies partial action by using a dormant bias current that is significantly smaller than the full active bias current (e.g., 100 nA vs. 10 μA). This partial biasing is sufficient to maintain node voltages during sleep mode for fast wake-up, but inadequate to cause significant power consumption, thus achieving the optimal balance between speed and power.
3Stability of the object's composition
If a conventional bias current generator operates continuously to maintain stable bias current, then the stability of bias current generation is improved, but the efficiency deteriorates due to constant current drain during inactive periods
Solution Approach 1:
The patent applies dynamics by implementing a switchable bias current generator that can operate in two distinct states: active mode with full bias current for stability during normal operation, and dormant mode with minimal bias current for efficiency during sleep mode. The enable signal dynamically transitions between these states.
Solution Approach 2:
The patent applies periodic action by alternating between active and dormant modes based on the processor's operational state. During normal operation, the generator operates actively to provide stable bias current. During sleep mode, it switches to dormant mode with minimal current consumption, creating a periodic pattern that optimizes both stability and efficiency over time.
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
Enables rapid transition from dormant to active operation in nanoseconds with significantly reduced power consumption during inactive periods, maintaining stable bias current generation with a small node-biasing current compared to the bias current.
Implementation Method 1
A current source biases nodes of an operational amplifier in the bias current generator with a node-biasing current conducted through a switching network
Implementation Method 2
The switching network functions so that the operational amplifier nodes are biased by the node-biasing current only while the bias current generator is turned off during a dormant mode of operation
Implementation Method 3
Feedback through operational amp 105 will thus keep the source voltage for transistor M1 equal to the reference voltage VGB such that a bias current I conducted through resistor R1 equals VBG/R1 by Ohm's law
Implementation Method 4
This bias current I is then mirrored through current mirrors formed by a diode-connected PMOS transistor P1 having its gate (and drain) voltage also driving the gates of PMOS transistors P2 and P3
Data Source
AI summary
A bias current generator is disclosed that include an operational amplifier that is self-biased during an inactive period with a bias current to bias a gate of an output transistor. Since the inactive period bias is close to an active period bias applied to the gate of the output transistor during active operation of the bias current generator, the speed of transition from the inactive period to the active period is enhanced by the self-biasing of the operational amplifier.