Reference Current Generator Using Segmented Integration Capacitors
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Solution Overview
Problem
Current reference current generators require large compensation capacitors for stability, which is undesirable, especially in applications like frequency-to-digital converters and charge pump based clock multipliers, where a smaller capacitor size is needed.
Innovation Solution
A reference current generator design that uses a combination of amplifier bias current duty cycle throttling and double sampling with two integration capacitors operating on opposite phases, reducing the required compensation capacitance and increasing the update rate of the hold capacitor voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large compensation capacitor is used in the reference current generator, then stability is improved, but the capacitor size increases which is undesirable
Solution Approach 1:
The patent divides the single integration capacitor into two separate integration capacitors (first integration capacitor and second integration capacitor) that operate on opposite phases. This segmentation allows each capacitor to be smaller while collectively providing the stability function, thereby reducing the required compensation capacitance while maintaining system stability.
Solution Approach 2:
The patent implements periodic charging and discharging of the two integration capacitors on opposite phases. The first integration capacitor charges on one phase while the second charges on the opposite phase, creating a periodic action that maintains continuous integration function with smaller individual capacitor sizes, thus improving stability without requiring a large compensation capacitor.
2Speed
If the amplifier bandwidth is increased to improve response speed, then update rate is improved, but stability deteriorates requiring larger compensation capacitor
Solution Approach 1:
By implementing periodic charging and discharging of two integration capacitors on opposite phases, the system achieves high update rates without requiring high amplifier bandwidth. The periodic action of switching between the two capacitors provides continuous updates while the smaller individual capacitor sizes maintain stability, thus improving speed without sacrificing stability.
Solution Approach 2:
The patent segments the integration function across two capacitors operating on opposite phases, which allows the amplifier to operate at lower bandwidth while maintaining high update rate. Each capacitor handles a portion of the integration task periodically, reducing the bandwidth requirement while preserving stability.
Data Source
AI summary
Exemplary embodiments are related to current generators. A device may include a first integration path for charging a first integration capacitor during a first phase and a second integration path for charging a second integration capacitor during a second phase. The first integration capacitor may be configured for charging a capacitor coupled to an amplifier during the second phase and the second integration capacitor may be configured for charging the capacitor during the first phase.