Charge Pump Circuit With Offset Current for Low-Noise PLL Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing charge pump circuits in PLL systems face limitations in power consumption flexibility due to the requirement for voltage followers, which restrict the current flow and lead to increased noise and power consumption, especially when switching between current supply and draw.
Innovation Solution
A charge pump circuit design that includes a push-type differential amplifier circuit with a third current source providing a negative offset current, allowing for balanced current supply and draw, reducing power consumption and noise by eliminating unnecessary current states and enhancing phase setting accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage follower circuit is used to reduce current error during switching between current draw and supply, then current switching accuracy is improved, but power consumption increases and design flexibility decreases
Solution Approach 1:
The patent extracts and removes the voltage follower circuit from the charge pump configuration. By eliminating this circuit component, the patent achieves reduced power consumption while maintaining current switching accuracy through an alternative operational amplifier configuration that does not require continuous current flow.
Solution Approach 2:
The patent changes the operational parameters by allowing the operational amplifier to operate without the constraint of flowing the same current as the current sources. This parameter change enables flexible power consumption design while maintaining the ability to accurately switch between current draw and supply states.
2Measurement precision
If a voltage follower circuit is used to reduce current error during switching, then current switching accuracy is improved, but design flexibility decreases
Solution Approach 1:
The patent removes the voltage follower circuit that constrained design flexibility. This extraction allows the operational amplifier to operate in a more versatile manner, enabling designers to optimize power consumption according to specific application requirements while maintaining current switching accuracy.
Solution Approach 2:
The patent introduces dynamic operation by allowing the operational amplifier to function without fixed current constraints. This dynamic approach enables the circuit to adapt to different power consumption requirements and design scenarios, enhancing overall design flexibility while preserving switching accuracy.
3Reliability
If high current states are maintained to ensure adequate signal levels, then signal quality is improved, but power consumption and noise increase
Solution Approach 1:
The patent implements periodic action by using the operational amplifier to periodically adjust and balance the current between the first and second nodes only when necessary. This periodic intervention maintains adequate signal levels and quality while minimizing the time that high current states are active, thereby reducing associated noise and power consumption.
Solution Approach 2:
The patent employs feedback mechanisms through the operational amplifier that continuously monitors and balances the current distribution. This feedback control ensures signal quality is maintained by correcting imbalances only when needed, rather than maintaining continuously high current states, thus reducing noise and power consumption.
Data Source
AI summary
There is configured a charge pump circuit for outputting a phase difference current to a first node, the charge pump circuit including a first current source coupled between a high potential power supply node and the first node, a second current source coupled between a low potential power supply node and the first node, a first switch coupled between the first current source and the first node, a second switch coupled between the second current source and the first node, a third switch coupled between the first current source and a second node, a fourth switch coupled between the second current source and the second node, a third current source for supplying a negative offset current to the first node, and a push-type differential amplifier circuit an input side of which is coupled to the first node, and an output side of which is coupled to the second node.