Charge Pump Voltage Regulator for PLL Jitter Reduction
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Solution Overview
Problem
Conventional charge pumps in phase locked loops face issues with incompatible charging and discharging currents, leading to voltage level instability and jitter generation when comparing signals are high impedance, affecting the stabilization of the phase locked loop.
Innovation Solution
A charge pump design incorporating a voltage regulator and constant current sources/sinks to dynamically adjust the bias voltage at the semiconductor devices' gates, ensuring balanced charging and discharging currents, and providing a bias voltage at the current output node for voltage compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional charge pump design is used, then the circuit structure is simple, but the voltage level at current output node becomes unstable causing jitter
Solution Approach 1:
A voltage regulator is introduced as an intermediary component between the charge pump output and the phase locked loop. The voltage regulator receives the current output from the charge pump and provides a regulated, stable voltage level to the phase locked loop, thereby eliminating jitter while maintaining the simplicity of the original charge pump structure.
Solution Approach 2:
The voltage regulator implements a feedback mechanism by monitoring the output voltage level and dynamically adjusting its output to maintain stability. This feedback control ensures that voltage fluctuations are corrected in real-time, preventing jitter without requiring complex circuit modifications.
2Stability of the object's composition
If conventional charge pump design is used, then the charging and discharging currents are unbalanced, but adding voltage regulation increases circuit complexity
Solution Approach 1:
The voltage regulator serves as a mediator that receives unbalanced charging and discharging currents from the charge pump and converts them into balanced, stable voltage levels. This allows the charge pump to operate with simple switching transistors while the voltage regulator handles the current balancing function externally.
Solution Approach 2:
The voltage regulator dynamically adjusts voltage parameters based on the incoming current levels. By changing the output voltage level in response to varying input conditions, the regulator compensates for imbalances between charging and discharging currents without modifying the charge pump transistor structure.
3Speed
If voltage level at current output node is increased to improve frequency response, then frequency of output signal increases, but voltage instability and jitter worsen
Solution Approach 1:
The voltage regulator employs feedback control to monitor and stabilize the output voltage level. Even when the charge pump increases current output to improve frequency response, the voltage regulator detects voltage fluctuations and adjusts its output accordingly to maintain stable voltage levels, preventing jitter while preserving fast frequency response.
Solution Approach 2:
The voltage regulator dynamically adapts its output characteristics based on real-time voltage conditions. When the charge pump operates at high current levels for fast frequency response, the regulator dynamically adjusts its regulation parameters to maintain voltage stability, allowing the system to achieve both high speed and high reliability.
Data Source
AI summary
A charge pump exhibiting a voltage compensation function is provided. The charge pump includes: a first current generator, a first semiconductor device, a second current generator, a second semiconductor device, and a voltage regulator. The voltage regulator dynamically adjusts a voltage level at the gate of the first or second semiconductor device so as to adjust a first current or a second current outputted to a current output node. In addition, the voltage regulator provides a bias voltage at the current output node when both the first and second semiconductor devices are turned off.