PLL Charge Pump PWM Calibration for Stable Loop Bandwidth

The patent implements a bandwidth calibration circuit that dynamically adjusts the charge pump current based on detected bandwidth conditions. The circuit monitors the PLL bandwidth and automatically calibrates the charge pump current to optimal levels, transforming the static charge pump design into a dynamic one that adapts to changing conditions. This resolves the contradiction by enabling low current (low power) operation when bandwidth is sufficient, while providing current increase only when needed for phase noise reduction.

The patent changes the operating parameters of the charge pump by introducing a calibration mechanism that adjusts the charge pump current as a variable parameter. The bandwidth calibration circuit modifies the current level based on detected performance metrics, allowing the system to optimize the trade-off between phase noise reduction and power consumption. This parameter change approach enables the system to operate at minimal necessary current levels rather than fixed high current.

The patent implements a feedback mechanism through the bandwidth calibration circuit that monitors PLL performance and adjusts the charge pump current accordingly. The circuit detects bandwidth conditions and feeds this information back to the charge pump control, creating a closed-loop system. This feedback approach prevents excessive current increase that would harm spur performance while ensuring sufficient current for phase noise reduction, thereby resolving the contradiction between these two performance metrics.

The patent transforms the static charge pump current design into a dynamic one by introducing calibration circuitry that adjusts current based on real-time bandwidth conditions. This dynamic adjustment allows the system to maintain optimal spur performance by avoiding unnecessary current increases, while still providing enhanced phase noise performance when conditions require it. The dynamic nature of the design prevents the degradation of spur performance associated with fixed high-current operation.

The patent implements a dynamic bandwidth calibration system that adjusts the loop bandwidth based on detected conditions. During acquisition, the circuit allows wider bandwidth for faster lock time. Once locked, the calibration circuit narrows the bandwidth to reduce phase noise. This dynamic bandwidth adjustment resolves the contradiction by providing wide bandwidth temporarily when needed for fast locking, then transitioning to narrow bandwidth for optimal phase noise performance.

The patent applies preliminary action by pre-calibrating the bandwidth and charge pump current before full operation begins. The calibration circuit prepares optimal parameters in advance based on initial conditions, allowing the PLL to achieve fast lock without subsequently requiring bandwidth widening that would harm phase noise. This preliminary optimization resolves the contradiction by establishing appropriate parameters before the lock process begins.

The patent implements a self-service mechanism where the bandwidth calibration circuit automatically detects and corrects bandwidth drift caused by supply voltage and temperature variations. The circuit monitors the PLL operation and self-adjusts the bandwidth parameters without external intervention. This self-calibrating approach resolves the contradiction by providing automatic bandwidth stabilization through relatively simple calibration logic, avoiding the need for complex manual compensation circuits while maintaining stability under varying conditions.

The patent introduces parameter changes by making the bandwidth characteristics variable rather than fixed. The calibration circuit adjusts bandwidth parameters in response to detected conditions, allowing the system to adapt to supply voltage and temperature variations. This parameter change capability provides bandwidth stabilization without requiring complex circuitry, as the adjustment is achieved through controlled modification of existing parameters rather than adding complex stabilization mechanisms.