Adaptive PLL Loop Filter Tuning for Stability and Area Control
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Solution Overview
Problem
Existing phase-locked loop circuits face instability and increased area requirements due to changes in Kvco and power supply voltage, leading to difficulties in maintaining frequency accuracy and loop parameter stability.
Innovation Solution
A phase-locked loop system with a circuit parameter regulator that adjusts filtering resistors, capacitors, frequency division coefficients, and signal frequencies to maintain loop parameters within a preset margin range, minimizing circuit area while ensuring stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If capacitance values of filtering capacitors are increased exponentially to maintain stable loop parameters when circuit parameters change significantly, then loop parameter stability is improved, but the capacitor area increases, resulting in an increase in the area occupied by the phase-locked loop circuit
Solution Approach 1:
The patent implements dynamic adjustment of loop filter parameters (capacitance and resistance values) based on real-time detection of phase-locked loop operating states. The circuit parameter regulator dynamically modifies the capacitance value of the filtering capacitor and resistance value of the filtering resistor according to detected frequency offsets and locking states, replacing the static exponential increase approach with adaptive dynamic control that maintains stability while minimizing area.
Solution Approach 2:
The patent changes the parameters of the loop filter (capacitance and resistance values) dynamically based on the operating conditions of the phase-locked loop. The circuit parameter regulator adjusts these parameters according to the detected locking state and frequency offset, allowing the system to maintain stability with much smaller capacitor values than would be required with fixed parameters.
2Measurement precision
If the circuit parameter adjustment manner in the prior art is used to make the change in Kvco smaller, then frequency accuracy is improved, but the range of the output frequency of the voltage-controlled oscillator is reduced, lowering the margin and making it difficult to meet pre-configured frequency accuracy requirements
Solution Approach 1:
The patent dynamically adjusts the loop filter parameters (capacitance and resistance) based on the detected phase-locked loop state and frequency offset. This dynamic adjustment allows the system to maintain high frequency accuracy when needed while preserving a wide output frequency range, as the parameters are optimized in real-time rather than fixed to compromise one aspect for the other.
Solution Approach 2:
The patent implements a feedback mechanism where the circuit parameter regulator continuously detects the operating state of the phase-locked loop (including frequency offset and locking status) and uses this information to adjust the loop filter parameters. This closed-loop feedback control enables the system to maintain frequency accuracy while adapting to different operating conditions and preserving frequency range.
3Use of energy by moving object
If the phase-locked loop operates with reduced power supply voltage, then power consumption is reduced, but the control voltage of the voltage-controlled oscillator decreases, requiring Kvco to increase which destabilizes the loop
Solution Approach 1:
The patent dynamically adjusts the loop filter parameters (capacitance and resistance values) in response to changes in power supply voltage and operating conditions. When power supply voltage decreases, the circuit parameter regulator modifies these parameters to compensate for the reduced control voltage and prevent Kvco instability, enabling the system to operate reliably at lower power consumption levels.
Solution Approach 2:
The patent changes the loop filter parameters (capacitance and resistance) based on the detected power supply voltage level and operating state. This parameter adaptation allows the phase-locked loop to maintain stability across a wide range of power supply voltages, enabling low-power operation without sacrificing reliability.
Data Source
AI summary
A phase-locked loop working system includes: a pre-frequency divider, a phase frequency detector, a charge pump, a filter, a voltage-controlled oscillator, a loop frequency divider and a circuit parameter regulator. The phase frequency detector, the charge pump, the filter, the voltage-controlled oscillator and the loop frequency divider are sequentially coupled end to end to form a phase-locked loop circuit. The circuit parameter regulator is coupled to the phase-locked loop circuit and is used to adjust a filtering resistor and a filter capacitor in the filter, to control loop parameters generated by the phase-locked loop circuit to be within a preset margin range. The circuit parameter regulator is coupled to the phase-locked loop circuit and is further used to adjust a frequency-division coefficient of the pre-frequency divider and/or a frequency of the signal to be processed inputted into the pre-frequency divider.