DCO Current Calibration Using Capacitor Bank Thresholds
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Solution Overview
Problem
Conventional digitally controlled oscillators (DCOs) in digital phase-locked loops (DPLLs) consume high power due to fixed maximum current settings, which is not suitable for low power design requirements, especially in wireless communication devices like Bluetooth and Wi-Fi.
Innovation Solution
A method and processing circuit that dynamically tunes the current source of a DCO based on a tunable capacitor bank, determining a specific threshold and gradually reducing the current level while ensuring the DPLL can still track channel frequencies, thereby minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current provided to the DCO is configured as a maximum or large current to ensure oscillation startup and operation over different channel frequencies, then the reliability of oscillation startup and frequency operation is improved, but the power consumption increases
Solution Approach 1:
The patent applies dynamics by making the current level provided to the DCO adjustable rather than fixed. The current calibration mechanism dynamically determines the minimum current level required for the DCO to start oscillation and operate across channel frequencies, allowing the system to transition from a static maximum current configuration to a dynamic optimized current level that reduces power consumption while maintaining reliability.
Solution Approach 2:
The patent changes the current parameter from a fixed maximum value to a calibrated minimum value. By introducing a current calibration mechanism that determines the specific current level required for reliable operation, the system optimizes the current parameter to the minimum necessary level, thereby reducing power consumption while ensuring oscillation startup and frequency operation reliability.
2Adaptability or versatility
If the current provided to the DCO is configured as a maximum or large current to ensure operation under different channel frequencies, then the adaptability to different channel frequencies is improved, but the power consumption increases
Solution Approach 1:
The patent makes the current level adaptive by introducing a calibration mechanism that determines the minimum current required for the DCO to operate across different channel frequencies. This dynamic current calibration allows the system to maintain adaptability to different channel frequencies while operating at optimized current levels rather than fixed maximum levels, thereby reducing power consumption.
Solution Approach 2:
The current calibration mechanism enables the system to self-determine the minimum current level required for reliable operation across channel frequencies. By automatically calibrating the current level without external intervention, the system optimizes power consumption while maintaining the adaptability to operate under different channel frequency conditions.
3Use of energy by moving object
If the current provided to the DCO is reduced to lower power consumption, then the power consumption is improved, but the reliability of oscillation startup and frequency operation deteriorates
Solution Approach 1:
The patent applies preliminary action by performing current calibration before normal operation to determine the minimum current level required for reliable DCO operation. This preliminary calibration step ensures that when the system operates at the calibrated current level, the reliability of oscillation startup and frequency operation is maintained, avoiding the need to operate at higher maximum current levels that would increase power consumption.
Solution Approach 2:
The current calibration mechanism uses feedback by monitoring the DCO operation at different current levels to determine the minimum current required for reliable operation. This feedback-based calibration ensures that the system operates at the lowest current level that still maintains oscillation startup reliability and frequency operation, thereby optimizing power consumption without sacrificing reliability.
Data Source
AI summary
A method for tuning a current source of a digitally controlled oscillator having an LC tank having a tunable capacitor bank includes: determining a specific threshold according to a resolution of a bit number of the tunable capacitor bank; configuring a current flowing through the current source at a first current level; tuning the current flowing through the current source from the first current level to a lower current level; comparing a variation of a digital value of the tunable capacitor bank with the specific threshold, the digital value corresponding to the lower current level; and determining that a current level required by the digitally controlled oscillator is decreased down to the lower current level and then configuring the current flowing through the current source at the lower current level if the variation of the digital value is smaller than the specific threshold.