Pierce Oscillator Bias Control for Low-Jitter Amplitude Regulation
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Solution Overview
Problem
Existing analogue amplitude regulators for Pierce oscillators consume high power and introduce noise, leading to clock jitter, and lack flexibility in controlling bias current.
Innovation Solution
A digital amplitude regulation method using peak detectors to monitor oscillation amplitude and adjust bias current digitally, entering a sleep state to conserve power and intermittently updating the bias current to maintain oscillation within thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an analogue amplitude regulator is used to control the bias current of the Pierce oscillator, then the oscillation amplitude can be maintained within acceptable ranges, but the power consumption increases significantly and noise is introduced causing clock jitter
Solution Approach 1:
The patent replaces the mechanical/electronic analogue amplitude regulator with a digital control system. The digital system uses a peak detector to monitor oscillation amplitude and a digital-to-analogue converter (DAC) to adjust the bias current based on digital control signals. This substitution eliminates the continuous operation of analogue regulators, allowing the system to enter low-power states while maintaining amplitude control through periodic digital measurements and adjustments.
2Reliability
If an analogue amplitude regulator is used to control the bias current, then the oscillation amplitude can be maintained, but undesirable noise is introduced into the circuit causing clock jitter
Solution Approach 1:
The patent replaces the noise-prone analogue regulator circuitry with a digital control architecture. The digital system processes amplitude measurements and generates control signals without introducing the continuous analogue noise that causes clock jitter. The digital-to-analogue converter provides clean analogue control signals only when needed, rather than continuous analogue regulation.
Solution Approach 2:
The digital amplitude control system operates periodically rather than continuously. The peak detector measures oscillation amplitude at specific intervals, and the DAC updates the bias current only when amplitude thresholds are exceeded. This periodic operation reduces noise introduction compared to continuous analogue regulation, allowing the system to enter quiet low-power states between measurements.
3Reliability
If the bias current is increased to maintain oscillation amplitude under environmental changes, then the oscillation stability improves, but the power consumption increases
Solution Approach 1:
The patent implements dynamic bias current adjustment where the system adapts the bias current level based on actual oscillation amplitude measurements. Rather than maintaining a high bias current continuously to ensure stability under all conditions, the system dynamically adjusts the current only when amplitude deviations are detected, optimizing the balance between stability and power consumption.
Solution Approach 2:
The system employs feedback control where the peak detector continuously monitors oscillation amplitude and feeds this information back to the digital control logic. When the amplitude falls outside acceptable ranges, the feedback triggers an adjustment of the bias current via the DAC. This closed-loop feedback ensures oscillation stability is maintained only when necessary, rather than requiring continuously high power consumption.
4Reliability
If continuous monitoring of oscillation amplitude is performed to maintain stability, then the oscillation remains within thresholds, but the power consumption increases
Solution Approach 1:
The patent implements periodic amplitude monitoring rather than continuous monitoring. The peak detector is activated at intervals to measure oscillation amplitude, and the digital control system updates the bias current only when measurements indicate threshold violations. This periodic approach maintains amplitude control while allowing the system to enter low-power states between measurements, significantly reducing overall power consumption.
Solution Approach 2:
The system uses the existing oscillation signal itself to perform the amplitude measurement through the peak detector, rather than requiring separate continuous monitoring circuits. The digital control logic services the amplitude control function by processing periodic measurements and triggering bias current adjustments only when needed, eliminating the need for continuous power-hungry monitoring infrastructure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Reduces power consumption and minimizes clock jitter by digitally controlling the bias current, allowing flexible adaptation to environmental changes and maintaining oscillation amplitude within acceptable ranges.
Implementation Method 1
monitoring an oscillation amplitude of the oscillator at a node using one or more peak detectors
Implementation Method 2
Some electric oscillators use piezoelectric crystals. These oscillators are known as crystal oscillators, in crystal oscillators, the frequency of the periodic signal generated by the circuit is determined by the resonant frequency of the crystal
Implementation Method 3
Electronic oscillators can convert a direct current (DC) power supply to an alternating current (AC) to provide periodic signals at a certain frequency
Data Source
AI summary
Provided is a method for controlling the bias current, IPIERCE, of an oscillator. The method includes acquiring or determining a digital representation encoding a bias current. The method also includes carrying out an algorithm to update the digital representation if the oscillation amplitude is measured, by one or more peak detectors, to be outside of upper and lower thresholds. Also provided is an apparatus arranged to control the bias current of an oscillator using this method, the apparatus including one or more peak detectors and a current digital to analogue converter.