Programmable Crystal Oscillator Startup With Dynamic Load Capacitance
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Solution Overview
Problem
Crystal oscillator circuits, such as Pierce oscillators, require significant time and energy to start oscillating, which is inefficient in battery-powered applications and reduces battery life.
Innovation Solution
The implementation of programmable load capacitors and an amplifier with a bias current generator that adjusts capacitance values and bias current during startup to reduce the time and energy required for oscillation initiation, followed by setting to optimal values for normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the crystal oscillator circuit uses fixed load capacitors for stable oscillation, then the oscillation stability is improved, but the startup time and energy consumption increase
Solution Approach 1:
The patent applies dynamics by making the load capacitor values changeable over time. During startup, the load capacitors are set to lower values to reduce the critical transconductance and enable faster oscillation buildup. After startup, the capacitor values are switched to higher values to maintain stable oscillation. This time-varying capacitance approach resolves the contradiction between fast startup and stable oscillation.
Solution Approach 2:
The patent changes the electrical parameters (capacitance values) of the load capacitors based on the operational phase. By adjusting the capacitance values dynamically - lower during startup and higher during normal operation - the system optimizes both startup speed and oscillation stability, directly addressing the technical contradiction.
2Stability of the object's composition
If the crystal oscillator circuit uses fixed load capacitors for stable oscillation, then the oscillation stability is improved, but the energy consumption increases
Solution Approach 1:
The patent makes the load capacitor values dynamic rather than fixed. During startup, lower capacitance values are used which require less energy to charge and discharge. After startup, the capacitance values are increased for stability. This dynamic adjustment reduces overall energy consumption while maintaining oscillation stability during normal operation.
Solution Approach 2:
The patent changes the capacitance parameter based on operational requirements. By using lower capacitance values during startup and switching to higher values only when needed for stability, the system minimizes energy consumption throughout the oscillator's operation lifecycle while ensuring stable oscillation when required.
3Speed
If the bias current is increased to reduce startup time, then the startup speed is improved, but the power consumption increases
Solution Approach 1:
The patent applies periodic action by using a high bias current only during the startup phase and then switching to a lower bias current for normal operation. This time-dependent current adjustment allows fast startup without sustaining high power consumption, resolving the contradiction between startup speed and power usage.
Solution Approach 2:
The patent changes the bias current parameter based on the operational phase. A higher bias current is applied during startup to accelerate oscillation buildup, then the current is reduced to a lower level for normal operation. This parameter adjustment optimizes both startup performance and overall power consumption.
Data Source
AI summary
In one embodiment, a method of programming an oscillator circuit includes providing a resonator, a first programmable capacitor, a second programmable capacitor, and an amplifier. The first programmable capacitor and the second programmable capacitor may be programmed at a first capacitance value during a first time period, wherein the first programmable capacitor provides a first voltage to bias the resonator and the amplifier alters the second voltage to provide a third voltage to the resonator. During a second time period the first capacitance value is increased.