Crystal Oscillator Load Capacitance Boost via Miller Multiplication
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Solution Overview
Problem
Crystal oscillators face challenges in maintaining stable oscillation due to variations in transconductance caused by load capacitance changes, especially in ultra-low power applications, leading to issues with oscillation starting and yield.
Innovation Solution
A crystal oscillator design incorporating a Miller multiplication circuit that increases load capacitance by connecting a Miller multiplication circuit in parallel to the load capacitor, providing a larger oscillatable transconductance area and adjusting capacitance to optimize oscillation starting and frequency adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If load capacitance is increased to provide larger oscillatable transconductance area, then oscillation starting stability is improved, but circuit area and cost increase
Solution Approach 1:
The Miller multiplication circuit acts as an intermediary between the physical load capacitor and the oscillation circuit. It uses the Miller effect to create a virtual capacitance that is (A+1) times the physical capacitor value, where A is the gain of the Miller circuit. This allows the system to enjoy the benefits of large capacitance without the penalty of large physical area.
Solution Approach 2:
The invention changes the effective capacitance parameter through the Miller multiplication mechanism. By controlling the gain A of the Miller multiplication circuit, the effective load capacitance can be dynamically adjusted to (A+1) times the physical capacitor value, providing flexibility in optimizing oscillation starting stability without proportionally increasing circuit area.
2Reliability
If load capacitance is increased to ensure proper oscillation, then oscillation reliability is improved, but power consumption increases
Solution Approach 1:
The Miller multiplication circuit serves as an intermediary that decouples the relationship between physical capacitor size and effective capacitance. This allows the system to achieve high oscillation reliability through virtual capacitance multiplication while keeping the physical components and their associated power consumption minimal.
Solution Approach 2:
The invention enables independent control of effective capacitance from physical capacitance through the Miller gain parameter A. This parameter separation allows optimization of oscillation reliability without proportionally increasing power consumption, as the Miller circuit uses active components with low power draw compared to large passive capacitors.
3Area of stationary object
If physical load capacitor size is reduced to save area, then circuit integration is improved, but oscillation starting stability deteriorates
Solution Approach 1:
The Miller multiplication circuit acts as a mediator that compensates for the reduced physical capacitance. Even though the physical capacitor is small, the Miller circuit multiplies its effect by (A+1) times, thereby maintaining sufficient oscillation starting stability while achieving compact circuit integration.
Solution Approach 2:
The invention changes the effective capacitance parameter through Miller multiplication, allowing small physical capacitors to provide large effective capacitance values. By adjusting the Miller gain A, the system can maintain oscillation starting stability with minimized physical capacitor area.
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
This design enhances the stability and reliability of oscillation starting, reduces circuit costs, and allows for more efficient power consumption, particularly in low-power applications.
Implementation Method 1
a first Miller multiplication circuit, where an input terminal and an output terminal of the first Miller multiplication circuit are respectively connected to two terminals of the first load capacitor, and the first Miller multiplication circuit is configured to increase a first load capacitance of the oscillating circuit
Implementation Method 2
a crystal oscillator is a crystal element packaged with a quartz crystal and an oscillating circuit thereof, and can use the piezoelectric effect to provide stable and precise single-frequency oscillations in a state of resonance
Data Source
AI summary
Disclosed are a crystal oscillator, a chip, and an electronic device. The crystal oscillator includes: an oscillating circuit, including: a crystal, an amplification circuit, a first load capacitor, and a second load capacitor, where the first load capacitor and the second load capacitor are respectively connected to a first terminal and a second terminal of the crystal; and a first Miller multiplication circuit, where an input terminal and an output terminal of the first Miller multiplication circuit are respectively connected to two terminals of the first load capacitor, and the first Miller multiplication circuit is configured to increase a first load capacitance of the oscillating circuit, where the first load capacitance is a capacitance between the first terminal of the crystal and the ground. According to this technical solution, an area occupied by the load capacitor as well as circuit costs can be reduced.