Crystal Oscillator Kick-Start Circuit for Faster Power-Up
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Solution Overview
Problem
Crystal oscillator circuits in high-frequency applications, such as those in the mmW frequency band, face challenges with prolonged start-up times and increased power consumption due to high phase noise and parasitic oscillations, which are not adequately addressed by existing solutions.
Innovation Solution
A crystal oscillator circuit with a differential pair of transistors configured in a cross-coupled mode and a kick-start circuit that injects pulses during start-up to reduce start-up time and minimize parasitic oscillations, utilizing a complementary differential pair for current reuse and disconnecting load capacitance during start-up to reduce dynamic power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the crystal oscillator operates at higher frequency to meet mmW carrier frequency requirements, then the phase noise is amplified and power consumption increases, but the start-up time becomes excessively long
Solution Approach 1:
The kick-start circuit applies preliminary action by injecting start-up pulses into the crystal oscillator before normal operation begins. These pulses pre-excite the crystal resonator, causing it to reach oscillation threshold faster and significantly reducing the start-up time from cold state.
Solution Approach 2:
The kick-start circuit employs periodic action by delivering a sequence of pulses at a specific frequency and duty cycle. This periodic excitation builds up oscillation amplitude progressively, enabling the crystal oscillator to reach stable operation faster than continuous excitation would allow.
2Productivity
If the crystal oscillator operates at higher frequency to reduce transmission unit duration, then the energy drawn during start-up surpasses energy used during actual transmission
Solution Approach 1:
The kick-start circuit performs preliminary action by pre-charging the crystal resonator with controlled pulses, reducing the time the oscillator needs to draw full power. This preliminary excitation allows the system to reach operational state faster, thereby reducing total start-up energy consumption.
Solution Approach 2:
The system changes operational parameters by switching between kick-start mode (with pulses) and normal operation mode. During kick-start, the duty cycle and frequency are optimized for rapid excitation, while in normal operation, standard parameters apply, thus optimizing energy efficiency across different operational phases.
3Loss of time
If the crystal oscillator is designed for fast power-up to match reduced transmission unit duration, then parasitic oscillations and phase noise increase
Solution Approach 1:
The kick-start circuit applies preliminary action with carefully controlled pulses that excite the crystal at its resonant frequency. By matching the pulse frequency to the crystal's natural resonance, the circuit builds up legitimate oscillations efficiently while minimizing excitation of parasitic modes through proper pulse width and amplitude control.
Solution Approach 2:
The system incorporates feedback mechanisms to monitor oscillation amplitude and frequency during start-up. This feedback allows the kick-start circuit to adjust pulse parameters dynamically, ensuring that energy is directed into the desired oscillation mode while suppressing parasitic oscillations that may arise during the transition to stable operation.
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
The solution significantly decreases start-up time and power consumption of crystal oscillator circuits, making them suitable for high-frequency applications while reducing parasitic oscillations, thus enhancing their performance in GHz regime operations.
Implementation Method 1
a kick-start circuit configured to inject a number of pulses into said crystal during a start-up period of the crystal oscillator circuit
Data Source
Figure 1~2
Figure 3~5
Figure 6a~7
AI summary
A crystal oscillator circuit comprises a crystal (X1); oscillator circuitry (31) for generating a crystal oscillation signal at an oscillation frequency; and a kick-start circuit (12) for injecting pulses into the crystal during a start-up period. The oscillator circuitry (31) comprises a differential pair of transistors (M1, M2) and can operate in an oscillating mode or a start-up mode. In the oscillating mode, the differential pair of transistors are cross-coupled so that a gate terminal of one transistor (M-1) is coupled to a drain terminal of the other transistor (M2), and vice versa, and the drain terminals are coupled to the crystal (X-1) to generate the crystal oscillation signal. In the start-up mode, the kick-start circuit (12) drives the gate terminals of the transistors (M-1, M2) with said pulses. This crystal oscillator circuit has a decreased start-up time compared to prior art solutions and a reduced influence of parasitic oscillations.