Oscillator Drive Circuit With Inductor Energy Injection
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Solution Overview
Problem
Existing drive circuits for crystal oscillators are inefficient in terms of power consumption due to out-of-phase current flow and significant current spikes during switching transitions, leading to energy dissipation in transistors and suboptimal operation.
Innovation Solution
A drive circuit utilizing a switching circuit with an NMOS and PMOS transistor pair, where energy is stored in a drive inductor and injected synchronously with the oscillator's oscillations, avoiding short-circuit currents and ensuring in-phase operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional inverter drive circuit is used to drive the crystal oscillator, then the oscillator can be driven, but power consumption increases due to out-of-phase current flow and switching transition current spikes
Solution Approach 1:
The drive inductor is pre-charged during the first phase when the oscillator is not receiving energy, storing energy in advance. This pre-stored energy is then injected during the second phase when the oscillator needs energy, avoiding the need for continuous current flow and reducing power consumption.
Solution Approach 2:
The drive circuit operates in periodic phases: a first phase where the drive inductor is charged and the oscillator is not driven, and a second phase where the stored energy is injected to the oscillator. This periodic operation eliminates continuous power dissipation and reduces average power consumption.
Solution Approach 3:
The drive inductor acts as an intermediary energy storage element between the voltage source and the oscillator. It temporarily stores energy and releases it at the appropriate phase, enabling synchronous energy injection and avoiding direct current flow through the transistors during the entire cycle.
2Reliability
If the drive circuit operates continuously to drive the oscillator, then the oscillator maintains stable operation, but current spikes occur during switching transitions causing additional power loss
Solution Approach 1:
The switching circuit is designed to ensure that the NMOS and PMOS transistors are never on simultaneously. The drive inductor is pre-charged before the switching transition, so that when the transistors switch, there is no sudden current spike because the energy is already stored in the inductor's magnetic field.
Solution Approach 2:
The drive inductor serves as an intermediary that smooths the current flow during switching transitions. By storing energy in its magnetic field during the first phase and releasing it during the second phase, it prevents abrupt current changes and eliminates harmful current spikes that would otherwise occur during transistor switching.
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 enhances energy efficiency by storing and delivering energy in phase with the oscillator's cycles, reducing power dissipation and improving the overall efficiency of the drive circuit operation.
Implementation Method 1
a drive circuit for driving an oscillator (3), comprising a voltage source (13) connected between a first terminal of a drive inductor (L D) and ground, wherein energy is stored in the drive inductor and injected synchronously with the oscillator's oscillations
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention concerns a drive circuit (11) for driving an oscillator (3). The drive circuit (11) comprises a first inductor (LD) comprising a first terminal and a second terminal; an electrical energy source (13) connected to the first terminal; and a switching circuit connected to the second terminal and to the oscillator. The switching circuit is configured to operate at least in an off state, where it is configured not to feed electrical energy to the oscillator (3), and in an on state, where it is configured to feed electrical energy to the oscillator (3). The first inductor (LD) is arranged to store energy in its magnetic field when the switching circuit is in the off state, and, when the switching circuit is in the on state, the switching circuit is arranged to use at least some of the energy stored in the magnetic field to deliver a surge of current from the electrical energy source (13) to the oscillator (3).