LC Oscillator Pre-Charging for Fast Duty-Cycle Startup

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Solution Overview

Problem

In impulse radio ultra-wideband (IR-UWB) communication systems, oscillator circuits face challenges with high power consumption due to startup times, especially in duty-cycled applications where ring oscillators are less energy-efficient and LC oscillators require many cycles to reach steady-state amplitude and frequency.

Innovation Solution

The implementation of an LC oscillator circuit with a switching circuit that allows for near-instantaneous startup by pre-charging the capacitive circuit and enabling oscillation through a switching mechanism, reducing power consumption and phase noise compared to ring oscillators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If LC oscillators are used for duty-cycled operation, then energy efficiency is improved, but startup time increases and reliability deteriorates

Engineering Contradiction:
Improveenergy efficiencyVSAvoidstartup time
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-charging the capacitive circuit before oscillation is needed. The switching circuit charges the capacitor to a predetermined voltage level during the duty cycle off-period, so that when oscillation is required, the oscillator can start immediately with the pre-charged energy already available in the capacitive circuit, eliminating the need for long startup periods.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If ring oscillators are used for duty-cycled operation, then startup time is reduced, but energy consumption increases

Engineering Contradiction:
Improvestartup timeVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the operating parameters of the LC oscillator by dynamically adjusting the charging voltage of the capacitive circuit through the switching circuit. By controlling the voltage level to which the capacitor is charged during the duty cycle off-period, the system optimizes the balance between startup speed and energy consumption, achieving fast startup with lower power than ring oscillators.

Inventive Principle:
Principle #35Parameter changes

3Loss of energy

If LC oscillators operate in duty-cycled mode, then power consumption is reduced, but phase noise increases

Engineering Contradiction:
Improvepower consumptionVSAvoidphase noise
Core Design Contradiction:
Loss of energyVSObject-generated harmful factors

Solution Approach 1:

The pre-charging of the capacitive circuit before oscillation reduces the initial transient period and allows the oscillator to reach steady-state faster, thereby reducing the accumulation of phase noise during startup. The predetermined charge voltage ensures consistent initial conditions that minimize phase noise generation.

Inventive Principle:
Principle #10Preliminary action

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 solution enables LC oscillator circuits to achieve reduced power consumption and lower phase noise, allowing for efficient duty-cycled operation in IR-UWB systems with fast startup times and improved performance in wireless transmission applications.

Implementation Method 1

a capacitive circuit and an inductive circuit connected in a circuit loop... In a first mode, the switching circuit provides a direct-current (DC) charge voltage across the LC circuit

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

In a second mode, the switching circuit enables oscillation of energy between the capacitive circuit and the inductive circuit

Methodology Applied
Scientific EffectLC oscillation: Harmonic Oscillator

Data Source

PatentEP3139497B1Oscillator with favorable startup
Publication Date: 2019.11.27 NXP BV
  • EP3139497B1 patent drawingFigure 1~2
  • EP3139497B1 patent drawingFigure 3
  • EP3139497B1 patent drawingFigure 4

AI summary

In an example embodiment, an apparatus includes an LC circuit having a capacitive circuit and an inductive circuit connected in a circuit loop. The inductive circuit includes one or more inductive elements and a switching circuit. In a first mode, the switching circuit provides a direct-current charge voltage across the LC circuit and prevents oscillation of energy between the capacitive circuit and the inductive circuit by opening a switch in the circuit loop of the LC circuit. In a second mode, the switching circuit enables oscillation of energy between the capacitive circuit and the inductive circuit by closing the switch in the circuit loop.