Precharged LC Capacitor Arrangement for Fast Oscillator Startup
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Solution Overview
Problem
In oscillator circuits, particularly in IR-UWB applications, the startup time of ring oscillators is inefficient, leading to high power consumption and phase noise, while LC oscillators require many cycles to reach steady-state amplitude and frequency, affecting the efficiency of frequency synthesizer implementations.
Innovation Solution
An LC circuit with an adjustable capacitive circuit and inductive circuit connected in a loop, where the switching circuit prevents oscillation initially, charges the capacitive circuit, and then enables oscillation by closing the circuit loop, allowing for near-instantaneous startup and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If ring oscillators are used for duty-cycled operation, then instantaneous startup is achieved, but energy efficiency deteriorates due to higher power consumption for a given phase noise level
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitive circuit to a specific voltage level before oscillation begins. This initial charging state is prepared in advance during the duty-cycle off period, so when oscillation starts, the circuit immediately has the energy needed for full-amplitude oscillation without requiring gradual buildup cycles, achieving both fast startup and energy efficiency.
Solution Approach 2:
The patent changes the voltage parameter of the capacitive circuit from a discharged state to a pre-charged state before oscillation begins. By controlling the initial voltage parameter of the capacitive elements, the oscillator achieves instantaneous startup with full amplitude while consuming less energy compared to ring oscillators that require continuous power for immediate operation.
2Use of energy by moving object
If LC oscillators are used for energy efficiency, then power consumption is reduced, but startup time increases due to random phase startup and multiple cycles needed to reach steady-state
Solution Approach 1:
The patent prepares the capacitive circuit in advance by charging it to a specific voltage level before oscillation is needed. This preliminary charging action eliminates the startup delay typical of LC oscillators, as the energy is already stored and ready to immediately sustain full-amplitude oscillation when the switching circuit closes the loop, achieving both energy efficiency and fast startup.
3Use of energy by moving object
If oscillators are duty-cycled to reduce power consumption, then energy efficiency improves, but phase noise increases due to startup transients and frequency instability
Solution Approach 1:
By pre-charging the capacitive circuit to a controlled voltage level before oscillation begins, the patent eliminates startup transients that cause phase noise. The oscillator starts immediately at full amplitude with a clean, stable waveform from the first cycle, avoiding the frequency instability and phase noise associated with gradual amplitude buildup in traditional LC oscillators.
Solution Approach 2:
The patent controls the initial voltage parameter of the capacitive circuit to ensure clean oscillation startup. By setting the initial voltage to a specific value, the oscillator achieves stable frequency and low phase noise from the beginning of operation, maintaining high reliability even during duty-cycled operation where oscillators are frequently started and stopped.
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 reduces power consumption and phase noise by enabling LC oscillators to start quickly and maintain low sensitivity to supply variations, improving the efficiency of oscillator circuits and subsequent RF signal processing circuits.
Implementation Method 1
The adjustable capacitive circuit includes capacitive branch circuits. Each capacitive branch circuit has a respective set of capacitors
Implementation Method 2
The inductive circuit includes one or more inductive elements and a switching circuit
Implementation Method 3
an LC circuit having a capacitive circuit and an inductive circuit connected in a circuit loop
Data Source
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. In a first mode, a switching circuit in the inductive circuit provides a charge voltage across the LC circuit and prevents oscillation of the LC circuit by opening a switch in the circuit loop. In a second mode, the switching circuit enables the oscillation of the LC circuit by closing the switch in the circuit loop. The adjustable capacitive circuit includes capacitive branch circuits configured to contribute a first amount of capacitance when enabled. For each capacitive branch circuit, an initialization circuit couples the set of capacitors to a respective reference voltage in response to the capacitive branch circuit being disabled and the switching circuit operating in the first mode.