LC Frequency Synthesizer Amplitude Control for Fast Phase-Aligned Startup
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Solution Overview
Problem
Frequency synthesizer implementations in IR-UWB radios face challenges due to long startup times and unpredictable startup phases of LC oscillators, which hinder efficient duty-cycled operation and power management.
Innovation Solution
A frequency synthesizer device with an LC tank circuit and auxiliary circuits that adjust transconductance gain, using a calibration circuit to detect output signal amplitude and enable/disabling auxiliary circuits to maintain constant oscillation amplitude across a wide frequency range, enabling fast startup and phase alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If LC oscillators are used in duty-cycled mode, then power consumption is reduced, but startup time becomes excessively long and startup phase becomes unpredictable
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitive element to a known voltage level before the oscillation burst begins. This pre-charge operation prepares the oscillator in advance, enabling it to start oscillating immediately when the burst is initiated, thereby eliminating the long startup time while maintaining low power consumption during the duty-cycled operation.
Solution Approach 2:
The patent segments the oscillator operation into distinct phases: a pre-charge phase where the capacitive element is charged to a known voltage, and a burst phase where oscillation occurs. This segmentation allows the oscillator to be prepared in advance (reducing startup time) while remaining dormant during idle periods (reducing power consumption).
2Use of energy by stationary object
If LC oscillators are used in duty-cycled mode, then power consumption is reduced, but startup phase becomes unpredictable
Solution Approach 1:
The patent sets the initial phase by pre-charging the capacitive element to a specific voltage level before oscillation begins. This preliminary action determines the starting phase point of the oscillation, making it predictable and controllable rather than random, while still allowing the oscillator to be turned off during idle periods to save power.
Solution Approach 2:
The patent controls the startup phase by adjusting the pre-charge voltage level applied to the capacitive element. By changing this voltage parameter before oscillation begins, the initial phase of the oscillation can be precisely controlled, enabling phase alignment requirements to be met while maintaining duty-cycled operation for power efficiency.
3Loss of time
If ring oscillators are used instead of LC oscillators, then startup time is reduced, but frequency tuning range and precision are limited
Solution Approach 1:
The patent introduces an intermediary mechanism (the pre-charge circuit and controlled switching arrangement) that enables the LC oscillator to achieve fast startup characteristics similar to ring oscillators. This intermediary preparation phase allows the LC oscillator to start immediately when needed, while the LC tank circuit itself maintains its superior frequency tuning capabilities.
Solution Approach 2:
The patent makes the LC oscillator dynamic by enabling it to switch between a dormant state (capacitor charged, oscillation suppressed) and an active oscillation state. This dynamic operation allows the oscillator to have both fast startup (like ring oscillators) and continuous frequency tuning capability (like traditional LC oscillators), adapting its behavior to different operational requirements.
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 achieves near-instantaneous startup with known phase orientation, low power consumption, and efficient frequency locking, addressing the inefficiencies and inaccuracies of traditional LC oscillators in duty-cycled modes.
Implementation Method 1
an oscillator circuit with an inductive-capacitive (LC) tank circuit. The LC tank circuit includes a capacitive element, and an inductive element that is connected to the capacitive element
Implementation Method 2
Driver circuits are configured to reinforce oscillation to generate output signal that oscillates in response to voltage applied to the tank circuit and a transconductance gain provided to the oscillator circuit
Implementation Method 3
A plurality of auxiliary circuits are each configured to adjust, in response to being enabled, an amplitude of the output signal by changing the transconductance gain provided to the oscillator circuit
Data Source
AI summary
A frequency synthesizer device provides amplitude control. Using switch circuit operating in a first mode, a charge voltage is applied to an oscillator circuit that an inductive-capacitive (LC) tank circuit. The LC tank circuit has a capacitive element, and an inductive element that is connected to the capacitive element. Using the switch circuit operating in a second mode, the LC tank circuit is enabled to oscillate. Using driver circuits that are response to a voltage applied to the tank circuit, current is reinforced in the LC tank, and the reinforcement is based upon a transconductance gain of the driver circuits. Using a calibration circuit, an amplitude of an output signal from the oscillator circuit is detected. In response to the detected amplitude, the transconductance gain is adjusted by enabling or disabling auxiliary circuits from plurality of auxiliary circuits.