LC Oscillator Phase-Shift Circuit for Low-Power Harmonic Control
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Solution Overview
Problem
Existing LC oscillators are unsuitable for frequencies below GHz and low power/low cost transmitter applications, and they do not provide a good output signal amplitude vs direct current power ratio.
Innovation Solution
An electronic oscillator design that incorporates an LC resonant circuit connected to a reference voltage node and an oscillator output node, with a first transistor and a phase shift circuit that includes a signal phase shifter and adder to achieve 180-degree phase shift, minimizing power wastage and allowing for digital control of oscillation amplitude, thereby reducing harmonic generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional LC oscillators are used, then the circuit can generate oscillations, but the output signal amplitude vs direct current power ratio is poor
Solution Approach 1:
The patent implements periodic switching of the transistor between conducting and non-conducting states to generate oscillations. This periodic action allows the oscillator to build up signal amplitude efficiently while consuming power only during specific phases of the oscillation cycle, thereby improving the output signal amplitude vs DC power ratio and reducing overall power consumption.
Solution Approach 2:
The patent changes the operating parameters of the transistor by switching between different states (conducting/non-conducting) and uses feedback circuits to dynamically adjust the phase and amplitude. This parameter modulation enables efficient energy transfer to the LC tank circuit, improving power conversion efficiency and reducing wasted power.
2Speed
If conventional LC oscillators are used, then oscillations can be sustained, but they are unsuitable for frequencies below GHz
Solution Approach 1:
The patent employs dynamic switching of the transistor and uses feedback circuits that can adapt to different operating conditions. This dynamic operation allows the oscillator to maintain stable oscillations across a wide frequency range including below GHz frequencies, where conventional oscillators fail to operate effectively.
3Object-generated harmful factors
If conventional LC oscillators are used, then oscillations are generated, but unwanted harmonics are produced
Solution Approach 1:
The patent incorporates feedback circuits that monitor the output signal and adjust the input to the LC tank circuit accordingly. This feedback mechanism suppresses unwanted harmonics by canceling them out or preventing their generation, thereby improving signal quality and reducing harmful electromagnetic emissions while maintaining reliable oscillation.
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 proposed oscillator is highly efficient, minimizes power consumption, and can be implemented with few components, enabling precise control of oscillation amplitude and improved signal quality by reducing unwanted harmonics.
Implementation Method 1
An LC circuit, also called a tank circuit, resonant circuit, or tuned circuit, is an electric circuit comprising an inductive component, such as an inductor, represented by the letter L, and a capacitive component, such as a capacitor, represented by the letter C, connected in parallel, for example. The circuit can act as an electrical resonator storing energy oscillating at the circuit's resonant frequency.
Implementation Method 2
Due to electromagnetic induction, the inductor generates a back electromotive force equal to L(di/dt) in order oppose the change in current.
Data Source
AI summary
The present invention concerns an electronic oscillator comprising: an LC resonant circuit comprising an inductive component and a capacitive component, the LC resonant circuit being connected to a first reference voltage node and to an oscillator output node; a first transistor connected to the oscillator output node and arranged to periodically operate in a conducting state and a non-conducting state; and a phase shift circuit. A phase shift circuit output is connected to the first transistor, while a phase shift circuit input is connected by a first feedback circuit to the oscillator output node. The phase shift circuit comprises a signal phase shifter for shifting the phase of a first feedback signal from the first feedback circuit by substantially 180 degrees. The phase shift circuit further comprises a signal adder for adding a first signal from the signal phase shifter and a second signal to obtain a summed signal; and a second transistor connected to the signal adder for mirroring the summed signal to the oscillator output node through the first transistor.