LC Power Oscillator With Phase-Shifted Feedback for Low-Power RF
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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
A digitally controlled power oscillator with a minimized number of components, using an LC circuit and a phase shift circuit to achieve efficient oscillations, where the pulse shaping circuit allows precise control of oscillation amplitude and minimizes unwanted harmonics, thereby optimizing power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional LC oscillators are used, then oscillation frequency can be achieved, but power efficiency and output signal amplitude vs DC power ratio are poor
Solution Approach 1:
The patent implements a Class-E oscillator that operates with periodic switching action, where the active device (transistor) switches between fully on and fully off states at specific phases of the oscillation cycle. This periodic switching enables the circuit to achieve high power efficiency by minimizing simultaneous voltage and current across the switching device, thereby reducing power dissipation while maintaining high output signal amplitude.
Solution Approach 2:
The patent utilizes reactive impedance transformation through the LC tank circuit and output matching network to transform the load impedance into optimal values at specific frequencies. By changing the reactive parameters (inductance and capacitance values) and their configuration, the circuit achieves impedance matching that maximizes power transfer efficiency and output signal amplitude at the desired operating frequency.
2Adaptability or versatility
If conventional LC oscillators are used, then oscillation can be generated, but they are unsuitable for frequencies below GHz and low power applications
Solution Approach 1:
The patent employs a dynamically adjustable oscillator design where the LC tank circuit parameters can be tuned to achieve stable oscillation across a wide frequency range including sub-GHz frequencies. The circuit incorporates variable inductance or capacitance elements that allow dynamic adjustment of the resonant frequency, enabling reliable operation from low frequencies up to GHz ranges while maintaining low power consumption characteristics.
Solution Approach 2:
The Class-E oscillator circuit is designed to automatically establish and maintain optimal operating conditions through its inherent feedback mechanism. The circuit self-regulates the switching timing and duration based on the tank circuit's resonant characteristics, eliminating the need for complex external control circuits and enabling reliable low-power operation across different frequency ranges including below GHz.
3Measurement precision
If more components are added to improve control, then oscillation amplitude control precision increases, but device complexity increases
Solution Approach 1:
The patent incorporates a feedback mechanism where a portion of the output signal is fed back to the control input of the switching device. This feedback enables automatic regulation of the oscillation amplitude by adjusting the switching duty cycle or timing based on the actual output level, achieving precise amplitude control without requiring additional complex control circuits or multiple active devices.
Solution Approach 2:
The LC tank circuit serves multiple functions simultaneously: it determines the oscillation frequency, provides impedance transformation, and enables amplitude control through its Q-factor and damping characteristics. By making the tank circuit multi-functional, the patent achieves precise oscillation control without adding separate dedicated control components, thereby maintaining device simplicity while improving control precision.
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 high efficiency by minimizing power wastage and allowing precise digital control of oscillation amplitude, improving the output signal amplitude while reducing power consumption and harmonic generation.
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
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AI summary
The present invention concerns an electronic oscillator (1) comprising: an LC resonant circuit (3) comprising an inductive component (4) and a capacitive component (5), the LC resonant circuit (3) being connected to a first reference voltage node (Vdd1) and to an oscillator output node (6); a first transistor (Mn1) connected to the oscillator output node (6) and arranged to periodically operate in a conducting state and a non-conducting state; and a phase shift circuit (9). A phase shift circuit output is connected to the first transistor (Mn1), while a phase shift circuit input is connected by a first feedback circuit (11) to the oscillator output node (6). The phase shift circuit (9) comprises a signal phase shifter (Mnpd) for shifting the phase of a first feedback signal from the first feedback circuit (11) by substantially 180 degrees. The phase shift circuit (9) further comprises a signal adder (12) for adding a first signal from the signal phase shifter (Mnpd) and a second signal to obtain a summed signal; and a second transistor (Mn0) connected to the signal adder (12) for mirroring the summed signal to the oscillator output node (6) through the first transistor (Mn1).