Phase Adjustment Circuit With LC-VCO for Wideband Phase Control
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Solution Overview
Problem
Existing phase adjustment circuits are limited in their frequency range and require conventional Quadrature-VCOs, which are difficult to use in certain devices, and 90-degree hybrids operate only at specific frequencies.
Innovation Solution
A phase adjustment circuit utilizing an LC-VCO as the clock generation unit, with feedback mechanisms involving multiplying, adding, and low-pass filtering units to control amplitude, allowing for arbitrary phase differences and maintaining constant output amplitude without an automatic gain control unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a Quadrature-VCO is used as the clock generation unit, then sine waves with a fixed phase difference of π/2 can be generated, but the oscillation frequency is limited and it is difficult to use in the limit region of a device
Solution Approach 1:
The patent changes the fundamental parameter of the clock generation unit from a Quadrature-VCO (which has limited frequency range) to an LC-VCO (which can operate across a wide frequency range). This parameter change enables the system to achieve wide frequency adaptability while maintaining the ability to generate the required sine wave signals with appropriate phase relationships through the subsequent signal processing circuitry.
2Adaptability or versatility
If a 90 degree hybrid is used to produce sine waves with a fixed phase difference of π/2, then the phase relationship is maintained, but it operates only at a specific frequency
Solution Approach 1:
The patent replaces the static 90-degree hybrid (which is frequency-specific) with a dynamic system using an LC-VCO and programmable gain amplifiers. The phase relationship is maintained dynamically through digital control of the gain parameters rather than through a fixed frequency-dependent component, enabling frequency agility while maintaining phase accuracy through digital programming.
Solution Approach 2:
The patent substitutes the mechanical/physical 90-degree hybrid component with a combination of electronic components (LC-VCO, multipliers, programmable gain amplifiers) and digital control. This substitution allows the system to achieve both wide frequency range and programmable phase control, replacing the frequency-specific physical component with a programmable electronic system.
3Adaptability or versatility
If conventional phase adjustment circuits are used, then phase adjustment can be performed, but the output amplitude varies with frequency and requires automatic gain control
Solution Approach 1:
The patent implements a feedback mechanism where the output amplitude is detected and fed back to the programmable gain amplifiers. The gain parameters are automatically adjusted based on the detected amplitude to maintain constant output level across different frequencies. This feedback loop eliminates the need for external automatic gain control while maintaining constant amplitude output.
Data Source
AI summary
An embodiment is a phase adjustment circuit includes a sine wave output circuit, a first multiplier, a second multiplier, and an adder. The sine wave output circuit is configured to output two sine wave signals of a fixed phase difference. The first multiplier is configured to multiply an amplitude of a first sine wave signal output from the sine wave output circuit by a first variable to generate a first output signal. The second multiplier is configured to multiply an amplitude of a second sine wave signal output from the sine wave output circuit by a second variable to generate a second output signal. The adder is configured to add the first output signal from the first multiplier and the second output signal from the second multiplier.