Differential Phase Adjustment Circuit for Wide-Frequency Clocking
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Solution Overview
Problem
Conventional phase adjustment circuits using Quadrature-VCOs and 90-degree hybrids are limited in frequency range and operation, making them unsuitable for wide-frequency applications.
Innovation Solution
A phase adjustment circuit utilizing a clock generation unit, variable amplifiers, differential transmission lines, and terminal circuits, which eliminates the need for Quadrature-VCOs, allowing for a wide range of frequency usage by employing LC-VCOs and differential transmission lines with specific length and propagation speed characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a Quadrature-VCO is used to generate sine waves with a fixed phase difference of π/2, then the phase adjustment circuit can generate intermediate phase waveforms, but the oscillation frequency is limited and it becomes difficult to use in the limit region of the device
Solution Approach 1:
The patent changes the fundamental operating parameters by replacing the Quadrature-VCO with an LC-VCO that can operate at higher frequencies. The invention uses a 90-degree hybrid circuit to generate quadrature signals at the desired high frequency, fundamentally changing the frequency generation approach to enable operation in the device's limit region while maintaining phase adjustment capability
Solution Approach 2:
The patent substitutes the voltage-controlled oscillation mechanism with a different approach using LC resonance circuits and 90-degree hybrid circuits. This replacement allows the system to achieve quadrature signal generation at frequencies where the original VCO mechanism becomes unreliable, effectively replacing a mechanical/electrical control system with a resonance-based system
2Adaptability or versatility
If a 90 degree hybrid is used to produce a sine wave having a fixed phase difference of π/2, then the phase adjustment can be achieved, but it operates only at a specific frequency
Solution Approach 1:
The patent makes the 90-degree hybrid circuit functional across multiple frequencies by combining it with an LC-VCO that can be tuned to different frequencies. The hybrid circuit serves multiple purposes: generating quadrature signals at the VCO frequency, enabling phase adjustment, and maintaining operation across a wide frequency range, thus achieving universal applicability
3Measurement precision
If conventional phase adjustment circuits are used, then phase control can be achieved, but the circuit area and cost increase
Solution Approach 1:
The patent merges multiple functions into integrated circuit blocks: the LC-VCO generates both the carrier and quadrature signals, the 90-degree hybrid combines signal paths, and the phase adjustment circuit integrates variable amplifiers and adders. This consolidation reduces the overall circuit area while maintaining phase control accuracy through coordinated operation of the merged components
Data Source
AI summary
In some embodiments, the phase adjustment circuit includes a clock generator that is configured to generate a sinusoidal clock signal, and may include a variable amplifier that is configured to receive the clock signal output from the clock generator as an input, output an amplitude-adjusted sinusoidal differential clock signal, and output an amplitude-adjusted in-phase signal. The phase adjustment circuit may include an adder that is configured to output a differential signal obtained by adding the in-phase signal to each of a positive phase side and a negative phase side of the differential clock signal output from the variable amplifier, a differential transmission line that includes two transmission lines configured to transmit the differential signal output from the adder, and a terminal circuit that is configured to terminate the differential transmission line where a signal is output from a terminal of any one of the two transmission lines.