Phase Shifter Circuit for Linear Digital Phase Control
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Solution Overview
Problem
Existing phase shift circuits using active elements fail to generate an output signal with a desired phase due to non-linear changes in the phase of the output signal in response to control signals.
Innovation Solution
A phase shifter design that includes a signal generator, a controller, a vector adder, and a digital-to-analog converter, which generates in-phase and quadrature phase signals and adjusts their magnitudes based on control signals to achieve linear phase shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a phase shift circuit using active elements is used, then the circuit can generate output signals with adjusted phases, but the phase change is non-linear with respect to control signals
Solution Approach 1:
The phase shifter divides the phase adjustment into multiple discrete steps using a plurality of switching elements (first to fourth switching elements) connected in parallel. Each switching element corresponds to a specific phase shift amount, allowing the total phase shift to be constructed by selectively activating individual segments. This segmentation enables linear phase control by summing discrete phase contributions.
Solution Approach 2:
The invention employs switching elements that can be dynamically controlled to connect or disconnect signal paths based on control signals. The switching elements change the circuit configuration in real-time, enabling dynamic phase adjustment. The phase shift amount is controlled by selectively activating specific switching elements through control signals, providing dynamic and linear phase control.
2Ease of operation
If active elements are used for phase shifting, then phase control is possible, but the relationship between control signal and output phase is non-linear
Solution Approach 1:
The invention changes the control parameter from continuous analog control to discrete digital control. Each switching element is associated with a specific binary weight (e.g., 1, 2, 4, 8 bits), and the control signals are digital values that directly correspond to specific phase shift amounts. This parameter change enables linear relationship between control signal value and output phase, improving phase shift accuracy.
3Device complexity
If a simple phase shift circuit is used, then the circuit structure is simple, but it cannot achieve linear phase shifting
Solution Approach 1:
The invention merges multiple switching elements in parallel, where each element contributes to the overall phase shift. The signal paths through different switching elements are combined at a common output node, creating a composite phase-shifted signal. This merging approach achieves linear phase shifting through the superposition of individual phase contributions while maintaining a relatively compact circuit structure.
Data Source
AI summary
Disclosed is a phase shift circuit including an input circuit for generating first to fourth internal signals based on an in-phase signal, a complementary in-phase signal, a quadrature phase signal, and a complementary quadrature phase signal and a switching circuit for outputting first to fourth shift signals based on the first to fourth internal signals. The input circuit includes a first transistor connected between a ground node and a first node to operate based on the in-phase signal and the first bias signal, a second transistor connected between the ground node and a second node to operate based on the complementary in-phase signal and the first bias signal, a third transistor connected between the ground node and the first node to operate based on the second bias signal, and a fourth transistor connected between the ground node and the second node to operate based on the second bias signal.