Phase Shift Circuit Using 90° Hybrid and Balun for 360° Range
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Solution Overview
Problem
Existing phase shift circuits can only achieve a phase shift of approximately 180°, which is insufficient to obtain a desired phase over 360°, limiting their application in high-frequency signal processing.
Innovation Solution
A phase shift circuit configuration incorporating a 90° hybrid circuit, variable capacitors, a balun circuit, and a switch circuit, which allows for phase shift adjustments over 360° by combining two modes of operation, and includes a resistor unit for termination processing and low pass/high pass filters to reduce size and enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a 90° hybrid circuit with variable capacitors and inductors is used, then phase shift adjustment is enabled, but the adjustable phase range is limited to approximately 180°
Solution Approach 1:
The phase shift circuit is segmented into two identical 90° hybrid circuit blocks, each capable of providing 0° to 180° phase shift. By dividing the total 360° phase shift requirement into two 180° segments, the circuit achieves extended phase range while maintaining the simplicity of each individual block.
Solution Approach 2:
Two 90° hybrid circuit blocks are merged in series, with the output of the first block connected to the input of the second block. The combined phase shift capability of both blocks provides the desired 360° adjustable phase range, where each block contributes 0° to 180° of phase shift.
2Adaptability or versatility
If the phase range is extended to 360° by combining two modes, then desired phase over 360° is obtained, but circuit configuration complexity increases
Solution Approach 1:
The balun circuit serves multiple functions: it converts single-ended signals to differential signals, provides 180° phase shift between its two output terminals, and enables switching between two operational modes. This multi-functionality reduces the need for additional dedicated components.
Solution Approach 2:
The switch circuit dynamically connects the input signal to different paths based on the desired phase shift range. By switching between connecting the input to the first balanced signal output terminal or the second balanced signal output terminal, the circuit adapts to provide phase shifts across the full 360° range.
3Volume of moving object
If lumped constant elements are used in the balun circuit, then circuit size is reduced, but frequency response may be limited
Solution Approach 1:
The lumped constant elements (capacitors and inductors) in the balun circuit are designed with specific parameter values optimized for the target communication frequency band. By carefully selecting these parameters, the circuit achieves both compact size and accurate frequency response for the intended application range.
Data Source
AI summary
A phase shift circuit includes a 90° hybrid circuit, variable capacitors, a switch circuit, and a balun circuit. The 90° hybrid circuit includes a high-frequency signal input terminal and a high-frequency signal output terminal. The variable capacitors are respectively connected to between first and second variable capacitor connection terminals of the 90° hybrid circuit and the ground. The balun circuit includes an unbalanced signal input terminal and balanced signal output terminals formed by a pair of terminals. The switch circuit selects any one of the balanced signal output terminal and the balanced signal output terminal of the balun circuit and connects the selected terminal to the high-frequency signal input terminal to the 90° hybrid circuit.