Parallel Phase-Shifting Delay Line for Low Group-Delay Deviation
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Solution Overview
Problem
Existing RF signal processing technologies face challenges in maintaining low group-delay deviation over a wide frequency range while minimizing losses, especially in high-power applications, due to the accumulation of losses in serial connections and inefficiencies in switching technologies.
Innovation Solution
The use of a microstrip transmission line in parallel with a high-pass structure, where switches are used only to connect the high-pass structure in parallel, reducing losses to 0.1 dB and allowing for adjustable phase shifts without additional serial switches, and the coordination of transmission line length and capacitor/inductor values to achieve low group delay deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If serial switches are used to connect delay lines in high-power applications, then phase shifting capability is achieved, but losses accumulate to 1 dB per delay cell
Solution Approach 1:
The patent inverts the conventional switching architecture by using a single shunt switch connected to ground rather than serial switches in the signal path. This inversion eliminates the accumulation of switching losses while maintaining phase shifting capability through controlled grounding of transmission line sections.
Solution Approach 2:
The patent extracts the switching function from the signal path by using shunt switches connected to ground rather than series switches. This separation removes the harmful effect of switching losses from the main signal transmission path while preserving the phase control function.
2Adaptability or versatility
If multiple serial switching cells are used for multi-phase-shift applications, then phase shifting range is increased, but overall loss increases due to accumulation
Solution Approach 1:
The patent segments the phase shifting function into multiple independent shunt switch cells that can be independently controlled. Each cell provides a portion of the total phase shift, and their combined effect achieves the desired phase shifting range without the losses accumulating as they would in series connections.
Solution Approach 2:
The patent merges multiple phase shifting functions into a parallel architecture where multiple shunt switch cells operate simultaneously on the same signal path. This combining approach allows the system to achieve wide phase shifting range while maintaining low overall loss since all cells share the same signal path rather than being in series.
3Ease of operation
If switches are placed in series to control delay lines, then phase shift control is achieved, but losses are in the range of 0.5 dB per switch
Solution Approach 1:
The patent introduces ground as an intermediary reference point for the shunt switches. By switching to ground rather than switching the signal path directly, the switches operate in a lower voltage potential, reducing power consumption and losses while maintaining effective phase control through the transmission line impedance interaction.
Data Source
AI summary
A delay line includes one or more phase-shifting cells, where each phase-shifting cell includes a high-pass filter circuit that may be selectively coupled to or decoupled from a transmission line. The filter circuit is couplable in parallel with the transmission line and shifts a signal conveyed through the transmission line by a predetermined phase angle. The high-pass filter circuit includes one or more capacitors and one or more reactance elements (e.g., inductors). The selective coupling may be achieved using multi-gate transistors.