Variable Phase Shifter-Attenuator High Resolution Control
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Solution Overview
Problem
Existing variable phase-shifter-attenuators lack the ability to provide high-resolution phase shift over a wide range of attenuations, often sacrificing phase accuracy as attenuation increases, and fail to offer a sufficient number of discrete phase shift-attenuation states.
Innovation Solution
A digitally controlled phase shifter-attenuator system that combines a phase rotator with a switchable bias circuit or attenuator, using a digital word to select from a large number of phase shift-attenuation states distributed over various attenuation ranges, maintaining high phase resolution across a wide range of attenuations by adjusting the dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional variable phase-shifter-attenuator is used, then it can provide phase shift and attenuation functions, but it sacrifices phase accuracy as attenuation increases and cannot provide high-resolution phase shift over a wide range of attenuations
Solution Approach 1:
The device is divided into two functional sections: a phase shifter section that provides fine phase resolution and a switchable attenuator section that provides coarse attenuation control. This segmentation allows each section to optimize its function independently, maintaining high phase resolution while achieving wide attenuation range.
Solution Approach 2:
A switchable attenuator is introduced as an intermediary component between the input signal and the phase shifter. This intermediary element handles the coarse attenuation function, allowing the phase shifter to focus on providing high-resolution phase control without being degraded by large attenuation variations.
2Adaptability or versatility
If the number of discrete phase shift-attenuation states is increased, then more control options are available, but the device complexity increases
Solution Approach 1:
By segmenting the control into two independent parts (phase shifter control and attenuator control), the total number of discrete states becomes the product of the states in each section. This allows a large number of combined states to be achieved while keeping each individual section relatively simple.
Solution Approach 2:
The switchable attenuator dynamically adjusts the signal level before it enters the phase shifter section. This dynamic control allows the system to adapt the number of available phase states based on the selected attenuation level, providing more states when larger attenuations are selected and fewer states when smaller attenuations are selected.
3Ease of manufacture
If a fixed dynamic range is used in the phase rotator, then the circuit design is simplified, but the phase resolution cannot be maintained over a wide range of attenuations
Solution Approach 1:
The phase rotator's dynamic range is made switchable rather than fixed. The attenuator section can switch between different dynamic range settings, allowing the phase rotator to operate optimally in each range. This maintains phase resolution consistency across the full attenuation range while keeping the circuit design relatively simple through shared components.
Data Source
AI summary
A phase shifter-attenuator system having: a controller for producing a digital word representative of a predetermined phase shift and attenuation provided to an input signal; and a phase shifter-attenuation section. The phase shifter-attenuation section includes: a phase rotator for providing one of a plurality combinations of phase shifts-attenuation states to the input signal selectively in accordance with one portion of the produced digital word; and an attenuation section for distributing the plurality of combinations of phase shift-attenuation states over a selected range of attenuations, such range being selected in accordance with a second portion of the produced digital word. The phase shifter-attenuator section provides one of a plurality of combinations of phase shift-attenuation states to the input signal selectively in accordance with one portion of the produced digital word, the combinations being distributed over a range of attentions selected in accordance with a second portion of the digital word.