Piecewise Linear Phase Interpolator for Phase and Amplitude Uniformity
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Solution Overview
Problem
Phase interpolators often produce output signals with varying amplitudes and non-linear phase distribution due to the use of constant relative gains across the entire phase range, leading to integral and differential non-linearity issues.
Innovation Solution
Selecting different relative gains for each reference signal and dividing the phase range into sections and subsections, with independent delta currents for each subsection to control the output signals, allowing for finer phase control and approximation of ideal phase distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If constant relative gains are used across the entire phase range, then the device complexity is reduced, but the phase linearity and uniformity deteriorate
Solution Approach 1:
The phase range is divided into multiple sections, with each section having its own set of delta currents. This segmentation allows independent optimization of phase linearity in each section while managing overall device complexity through modular structure.
Solution Approach 2:
Different delta currents are assigned to different sections of the phase range, allowing each section to have locally optimized characteristics. This enables precise control of phase linearity in each region while maintaining manageable device complexity through localized adjustments.
2Device complexity
If constant relative gains are used across the entire phase range, then the device complexity is reduced, but the amplitude uniformity deteriorates
Solution Approach 1:
The phase range is segmented into multiple sections, each with independently optimized delta currents. This allows amplitude uniformity to be improved in each section without requiring complete redesign of the entire system, balancing complexity and precision.
Solution Approach 2:
Each section has locally optimized delta currents that compensate for amplitude variations specific to that region. This local quality approach improves overall amplitude uniformity while keeping device complexity manageable through localized rather than global adjustments.
3Measurement precision
If more delta currents are used for each section, then the phase interpolation precision is improved, but the device complexity increases
Solution Approach 1:
The phase range is divided into multiple sections, distributing the precision requirements across segments. This allows high phase interpolation precision to be achieved in each section with a manageable number of delta currents, avoiding the need for excessive currents across the entire range.
Solution Approach 2:
Each section uses a focused set of delta currents optimized for its specific phase range, providing sufficient precision for that section without the excess complexity of using maximum currents across all sections. This partial action approach achieves required precision with reduced overall complexity.
Data Source
AI summary
In one embodiment, a phase interpolator with a phase range of n degrees, where 0<n≦360, and having m reference signals, where m≧2, and a control signal as input, and producing an output signal with a phase within the phase range using one or more of the m reference signals based on a control code provided by the control signal. The phase interpolator comprises one or more circuits configured to: divide the phase range of n degrees into k sections, wherein k>m; and for each of the k sections, select a relative gain of one or more weights assigned to the one or more reference signals, respectively, with respect to the control code provided by the control signal.