DTC Predistortion Calibration for Rising and Falling Edge Nonlinearity
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Solution Overview
Problem
Wireless communication devices face challenges with non-linearities in digital-to-time converter (DTC) circuits, leading to increased energy in unwanted harmonics and potential violations of regulatory requirements, particularly in transceiver systems.
Innovation Solution
A DTC calibration circuit is employed to separately capture and compensate for the nonlinearity of rising and falling edges in DTC circuits using loop-back receiver circuits, allowing for pre-distortion of DTC codes to reduce unwanted spurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If DTC circuit is used for phase modulation in transceiver systems, then communication flexibility and bandwidth efficiency are improved, but non-linearities in DTC circuit generate unwanted harmonics that violate regulatory requirements
Solution Approach 1:
The patent applies predistortion to DTC codes before they are used for phase modulation. A calibration process预先 determines the non-linear characteristics of the DTC circuit, and correction codes are generated in advance to compensate for these non-linearities. This preliminary action ensures that the unwanted harmonics are reduced before the signal is transmitted, resolving the contradiction between maintaining communication flexibility and eliminating harmful harmonics.
2Object-generated harmful factors
If traditional calibration methods are used to correct DTC non-linearity, then some harmonic reduction is achieved, but rising and falling edge non-linearities are not separately compensated leading to residual spurs
Solution Approach 1:
The patent segments the DTC non-linearity compensation into separate rising edge and falling edge corrections. The calibration process independently characterizes the non-linearities for rising edges and falling edges, and generates separate predistortion codes for each. This segmentation allows precise compensation for each edge type, eliminating residual spurs that would remain with traditional unified calibration methods.
Solution Approach 2:
The patent applies different predistortion corrections locally to rising edges and falling edges based on their specific non-linear characteristics. Instead of using a single correction for all edges, the system tailors the predistortion codes to match the local non-linearity profile of each edge type, achieving higher precision in non-linearity compensation and further reducing unwanted harmonics.
Data Source
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AI summary
A method for compensating signal nonlinearities includes generating a local oscillator (LO) signal and performing phase modulation of the LO signal to generate a phase-modulated LO signal. The phase modulation is based on applying at least one digital-to-time converter (DTC) code of a plurality of DTC codes to a rising edge signal portion and a falling edge signal portion associated with the LO signal. Nonlinearities associated with the rising edge signal portion and the falling edge signal portion are determined. The at least one DTC code is adjusted based on the nonlinearities.