Reconfigurable Digital Predistortion Circuit for Signal Integrity
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Solution Overview
Problem
Conventional digital predistortion systems in opto-electronic transmitters fail to effectively compensate for nonlinearity and memory effects introduced by subsequent circuits, leading to degraded signal integrity and interoperability issues across different transmitter models and varying environmental conditions.
Innovation Solution
A reconfigurable digital predistortion circuit with dynamically configurable delay elements and lookup tables, coupled with a cross-terms generation circuit, which adjusts coefficients and weights based on temperature and voltage variations to maintain signal linearity and frequency flatness, ensuring compliance with industry standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional digital predistortion systems are used, then the system structure is simple, but signal integrity is degraded due to inability to compensate for nonlinearity and memory effects
Solution Approach 1:
The patent implements a reconfigurable predistortion circuit where delay element values and filter tap coefficients can be dynamically adjusted based on operating conditions such as temperature and voltage. This dynamic adaptation allows the system to maintain signal integrity across varying environmental conditions while managing circuit complexity through structured reconfiguration capabilities.
Solution Approach 2:
The system changes physical parameters including delay values, filter coefficients, and cross-term weights to compensate for nonlinearity and memory effects. By adjusting these parameters based on measured performance degradation, the system maintains signal integrity without requiring a complete redesign of the circuit architecture.
2Adaptability or versatility
If fixed predistortion coefficients are used, then the circuit is simple, but adaptability to environmental variations is poor
Solution Approach 1:
The patent incorporates feedback mechanisms that monitor signal quality and environmental conditions, then adjust predistortion coefficients accordingly. This closed-loop approach enables the system to adapt to temperature and voltage variations automatically, maintaining interoperability across different transmitter models while managing configuration complexity through systematic feedback control.
Solution Approach 2:
The reconfigurable predistortion circuit is designed to work across multiple transmitter models and environmental conditions through a unified architecture. By implementing universal delay elements, filter taps, and cross-term generation that can be configured for different scenarios, the system achieves broad adaptability without requiring model-specific hardware designs.
3Measurement precision
If more delay elements and filter taps are added, then compensation accuracy is improved, but power consumption increases
Solution Approach 1:
The patent implements a selective activation strategy where not all delay elements and filter taps are activated simultaneously. Based on the specific operating conditions and required compensation accuracy, the system activates only the necessary subset of predistortion components, achieving adequate compensation while reducing power consumption compared to using all available elements.
Data Source
AI summary
A system comprises a digital predistortion circuit comprising: a first quantity of delay circuits configured to delay a signal to be predistorted; a second quantity of filter tap circuits, wherein the second quantity is smaller than the first quantity; and a delay-to-filter-taps mapping circuit that is operable to map each output of a first subset of the delay circuits to a corresponding input of the filter tap circuits. The system may comprise circuitry operable to select which of the first quantity of delay circuits is in the first subset. The selection of which of the first quantity of delay circuits is in the first subset may be based on a temperature measurement. The digital predistortion circuit may comprise cross-term generation circuitry operable to generate cross-term signals corresponding to the cross products of multiple, differently-delayed versions of a signal input to the digital predistortion circuit.