Multi-Level PAM Transceiver with Integer-Scaled Adaptive Filtering
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Solution Overview
Problem
Existing transceiver circuits face inefficiencies in processing multiple PAM modulation levels due to the need for complex multiplier circuits and increased power consumption when supporting PAM-4, which complicates efficient operation across different PAM levels like PAM-2, PAM-3, and PAM-4 in Ethernet networks.
Innovation Solution
The transceiver circuit employs adaptive filtering with tap weighting blocks and coefficient adaption units that utilize integer scaling factors and avoid multipliers by implementing 3x slicer normalization, using multiplexers and adders to process signals at integer multiples of the normalised digital value Q, reducing hardware complexity and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiplier circuits are used to support PAM-4 modulation, then the transceiver can process higher-order PAM signals, but the hardware complexity and power consumption increase significantly
Solution Approach 1:
The patent changes the numerical parameter of coefficient scaling factors to integer values (1, 2, 3, 4) that are compatible with PAM-2, PAM-3, and PAM-4 modulation levels. This parameter adjustment allows the same hardware structure to support multiple PAM levels without requiring complex multipliers, as integer scaling can be achieved through simpler shift and add operations
Solution Approach 2:
The patent creates a universal adaptive filtering circuit that can handle PAM-2, PAM-3, and PAM-4 modulation levels using the same hardware structure. The tap weighting blocks with integer scaling factors serve multiple PAM modulation functions simultaneously, eliminating the need for separate multiplier circuits for each modulation level and achieving multi-functionality without increased complexity
2Productivity
If multiplier circuits are implemented to enable PAM-4 processing, then higher data rates are achievable, but power consumption increases
Solution Approach 1:
The patent replaces the mechanical/multiplicative operation (multiplier circuits) with simpler arithmetic operations (shift and add circuits). Integer scaling factors allow the use of adders and shift registers instead of power-consuming multipliers, substituting a less energy-intensive computational mechanism while maintaining the capability to process PAM-4 signals at high data rates
3Measurement precision
If complex filtering circuits are used to maintain signal quality across multiple PAM levels, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent changes the coefficient representation to integer scaling factors that maintain signal processing accuracy while simplifying the filtering circuit. The integer-based coefficients (scaling by factors of 1, 2, 3, 4) preserve the precision needed for distinguishing PAM signal levels while allowing implementation through simpler combinatorial logic rather than complex floating-point or fixed-point arithmetic units
Data Source
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AI summary
A transceiver circuit for transmitting and receiving pulse amplitude modulation, PAM, network signals within a network, wherein the PAM network signals can take a value according to a PAM modulation level of any of two-level modulation, three-level modulation or four-level modulation. The transceiver circuit comprises: a receiver-input-terminal for receiving a network signal, an interference cancellation block and an adaptive filtering circuit. The adaptive filtering circuit comprises: a filter-input-terminal; a filter-output-terminal; and a plurality of tap weighting blocks. Each tap weighting block comprises: a tap-input-terminal, a coefficient-input-terminal and a multiplexer. The adaptive filtering circuit also comprises one or more tap summation blocks configured to combine the output of each tap weighting block to provide an interference-error signal to the filter-output-terminal. The interference cancellation block subtracts the interference-error signal from the network signal to provide the processed-network-signal.