Adaptive Equalizer Circuit for Fast ISI Compensation
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Solution Overview
Problem
In wired communication systems, existing semiconductor integrated circuits face challenges in quickly and accurately adapting to intersymbol interference (ISI) due to the long time required for adaptive control of equalizer circuits, which leads to signal distortion and inefficiencies in waveform compensation.
Innovation Solution
A semiconductor integrated circuit that adaptively controls an equalizer circuit and amplifier circuit based on the magnitude relation between differential amplitudes sampled at multiple timings, using a data pattern with a second period where the second data value continues after the first data value, allowing for quick and accurate adjustment of frequency characteristics to compensate for ISI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adaptive control of equalizer circuits is performed using conventional methods, then the equalizer can compensate for intersymbol interference, but the adaptation process requires a long time leading to delayed convergence
Solution Approach 1:
The patent applies preliminary action by using a training sequence transmitted before actual data to pre-adjust the equalizer coefficients. The adaptive control unit performs initial waveform compensation using known training patterns, allowing the system to converge quickly before processing real communication data. This eliminates the need for lengthy adaptation during actual data transmission.
Solution Approach 2:
The patent uses a copied version of the transmitted signal (training sequence) that is known in advance at the receiver. By comparing the received training sequence with the expected original sequence, the system can accurately determine coefficient adjustment directions without the complexity of adapting to unknown data patterns, significantly reducing convergence time.
2Loss of time
If the equalizer circuit is adapted quickly using simplified methods, then the adaptive control time is reduced, but the accuracy of waveform compensation deteriorates
Solution Approach 1:
The patent implements feedback by continuously monitoring the error between the equalized signal and the expected training sequence. The adaptive control unit uses this error feedback to iteratively adjust the equalizer coefficients, ensuring high compensation accuracy. The feedback mechanism allows the system to achieve precise convergence quickly by making targeted coefficient adjustments based on real-time error measurements.
Solution Approach 2:
The patent changes the equalizer coefficients dynamically based on the detected error from the training sequence. By adjusting these parameters (coefficients) in response to measured performance, the system optimizes waveform compensation accuracy. The parameter changes are calculated using the known training sequence properties, enabling both speed and precision.
3Reliability
If complex adaptive control algorithms are used to achieve high compensation accuracy, then waveform compensation improves, but the device complexity and computational load increase
Solution Approach 1:
The patent reduces computational complexity by performing the most intensive adaptive control calculations during the training sequence phase before actual data transmission. Once coefficients are optimized using the known training pattern, the system maintains these settings during data transmission, avoiding continuous complex computations. This separates the computationally heavy adaptation task from the simpler data processing phase.
Solution Approach 2:
The use of a known copied training sequence simplifies the adaptive control algorithm compared to blind adaptation methods. The receiver can directly compare the received training sequence with the expected original sequence, enabling straightforward error calculation and coefficient adjustment without requiring complex blind equalization algorithms, thus reducing device complexity while maintaining accuracy.
Data Source
AI summary
According to one embodiment, in a semiconductor integrated circuit, the second circuit samples an amplitude of the output second signal at a plurality of timings every given cycle in a period corresponding to a second period of the pattern. The second circuit controls a parameter relating to the frequency characteristic for the first circuit according to a first magnitude relation and a second magnitude relation. The first magnitude relation is a relation between an absolute value of a first amplitude and a first threshold. The first amplitude is an amplitude sampled at a first timing among the plurality of timings. The second magnitude relation is a relation between an absolute value of a second amplitude and the first threshold. The second amplitude is an amplitude sampled at a second timing. The second timing is a timing after the first timing among the plurality of timings.