OFDM Receiver Multiple Demodulation Paths Oversampling ADC

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Solution Overview

Problem

Conventional OFDM receiving circuits face challenges in increasing the oversampling ratio (OSR) without significantly raising the sampling frequency, which limits the performance improvement of oversampling ADCs due to increased aperture errors and clock jitter.

Innovation Solution

The implementation of multiple demodulation paths in the OFDM receiving circuit, where the OFDM signal is divided into several bands, each processed by a separate demodulation path, including both oversampling and nyquist rate ADCs, to enhance digital filtering and demodulation, thereby increasing the OSR without excessive sampling frequency increases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the sampling frequency is increased to increase the oversampling ratio, then the ADC performance is improved, but the aperture error and clock jitter error increase

Engineering Contradiction:

ImproveADC performanceVSAvoidaperture error and clock jitter error

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent divides the OFDM signal band into multiple frequency bands and processes each band through separate demodulation paths with individual ADCs. This segmentation allows each ADC to operate at a lower sampling frequency tailored to its specific band, thereby reducing aperture error and clock jitter error while maintaining overall ADC performance improvement through oversampling.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the sampling frequency parameter for each demodulation path according to the specific bandwidth requirements of each frequency band. By optimizing the sampling frequency for each path rather than using a uniform high sampling frequency for the entire band, the system achieves better ADC performance without proportionally increasing aperture and clock jitter errors.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the oversampling ratio is increased to improve SNR, then the ADC performance is improved, but the sampling frequency must increase proportionally which is limited by aperture error and clock jitter

Engineering Contradiction:

ImproveSNRVSAvoidsampling frequency requirement

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the overall demodulation process into multiple parallel paths, each handling a specific frequency band. This allows the system to achieve high SNR through oversampling in each path while using lower individual sampling frequencies, avoiding the need for a single high sampling frequency that would increase device complexity and error rates.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent transitions from a single-dimensional sampling approach (one sampling frequency for the entire band) to a multi-dimensional approach where different sampling frequencies are applied to different frequency bands. This dimensional change allows independent optimization of each path's sampling parameters to achieve high SNR without uniform high sampling frequency requirements.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS8243579B2OFDM receiving circuit having multiple demodulation paths using oversampling analog-to-digital converter

Publication Date: 2012.08.14 GCT SEMICONDUCTOR INC

AI summary

Embodiments according to the application relates to an OFDM (orthogonal frequency division multiplexing) receiving circuit and methods thereof configured to have a plurality of demodulation paths for an oversampling ADC, which can increase or improve an overall performance of the circuit.