NFC Receiver Direct Sampling ADC Phase Diversity
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Solution Overview
Problem
Existing NFC receivers are complex and costly due to the use of multiple analog circuits for synchronous reception, making it difficult to design and manage them, and they often attenuate received AM signals with peaks outside the ADC input range, leading to information reception errors.
Innovation Solution
A near-field communication (NFC) receiver design that minimizes the number of analog circuits by using direct sampling with ADCs, where the ADCs sample the AM signal based on clock signals with phase differences of 45° and 135° from a reference clock, allowing for the detection of an envelope without attenuating AM signals with peaks outside the ADC input range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple analog circuits are used for synchronous reception, then reception performance is improved, but device complexity increases
Solution Approach 1:
The patent replaces the traditional synchronous reception method using multiple analog circuits with a direct sampling method using ADCs. Instead of using analog mixers, local oscillators, and phase synchronization circuits, the invention directly samples the AM signal in the time domain using ADCs with clock signals having different phase relationships (0° and 90°), converting the analog signal to digital form for processing. This substitution of analog circuitry with digital sampling techniques resolves the contradiction by maintaining reception performance while dramatically reducing device complexity.
Solution Approach 2:
The patent changes the sampling approach by using ADCs with different clock phase parameters (0° and 90° phase difference) to capture the AM signal at different points in its cycle. By sampling at multiple phases and combining the results, the system can reconstruct the envelope information without requiring complex analog synchronization circuits. This parameter change in the sampling strategy enables performance maintenance with reduced circuit complexity.
2Ease of manufacture
If ADC input range is limited, then manufacturing cost is reduced, but information reception accuracy deteriorates
Solution Approach 1:
The patent segments the sampling process into multiple channels, each using ADCs with limited input ranges. By using two ADCs with clock signals at different phases (0° and 90°), the system divides the sampling task across multiple lower-range ADCs rather than requiring a single high-range ADC. The segmented sampling results are then combined through digital processing to reconstruct the full envelope information, maintaining accuracy while using cheaper, lower-range ADCs.
Solution Approach 2:
The patent adds a temporal dimension to the sampling process by introducing phase diversity. Instead of relying on a single ADC measuring the full signal range, the system samples at different time points (phases) and combines the measurements. This dimensional approach to sampling allows reconstruction of the complete signal envelope using multiple limited-range ADCs, effectively trading temporal processing for reduced hardware requirements and cost.
Data Source
AI summary
Provided is a near-field communication (NFC) receiver. The NFC receiver includes at least one antenna configured to receive an amplitude modulation (AM) signal, a first analog-to-digital converter (ADC) configured to generate an in-phase (I)-sample by sampling the AM signal based on a first clock signal, a second ADC configured to generate a quadrature-phase (Q)-sample by sampling the AM signal based on a second clock signal, the second clock signal having a phase difference of 90° from the first clock signal, and processing circuitry configured to calculate a root-sum-square (RSS) value between the I-sample and the Q-sample, and detect an envelope of the AM signal by using the RSS value.