TDC-Guided Polar RF Conversion for Low-Power QAM Reception
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Solution Overview
Problem
Conventional wireless radio receivers, particularly those using I/Q transceivers, face challenges with high power consumption and complexity due to the need for high linearity in ADCs to handle signals with large peak-to-average ratios, and polar receivers have been under-studied despite their potential for reduced linearity requirements.
Innovation Solution
A TDC-based hybrid polar data converter and time domain signal processing system that splits the received baseband signal into two branches for phase and amplitude measurement, using TDCs and ADCs to reduce the number of bits required for conversion and power consumption, and integrates a multi-phase-carrier digital transceiver architecture with a broadband digital power amplifier and all-digital phase-locked loop for adaptive reconfiguration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional I/Q transceiver architecture is used, then the receiver can handle signals with large peak-to-average ratios, but the ADC requires high linearity which leads to high power consumption
Solution Approach 1:
The patent segments the signal processing function into two separate converters: a TDC for phase information and an ADC for amplitude information. This segmentation allows each converter to operate with relaxed requirements, reducing overall power consumption while maintaining the ability to handle large peak-to-average ratio signals
Solution Approach 2:
The patent introduces a TDC as an intermediary device between the RF signal and the ADC. The TDC converts the RF signal's phase information into digital form, allowing the ADC to only process amplitude information, thereby reducing the ADC's linearity requirements and power consumption
2Adaptability or versatility
If conventional I/Q transceiver architecture is used, then the receiver can process complex modulations, but the system complexity and ADC bit requirements increase
Solution Approach 1:
The patent segments the complex signal processing task into two simpler sub-tasks: phase measurement by TDC and amplitude measurement by ADC. This segmentation reduces the complexity of each individual component while maintaining the overall capability to process complex modulations
Solution Approach 2:
The patent replaces the conventional ADC-based signal conversion mechanism with a hybrid TDC-ADC approach. The TDC handles the time/phase domain conversion, substituting for part of the ADC's function and reducing the ADC's bit requirements, thereby simplifying the overall system
3Measurement precision
If oversampling is used to improve signal-to-noise ratio, then the measurement precision increases, but the data throughput and processing complexity increase
Solution Approach 1:
The patent extracts the phase information from the RF signal using the TDC before the ADC processes the amplitude information. This extraction allows the ADC to operate at lower sampling rates without oversampling, reducing data throughput requirements while maintaining measurement precision through the TDC's time-domain phase measurement
Data Source
AI summary
The present disclosure includes a time-to-digital converter (TDC) based RF-to-digital (RDC) data converter for time domain signal processing polar receivers. Polar data conversion achieves better SNR tolerance owing to its phase convergence near the origin in a polar coordinate. The proposed RDC consists of a TDC for phase detection and an analog-to-digital converter (ADC) for amplitude conversion. Unlike the conversional data converter, the proposed ADC's sampling position is guided by the detected phase result from the TDC's output. This TDC assisted data-converter architecture reduces the number of bits required for the ADC. In addition, oversampling is no longer needed. With precisely controlled tunable delay cells and gain compensator, this hybrid data convertor is capable to directly convert Quadrature Amplitude Modulation (QAM) waveforms and Amplitude Phase Shift Keying (APSK) waveforms directly from the RF signal without down-conversion. Thus, the proposed RDC architecture achieves lower power consumption and better performance comparing with conventional I/Q receivers.