RF-to-Digital Receiver Using Multirate Bandpass Down-Conversion
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Solution Overview
Problem
Existing radio frequency (RF) to digital receiver architectures face challenges with high power consumption and design complexity due to stringent requirements on analog-to-digital converters (ADCs) and the need for high-speed clock rates, which can degrade signal-to-noise ratio (SNR) and limit voltage headroom as process technology advances.
Innovation Solution
A low power RF to digital receiver employing multirate digital signal processing (MDSP) and a bandpass continuous time delta sigma analog-to-digital converter (BP-CT-ΔΣ-ADC) for efficient bandpass filtering and down-conversion, allowing sampling at a rate less than the Nyquist rate of the RF carrier frequency, reducing power consumption and complexity by processing signals at the signal bandwidth rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-speed sampling is used to meet Nyquist rate requirements, then signal fidelity is maintained, but power consumption and design complexity increase significantly
Solution Approach 1:
The patent segments the high-rate sampling process into multiple lower-rate sampling stages interspersed with digital filtering operations. Instead of sampling at the full Nyquist rate continuously, the system performs intermittent sampling at lower rates between filtering operations, thereby reducing overall power consumption while maintaining signal fidelity through the combined effect of multiple sampling instances and digital reconstruction filtering.
2Measurement precision
If synchronous sampling clock is used at high frequency, then signal accuracy is maintained, but overhead of design complexity and power consumption increases
Solution Approach 1:
The patent implements dynamic sampling rate adjustment where the sampling clock frequency is varied based on the current processing stage and signal characteristics. Rather than using a fixed high-frequency synchronous clock throughout, the system dynamically selects appropriate sampling rates for different operational phases, reducing clock frequency and associated complexity overhead when full sampling rate is not required for signal accuracy.
3Use of energy by moving object
If under sampling strategy is adopted to reduce power consumption, then power overhead decreases, but extra noise is folded into baseband degrading SNR
Solution Approach 1:
The patent introduces digital filtering as an intermediary process between sampling stages. This digital filter acts as a mediator that removes the noise components folded into the baseband during under-sampling, thereby preserving signal-to-noise ratio while allowing the system to operate at reduced sampling rates and lower power consumption. The filter cleans up the spectral images and aliasing noise that would otherwise degrade the signal.
4Productivity
If process technology advances with decreasing supply voltage, then integration density increases, but voltage headroom becomes limited
Solution Approach 1:
The patent replaces analog signal processing mechanisms with digital signal processing operations. By moving filtering, frequency conversion, and other signal conditioning functions into the digital domain, the system reduces reliance on analog circuits that require significant voltage headroom for proper operation. This substitution enables the receiver to function correctly even with the reduced supply voltages characteristic of advanced process technologies, thereby maintaining integration density benefits without suffering from voltage headroom limitations.
Data Source
AI summary
A radio frequency to digital receiver has a modulator sampling a signal at a first rate. The receiver has at least one processing unit. The processing unit has a plurality of digital bandpass filters separating the signal and recombining the signal at a rate less than the first rate. The processing unit has a digital down converter adjusting frequency offset or centering the signal at the rate less than the first rate. The receiver has at least one rate control buffer coupled to adjacent processing units when two or more processing units are within the receiver.