Digital AGC Resampling for Low-Signal RF Receivers
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Solution Overview
Problem
Current RF receivers rely on analog components for automatic gain control, which limits their ability to efficiently process low signal strengths and increases costs, especially in devices like GNSS receivers where signal levels are often below noise levels.
Innovation Solution
A digital automatic gain control system is implemented using a logarithmic analog-to-digital converter, a FIR filter, a resampler, and an automatic gain control circuit that controls the resampling process to provide gain control in the digital domain, reducing the bit count of the signal and improving processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If analog automatic gain control circuitry is used in RF receivers, then the receiver can maintain dynamic range control, but the receiver cannot efficiently process low signal strengths and incurs higher costs
Solution Approach 1:
The patent replaces the analog automatic gain control circuit with a digital AGC system that operates in the digital domain after the analog-to-digital converter. The digital signal processor implements gain control algorithms digitally, substituting analog circuitry with digital processing to achieve better performance in processing low signal strengths while reducing manufacturing costs through integration.
2Power
If analog automatic gain control circuitry is used in RF receivers, then the receiver can maintain dynamic range control, but the receiver consumes more power and has reduced processing power
Solution Approach 1:
The patent substitutes analog gain control circuitry with digital signal processing operations performed by a digital signal processor. This enables the system to leverage the higher processing power of digital systems while achieving lower power consumption through efficient digital algorithms and integration, eliminating the need for separate analog control circuits.
3Adaptability or versatility
If all receiver components are digital, then the receiver achieves lower cost and improved performance, but certain components must still operate in the analog domain
Solution Approach 1:
The patent extracts the automatic gain control function from the analog domain and relocates it to the digital domain, separating this specific function from the remaining analog components. This allows the majority of the receiver to operate digitally while only the necessary front-end components (LNA, mixer, ADC) remain analog, reducing overall system complexity and enabling better integration.
4Ease of manufacture
If digital circuitry is used in all subcomponents, then the receiver can be formed on a single substrate, but analog components are still required for certain functions
Solution Approach 1:
The patent replaces the analog automatic gain control circuit with a digital implementation, allowing this function to be integrated into the digital signal processor on the same substrate. This substitution enables single-substrate integration while maintaining the necessary signal processing capabilities, as the digital AGC can accurately control gain without requiring separate analog circuitry.
Data Source
AI summary
A method and apparatus for providing a digital automatic gain control (AGC) for a radio-frequency (RF) receiver. The receiver comprises a logarithmic analog-to-digital converter for sampling the analog RF signals, a FIR filter for filtering the digitized signals, a resampler for resampling the digitized signals, and an automatic gain control circuit. The AGC circuit controls the resampling process to provide automatic gain control function in the digital domain. The resampler circuit has as its input a digital signal having a first plurality of bits. The output signal from the resampler has a second plurality of bits, where the second plurality of bits are less than the first plurality of bits. The automatic gain control circuit controls the resampling of the first plurality of bits to form the second plurality of bits in accordance with an automatic gain control signal.