Dynamic AGC and CFO Preamble Allocation in Receiver Circuits
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Solution Overview
Problem
Communication receiver circuits face challenges in efficiently performing automatic gain control (AGC) and carrier frequency offset (CFO) compensation, particularly in wireless standards like GFSK, where frequency modulation errors lead to signal distortion and reduced receiver sensitivity.
Innovation Solution
A method and apparatus for dynamically allocating portions of a received signal's preamble for AGC and CFO compensation, using an integrated transceiver circuit with an amplifier, analog-to-digital converter, phase detection, and AGC/CFO circuits to adjust gain and correct frequency offset, allowing for rapid and efficient compensation within a limited duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed portion of the preamble is allocated to AGC and CFO correction, then the allocation is simple to implement, but it cannot adapt to varying input power conditions and may result in insufficient correction time
Solution Approach 1:
The patent implements dynamic allocation of preamble portions for AGC and CFO correction based on detected signal characteristics. The receiver determines the input power level and dynamically adjusts the duration allocated to AGC correction versus CFO correction, allowing the system to adapt to varying input power conditions rather than using a fixed allocation scheme.
Solution Approach 2:
The system changes the parameter of preamble allocation duration based on the detected input power level. When input power is high, a shorter AGC portion is allocated; when input power is low, a longer AGC portion is allocated. This parameter adjustment allows optimal use of the limited preamble duration under different operating conditions.
2Measurement precision
If a longer portion of the preamble is allocated to AGC, then AGC correction is more accurate, but less time remains for CFO correction
Solution Approach 1:
The patent dynamically adjusts the split between AGC and CFO correction portions based on the detected input power level. This dynamic allocation ensures that AGC receives sufficient time for accurate correction when needed, while CFO correction also receives adequate time, optimizing the trade-off between the two corrections under different power conditions.
3Loss of time
If a shorter portion of the preamble is allocated to AGC, then more time remains for CFO correction, but AGC correction may be insufficient
Solution Approach 1:
The system changes the allocation parameter based on input power detection. When input power is detected to be high, the system allocates a shorter AGC portion since less gain adjustment is needed. When input power is low, the system allocates a longer AGC portion to ensure sufficient correction time, thereby optimizing the use of preamble duration under different power conditions.
4Measurement precision
If the entire preamble is used for AGC correction, then AGC is highly accurate, but no time remains for data decoding
Solution Approach 1:
The patent applies partial action by allocating only the necessary portion of the preamble to AGC correction based on detected power levels, rather than using the entire preamble for AGC. This allows AGC to receive sufficient correction time while preserving the remaining preamble duration for CFO correction and subsequent data decoding operations.
Data Source
AI summary
In a communication receiver circuit, an amplifier circuit can include an adjustable gain. A signal corresponding to a portion of a transmitted frame can be received, and a gain of the receiver circuit can be adjusted such as automatically, and such adjustment can be referred to as automatic gain control (AGC). An offset correction can be performed to adjust for an error in a received representation of a transmitted carrier, and such offset correction can be referred to as carrier frequency offset (CFO) correction. A portion of the received signal can be dynamically allocated between AGC and CFO correction, such as allocating a longer duration to CFO correction when AGC results in a relatively higher receiver gain, and allocating a shorter duration to CFO correction when AGC results in a relatively lower receiver gain.