Multi-Carrier Receiver AGC with Shared Analog and Digital Gain Paths
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Solution Overview
Problem
Conventional multi-carrier wireless receivers face challenges in efficiently managing varying signal strengths across multiple carriers, leading to transient effects and increased cost and power consumption due to the need for independent AGC systems for each carrier.
Innovation Solution
A receiver circuit with a common analog signal path and carrier-specific digital paths, featuring an analog variable-gain circuit before A/D conversion and digital variable-gain circuits after, with a gain control circuit that operates in different modes to allocate gain adjustments based on carrier signal levels and SIR, minimizing the need for multiple independent AGC systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If independent AGC systems are used for each carrier, then signal quality is maintained, but device complexity and power consumption increase
Solution Approach 1:
The AGC system is segmented into a shared analog AGC for common signal path control and carrier-specific digital AGCs for individual carrier adjustment. This segmentation allows the analog portion to serve all carriers efficiently while digital portions handle carrier-specific requirements, reducing overall complexity compared to fully independent systems.
Solution Approach 2:
The patent merges the analog AGC functionality into a single shared component that serves all carriers, eliminating the need for separate analog AGC systems for each carrier. This combining reduces device complexity and power consumption while maintaining signal quality through coordinated digital gain adjustments.
2Reliability
If independent AGC systems are used for each carrier, then signal quality is maintained, but power consumption increases
Solution Approach 1:
The patent combines analog AGC functionality into a single shared resource that serves all carriers simultaneously, dramatically reducing power consumption compared to having separate analog AGC systems for each carrier. Digital AGCs consume less power than their analog counterparts, making this merging strategy particularly effective for power reduction.
Solution Approach 2:
The patent replaces power-hungry analog AGC systems with more efficient digital AGC implementations for carrier-specific adjustments. Digital signal processing consumes less power than analog circuitry, especially when implemented in modern integrated circuits, thereby reducing overall power consumption while maintaining signal quality.
3Reliability
If analog gain adjustments are made frequently, then signal strength variations are corrected, but transient effects and DC offset changes occur
Solution Approach 1:
The patent introduces digital gain adjustment as an intermediary mechanism between the shared analog AGC and the final carrier signals. This digital intermediary allows for fine-tuning of carrier-specific gain without triggering transient effects or DC offset changes that would occur with frequent analog adjustments, thus maintaining signal strength control while eliminating harmful transients.
Solution Approach 2:
The patent substitutes frequent analog gain adjustments with digital gain adjustments for carrier-specific control. Digital gain changes do not produce transient effects or DC offset shifts, unlike analog adjustments. This substitution allows the system to maintain precise signal strength control while avoiding the harmful transient effects associated with analog adjustments.
Data Source
AI summary
Methods and apparatus for providing automatic gain control (AGC) for received multi-carrier signals are disclosed. A receiver circuit comprises a common analog signal path, which includes an analog variable-gain circuit and an analog-to-digital converter, and further comprises first and second carrier-specific, digital variable-gain circuits corresponding to first and second carriers of the received multi-carrier signal, respectively. The receiver circuit further includes a gain control circuit configured to control the analog and digital variable-gain circuits and to allot gain adjustments to the analog variable-gain circuit based on a difference between carrier signal levels for the first and second carriers. In some embodiments, the gain control circuit selectively operates in an all-carrier mode, in which analog gain adjustments are calculated from both of the carrier signal levels, or in an unequal-priority mode, in which analog gain adjustments are calculated from only one of the first and second carrier signal levels.