Hybrid AGC Attenuator With Quantization Error Compensation
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Solution Overview
Problem
Existing semiconductor devices for automatic gain control (AGC) face challenges in achieving low power consumption, small footprint, and good linearity over a full dynamic range, leading to issues such as sudden reception signal power changes and noise in broadcast signal reception.
Innovation Solution
A semiconductor device incorporating an input attenuator with a step function, an analogue to digital converter, and a digital attenuator that compensates for quantization errors, using a control signal and step compensation signal to provide precise AGC, with components that can be scaled for low power consumption and high dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a conventional AGC circuit is used, then the device can control signal gain, but it consumes high power and occupies large area
Solution Approach 1:
The AGC function is segmented into two independent parts: a coarse attenuation stage using a step attenuator and a fine attenuation stage using a variable gain amplifier. This segmentation allows each part to be optimized separately, with the step attenuator handling large signal variations efficiently and the VGA handling precise adjustments, thereby reducing overall power consumption while maintaining AGC reliability
Solution Approach 2:
The invention transitions from a single-dimension continuous analog AGC approach to a two-dimension hybrid approach combining discrete step attenuation with continuous variable gain control. This dimensional change enables the system to achieve both coarse and fine control levels, improving power efficiency by operating the VGA only in its optimal low-power range while the step attenuator handles the bulk of attenuation requirements
2Area of stationary object
If a conventional AGC circuit is used, then the device can control signal gain, but it occupies large footprint area
Solution Approach 1:
By segmenting the attenuation function into discrete step levels (handled by the step attenuator) and continuous fine adjustment (handled by the VGA), the design reduces the overall circuit complexity and component count required for a conventional single-stage AGC, thereby reducing footprint area while preserving full AGC functionality
Solution Approach 2:
The invention extracts the coarse attenuation function from the main AGC path and places it in a separate step attenuator stage. This extraction allows the main VGA to operate in a more efficient, lower-power, and smaller-area mode since it only needs to handle fine adjustments rather than the full dynamic range, reducing the overall footprint
3Use of energy by stationary object
If a step attenuator is used for AGC, then power consumption is reduced, but quantization error causes signal quality degradation
Solution Approach 1:
The variable gain amplifier acts as an intermediary between the step attenuator and the tuner input, compensating for the quantization errors introduced by the step attenuator. The VGA provides continuous fine-adjustment capability that smooths out the discrete steps, thereby maintaining signal precision while allowing the power-efficient step attenuator to handle the bulk of the attenuation
Solution Approach 2:
The system employs feedback control where the output signal level is monitored and used to adjust both the step attenuator and VGA settings. This feedback mechanism ensures that quantization errors from the step attenuator are compensated by corresponding adjustments in the VGA, maintaining precise signal control while benefiting from the power efficiency of the stepped approach
4Object-affected harmful factors
If aggressive attenuation is applied to reduce noise, then noise is reduced, but linearity deteriorates over full dynamic range
Solution Approach 1:
The attenuation function is segmented into coarse steps and fine adjustments, allowing the system to apply attenuation in a controlled, progressive manner rather than aggressively. This segmentation maintains linearity by ensuring that each stage operates within its optimal linear range, while still achieving effective noise reduction through the combined attenuation of both stages
Solution Approach 2:
The invention changes the attenuation parameter application method from a single aggressive adjustment to a two-stage process with different attenuation ranges. The step attenuator provides large-step parameter changes for coarse control, while the VGA provides small-step parameter changes for fine control, maintaining overall linearity across the full dynamic range while effectively reducing noise
Data Source
AI summary
A semiconductor device is provided, including an input attenuator configured to receive an antenna signal and to output a first attenuated signal, the first attenuated signal corresponding to the antenna signal attenuated by a first attenuation factor, the input attenuator being further configured to receive a control signal and to select one of a plurality of predetermined attenuation factors as said first attenuation factor depending on the control signal; an analog to digital converter configured to generate an intermediate signal by digitizing the first attenuated signal; and a digital attenuator configured to receive the intermediate signal and to output a second attenuated signal, the second attenuated signal corresponding to the intermediate signal attenuated by a second attenuation factor, the second attenuation factor being set so as to compensate a gain quantization error of the control signal.