Mixed-Mode Receiver Gain Control for Stable RF Power Levels
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Solution Overview
Problem
Existing RF receiver circuits face challenges in maintaining stable signal power levels, leading to undesirable artifacts such as flickering images and volume changes due to sudden power level changes, especially in environments with obstructions, and require a large number of gain elements that increase die size and production costs.
Innovation Solution
A mixed-signal TV receiver circuit with an analog front-end and digital processing unit implementing discrete gain control in both time and amplitude, using CMOS technology to achieve improved noise and distortion performance, lower power consumption, and cost-effectiveness, while allowing programmability across analog and digital TV standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of small gain or attenuation elements are used to achieve desired gain through small gain steps, then gain control precision is improved, but die size and production costs increase
Solution Approach 1:
The gain control is divided into two independent segments: coarse gain control implemented in the analog domain and fine gain control implemented in the digital domain. This segmentation allows each domain to handle the type of control it is best suited for, reducing the total number of gain elements needed while maintaining overall precision.
Solution Approach 2:
The patent replaces purely analog mechanical gain control with a hybrid system that uses digital signal processing for fine gain adjustments. This substitution reduces the need for numerous analog gain elements, thereby reducing die size while maintaining control precision through digital computation.
2Stability of the object's composition
If traditional AGC circuitry is used to adjust gain or attenuation of receiver elements, then power level regulation is improved, but sudden power level changes cause undesirable artifacts such as flickering images and volume changes
Solution Approach 1:
The system performs preliminary detection of signal power levels and prepares gain adjustment decisions before actual gain changes are applied. By detecting power levels and determining required adjustments in advance, the system can smooth transitions and avoid sudden changes that cause visible artifacts like flickering images and volume changes.
Solution Approach 2:
The patent implements feedback mechanisms where the detected signal power level continuously informs gain control decisions. This feedback loop allows the system to monitor power levels and make gradual, controlled adjustments rather than abrupt changes, thereby maintaining stability while avoiding harmful artifacts.
3Device complexity
If highly integrated receivers are used to reduce complexity, then device integration is improved, but the number of gain elements required increases die size and production costs
Solution Approach 1:
The patent merges analog and digital processing domains into a single integrated receiver circuit. The analog front-end handles coarse gain control and signal conditioning, while the digital signal processor handles fine gain control and signal processing. This merging allows the receiver to be highly integrated without requiring a large number of discrete gain elements, as the two domains work together efficiently.
Data Source
AI summary
A receiver circuit includes an analog front-end and a digital processing unit. The analog front-end includes an input for receiving a radio frequency (RF) signal, a first control input for receiving a gain adjustment signal, a second control input for receiving a timing signal, and a signal output for providing a digital intermediate frequency (IF) signal. The analog front-end updates gains of a plurality of gain stages according to the gain adjustment signal and in synchronism with the timing signal. The digital processing unit is configured to produce at least one output signal derived from the digital IF signal. The digital processing unit includes a timing recovery circuit configured to generate the timing signal based on the digital IF signal to control timing of the updating gains of each of the plurality of adjustable gain stages.