Automatic Gain Control with Frequency-Response Simulation
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Solution Overview
Problem
In high-speed communication systems like LTE, the cumulative delay between gain control devices and gain controlled elements in receiving circuits leads to slow Automatic Gain Control (AGC) response times, resulting in data loss and degraded Quality of Service (QoS) due to prolonged glitch durations and frequent signal variance.
Innovation Solution
An automatic gain control apparatus with a simulator that simulates the frequency response of power elements between gain controlled elements, allowing gain control devices to derive input signals before they pass through all elements, thereby eliminating undesirable time delays and improving AGC response speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gain control devices are arranged to derive signals after passing through all gain controlled elements and power elements, then comprehensive gain control is achieved, but cumulative delay increases and AGC response speed decreases
Solution Approach 1:
The patent applies preliminary action by deriving the gain control signal from the input signal before it passes through the gain controlled elements and power elements. The gain control device processes the input signal directly to generate the gain control signal, eliminating the need to wait for the signal to traverse the entire signal path. This preliminary derivation of the control signal resolves the contradiction by achieving fast AGC response without compromising comprehensive gain control, as the control signal is generated in advance based on the input signal characteristics.
2Reliability
If multiple power elements are arranged between gain control device and gain controlled element, then complete signal processing is achieved, but cumulative delay increases and data loss occurs
Solution Approach 1:
The patent applies preliminary action by generating the gain control signal before the input signal passes through the power elements. The gain control device derives the control signal from the input signal immediately, without waiting for the signal to traverse the power elements. This eliminates the cumulative delay caused by multiple power elements while maintaining complete signal processing, as the control signal is prepared in advance based on the input signal characteristics.
3Reliability
If AGC response time is longer than 500ns in LTE systems, then filtering and processing are thorough, but over 15 samples data are lost and QoS deteriorates
Solution Approach 1:
The patent applies preliminary action by deriving the gain control signal from the input signal before it passes through the gain controlled elements and power elements. The gain control device processes the input signal directly to generate the gain control signal, eliminating the need to wait for the signal to traverse the entire signal path. This preliminary derivation of the control signal resolves the contradiction by achieving fast AGC response without compromising comprehensive gain control, as the control signal is generated in advance based on the input signal characteristics.
Data Source
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AI summary
The embodiments disclose a method and apparatus for automatic gain control. The apparatus comprises a first gain controlled element, a second gain controlled element, a first gain control device, a second gain control device and a first simulator. The first gain controlled element and the second gain controlled element each has a signal input, a gain control input and a signal output. The first gain controlled element and the second gain controlled element are coupled in series and one or more power elements coupled between the first gain controlled element and the second gain controlled element. The signal input of the first gain controlled element constitutes an input of the automatic gain control apparatus. The first gain control device has a pre-detection input which is coupled to the signal input of the first gain controlled element and an output which drives the gain control input of the first gain controlled element. The second gain control device has a pre-detection input and an output which drives the gain control input of the second gain controlled element. The first simulator is coupled between the signal input of the first gain controlled element and the pre-detection input of the second gain control device, which is used to simulate frequency response of the one or more power elements between the first gain controlled element and the second gain controlled element, such that a signal received by the pre-detection input of the second gain control device is matched with a signal received by the signal input of the second gain controlled element.