Joint DSA-VVA Gain Control for Step Attenuation Spike Compensation
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Solution Overview
Problem
Existing receiver systems face challenges in handling a wide dynamic range of signal strengths without causing distortion or incurring high costs, especially when using variable voltage attenuators (VVAs) which can introduce limitations such as limited frequency bandwidth and high distortion.
Innovation Solution
The implementation of a method that coordinates the control of digital step attenuators (DSAs) and VVAs to compensate for gain control output spikes, ensuring smooth gain control across a wide dynamic range without discontinuities, thereby preventing power spikes and maintaining signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a variable voltage attenuator (VVA) is used to handle a wide dynamic range of signals, then the receiver can process signals from -40 dBm to 30 dBm, but the VVA introduces distortion especially at the margins of the dynamic range and may have limited frequency bandwidth
Solution Approach 1:
The patent divides the single VVA into two separate attenuators: a digital step attenuator (DSA) that handles coarse attenuation in fixed steps, and a remaining VVA that handles fine continuous attenuation. This segmentation allows the DSA to provide most of the dynamic range adjustment while the smaller-range VVA operates within its linear region, reducing distortion and improving frequency response.
2Object-affected harmful factors
If a VVA with low distortion across the dynamic range is implemented, then signal quality improves, but the cost increases and/or the frequency bandwidth is limited
Solution Approach 1:
The patent segments the attenuation function between a DSA (handling coarse steps) and a VVA (handling fine continuous adjustment). This allows using a lower-cost, smaller-range VVA that operates within its optimal linear region, reducing distortion without requiring an expensive high-range VVA with limited bandwidth.
Solution Approach 2:
The DSA acts as an intermediary that pre-adjusts the signal level before it reaches the VVA. By handling the coarse attenuation steps, the DSA allows the VVA to operate within a smaller, optimized range where it can provide smooth continuous control with minimal distortion and better frequency response.
3Adaptability or versatility
If the DSA changes attenuation in discrete steps, then it can handle wide dynamic range adjustments, but output spikes occur when the DSA steps change
Solution Approach 1:
The VVA acts as an intermediary that smooths the transitions caused by DSA steps. When the DSA changes attenuation in discrete steps, the VVA continuously adjusts to fill in the gaps and eliminate output spikes, ensuring smooth gain control across the entire dynamic range without discontinuities.
Solution Approach 2:
The patent ensures continuous attenuation control by combining the stepped DSA with the continuous VVA. The VVA continuously adjusts to compensate for DSA step changes, maintaining uninterrupted and smooth signal attenuation without spikes or discontinuities throughout the dynamic range.
Data Source
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AI summary
Signal processing to compensate for gain control output spikes caused by steps in a digital step attenuator. A method includes receiving a changing power input signal at a receiver. The method includes determining that a change in power of the input signal will cause a step attenuator to change its attenuation in a step of a predetermined amount. The method further includes based on determining that the change in power of the input signal will cause a digital step attenuator to change its attenuation in a step of a predetermined amount, causing a variable attenuator to change its attenuation by an amount related to the predetermined amount at a time coinciding with a time when the step attenuator changes its attenuation by the predetermined amount. The method further includes outputting a gain-controlled output signal resulting from applying the step attenuator and the variable attenuator to the changing power input signal.