Digital Step Attenuator Circuit for Fast Transient Settling
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Solution Overview
Problem
Digital step attenuators (DSAs) in RF receivers face slow transient settling due to high effective resistance, leading to erroneous output signals and unsuitability for wideband and multiband applications.
Innovation Solution
Incorporating a time-dependent resistor in the DSA, which varies its resistance with time, either linearly, exponentially, or as a function of time, to reduce the effective resistance and facilitate faster discharge of abrupt charges, thereby improving transient settling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If large effective resistance is used in DSA, then noise figure is improved, but transient settling time increases
Solution Approach 1:
The patent applies a time-dependent resistor whose resistance value dynamically changes over time. During the transient phase after attenuation modification, the resistor provides low resistance to enable fast discharge of abrupt charges. As time progresses, the resistance increases to reach a steady-state value that maintains good noise figure performance. This dynamic adjustment resolves the contradiction between fast settling and low noise.
Solution Approach 2:
The patent changes the resistance parameter of the resistor from a static value to a time-varying value. The resistance transitions from a low initial value (enabling fast transient response) to a high steady-state value (ensuring good noise figure). This parameter change strategy allows the system to optimize both transient settling time and noise performance at different time intervals.
2Adaptability or versatility
If DSA supports large range of attenuations, then dynamic range is improved, but transient settling performance deteriorates
Solution Approach 1:
The time-dependent resistor dynamically adjusts its resistance based on the attenuation setting. When large attenuation values are selected, the resistor provides appropriately timed discharge paths that maintain fast settling performance regardless of the attenuation range. This ensures that the DSA can support wide dynamic range while maintaining consistent transient settling characteristics across all attenuation levels.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The time-dependent resistor significantly reduces the settling time of abrupt charges, making the DSA more suitable for wideband and multiband applications by ensuring faster and accurate signal processing.
Implementation Method 1
a time dependent resistor coupled to a source voltage and to the sampling capacitor
Data Source
AI summary
The disclosure provides an RF receiver. The RF receiver includes an input driver. The input driver receives a coarse signal, and generates an input signal. A digital step attenuator (DSA) is coupled to the input driver and receives the input signal. An analog to digital converter (ADC) is coupled to the DSA. The DSA includes a sampling capacitor coupled to the ADC. The DSA also includes a time dependent resistor coupled to a source voltage and to the sampling capacitor.