Transmission Line Attenuator Without Series Switches
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Solution Overview
Problem
Ensuring that signals are conveyed along a signal path in electronic devices at desired signal levels is challenging due to variations in process, voltage, and temperature.
Innovation Solution
Incorporating a transmission line-based signal attenuator with adjustable resistances and a controller to mitigate these variations, allowing for impedance matching and signal level adjustments without series switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional series switches are used for signal attenuation, then signal level control is achieved, but insertion loss increases and reliability decreases
Solution Approach 1:
The patent removes series switches from the signal path entirely, extracting the problematic component that causes insertion loss and reliability issues. Instead, it uses shunt resistors connected to ground that can be independently controlled, eliminating the need for series switching elements in the main signal path.
Solution Approach 2:
The patent introduces transmission line segments as intermediary elements between the shunt resistors and signal path. These transmission lines provide impedance transformation and matching, enabling the shunt resistors to control signal attenuation without directly disrupting the main signal flow, thus reducing insertion loss.
2Adaptability or versatility
If adjustable resistances are added for signal level control, then signal attenuation flexibility improves, but device complexity increases
Solution Approach 1:
The patent employs dynamically controllable shunt resistors that can be adjusted independently through control signals. This dynamic control mechanism allows flexible signal attenuation levels to be achieved by varying the resistance values, providing adaptability without requiring complex mechanical or switching structures.
Solution Approach 2:
The patent controls attenuation by adjusting resistance values in the shunt configuration rather than using series switching. This dimensional change from series to shunt control provides a new approach to signal level adjustment that simplifies the overall structure while maintaining flexibility.
3Reliability
If transmission line segment length is optimized for impedance matching, then signal reflection is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses specific transmission line length parameters (quarter-wave, half-wave, or eighth-wave lengths) to achieve impedance matching. By selecting these standardized wavelength-based lengths, the design achieves reliable impedance matching while providing clear manufacturing specifications that balance precision requirements with practical fabrication capabilities.
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 transmission line attenuator effectively maintains signal levels and enhances the flexibility of signal attenuation, reducing insertion loss and increasing the tuning range.
Implementation Method 1
The transmission line segment may have a length configured to perform impedance matching for the attenuator. The length may be one-quarter, one-half, or one-eighth the wavelength
Implementation Method 2
a first adjustable resistance coupled between a first terminal of the transmission line segment and a reference potential, and a second adjustable resistance coupled between a second terminal of the transmission line segment and the reference potential
Data Source
AI summary
An electronic device may include a signal path that conveys a signal. The device may include an attenuator on the signal path that attenuates the signal. The attenuator may be free from series switches on the signal path. The attenuator may include a transmission line segment coupled in series between an input and an output of the attenuator. The transmission line segment may extend from a first terminal to a second terminal. A first adjustable resistance may couple the first terminal to ground. A second adjustable resistance may couple the second terminal to ground. The transmission line segment may have a length configured to perform impedance matching for the attenuator. A controller may control an attenuation level of the signal attenuator by adjusting the magnitude of the adjustable resistances. The controller may include a servo loop around an operational amplifier to mitigate process, voltage, and temperature variations in the attenuator.