Differential Attenuation Circuit With Switch-Free Signal Paths
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Solution Overview
Problem
Differential attenuation circuitry in analogue-to-digital converters faces challenges in maintaining accurate operation at increasing speeds and miniaturization, particularly due to non-linearity introduced by switches and the need for input impedance matching.
Innovation Solution
The implementation of differential attenuation circuitry with an impedance network and switch paths that provide independent current paths, avoiding the common-mode node, and utilizing impedance networks like L, T, or π configurations, along with common-mode setting circuitry and ESD protection, to adjust attenuation and ensure input impedance matching while minimizing non-linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If switches are used to adjust attenuation in the impedance network, then attenuation adjustability is improved, but non-linearity is introduced into the differential output voltage signal
Solution Approach 1:
The patent extracts the harmful effect by separating the switch non-linearity from the differential signal path. Switches are placed only in common-mode current paths, while differential-mode current paths remain switch-free, thereby extracting the non-linearity problem from the critical signal path and confining it to non-critical common-mode paths.
Solution Approach 2:
The patent applies different structural qualities to different parts of the circuit: the differential-mode path uses high-linearity components (resistors, capacitors, inductors) without switches, while the common-mode path uses switches for attenuation control. This local differentiation of quality allows attenuation adjustability where needed while preserving linearity where critical.
2Adaptability or versatility
If attenuation is adjusted using conventional impedance networks, then attenuation level changes, but input impedance matching deteriorates
Solution Approach 1:
The patent segments the impedance network into independent differential-mode and common-mode current paths with separate attenuation control mechanisms. The differential-mode path uses fixed impedance components for stable input matching, while the common-mode path provides attenuation adjustment, allowing independent optimization of both functions without mutual interference.
Solution Approach 2:
The patent implements dynamic attenuation adjustment through switches in the common-mode path that can be controlled independently of the differential-mode signal. This allows the attenuation level to be dynamically changed while the differential input impedance remains statically matched through the fixed differential-mode impedance network.
3Productivity
If circuitry is miniaturized for increasing speeds, then integration density is improved, but operational accuracy deteriorates
Solution Approach 1:
The patent replaces mechanical/physical constraints with electrical field-based solutions by using electromagnetic coupling and impedance transformation to achieve attenuation without physical switches in the critical signal path. This substitution allows miniaturization while maintaining accuracy through field-based control mechanisms.
Data Source
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AI summary
Differential attenuation circuitry, comprising: first and second input nodes; first and second output nodes; and an impedance network connected between the first and second input nodes and the first and second output nodes to provide a differential output voltage signal between the first and second output nodes which is attenuated compared to a differential input voltage signal applied between the first and second input nodes, wherein the impedance network comprises: a common-mode node; a first impedance network connected between the first input node, the common-mode node and the first output node; and a second impedance network connected between the second input node, the common-mode node and the second output node, and wherein the differential attenuation circuitry further comprises: an input-to-input path comprising one or more impedances and one or more switches connected between the first and second input nodes to provide a current path independent of the common-mode node between the first and second input nodes when the one or more switches of that path are ON; and/or an output-to-output path comprising one or more impedances and one or more switches connected between the first and second output nodes to provide a current path independent of the common-mode node between the first and second output nodes when the one or more switches of that path are ON.