Differential DA Converter Noise Reduction With Buffer Discharge
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Solution Overview
Problem
Conventional Digital-to-Analog (DA) converters generate switching noise due to the use of switches, which can distort analog signals.
Innovation Solution
A DA converter design that includes a current output unit for both wires, a converting unit for differential analog signal output, and noise reducing units with switches and buffers or capacitors to manage noise, ensuring even distribution and cancellation of noise components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a switch is used to switch current value in the current output circuit, then the current value can be changed according to the digital signal, but switching noise is generated and analog signals are distorted
Solution Approach 1:
The patent introduces a capacitor as an intermediary element between the switch and the converting circuit. This capacitor acts as a buffer that absorbs the switching noise generated by the switch, preventing it from reaching the converting circuit and distorting the analog signal. The capacitor mediates between the digital switching action and the analog conversion process, allowing current value switching while filtering out the harmful noise components.
2Ease of operation
If a switch is used to switch current value, then digital signal control is achieved, but the analog output signal quality deteriorates due to noise
Solution Approach 1:
The capacitor serves as a mediating element that preserves the ease of digital control through the switch while protecting the analog signal quality. It absorbs the high-frequency switching noise generated during digital control operations, allowing the system to maintain simple digital control capability without sacrificing analog output precision.
Solution Approach 2:
The capacitor is positioned in advance between the switch and the converting circuit to cushion against upcoming switching noise. This prior cushioning arrangement ensures that when the switch operates to change current values according to digital signals, the noise is already buffered by the capacitor before it can affect the analog signal quality.
3Object-generated harmful factors
If noise reducing units with switches and buffers are added, then switching noise is reduced, but device complexity increases
Solution Approach 1:
The patent employs a simple capacitor as an intermediary noise-reducing element rather than complex active noise cancellation circuits. This passive capacitor provides effective noise reduction by filtering switching noise while adding minimal complexity to the overall circuit structure. The simplicity of the capacitor-based approach contrasts with more complex active filtering or noise cancellation schemes.
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 solution effectively reduces switching noise and prevents distortion in output analog signals by managing noise components through strategic switching and buffering/capacitive discharge, even with non-ideal circuit configurations.
Implementation Method 1
a second noise reducing unit that is electrically connected with the second wire, and discharges electric charges corresponding to a noise component generated at the current output unit
Data Source
AI summary
To reduce distortion of output analog signals generated at a current-output DA converter. A DA converter that outputs a differential analog signal corresponding to an input digital signal is provided, including: a current output unit outputting a current corresponding to the digital signal to each of first and second wires; a converting unit outputting, as positive-side and negative-side analog signals, voltage signals based on currents flowing through the first and second wires, respectively; a first noise reducing unit having: a first switch switched to be or not to be electrically connected with the first wire; and a first buffer provided between the first switch and a reference potential; and a second noise reducing unit having: a second switch switched to be or not to be electrically connected with the second wire; and a second buffer provided between the second switch and the reference potential.