Current-Mirror DAC Circuit for Flexible Output Drive
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing digital-analog converters have limited current drive capability due to the use of resistor ladders, which restricts the degree of freedom in current supply at the output, necessitating an improvement in this aspect.
Innovation Solution
A digital-analog converter circuit that includes a decoder, voltage-current converter, shift current source, first and second mirror current circuits, and current switching circuits, which allow for the generation of analog signals by adding or subtracting unit currents based on decoded signals, eliminating the need for capacitors and resistors in the switching circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a resistor ladder is used to generate voltage corresponding to digital value, then the digital-analog converter can convert digital signals to analog voltages, but the current drive capability at the output is limited
Solution Approach 1:
The patent extracts the current generation function from the traditional resistor ladder structure and implements it through separate current sources (first and second current sources) that can be independently controlled. This allows the current drive capability to be improved while maintaining the digital-to-analog conversion function.
Solution Approach 2:
The patent creates a multi-functional current supply system where multiple current sources can serve different purposes simultaneously - some currents are mirrored, some are switched, and some are combined. This universal current supply architecture provides greater adaptability and degree of freedom in current supply configurations.
2Power
If a current addition type system is used to add unit current in response to decoder signals, then the converter can generate analog voltage with improved current capability, but the degree of freedom of current drive capability requires further improvement
Solution Approach 1:
The patent segments the current supply system into multiple independent current sources (first current source, second current source) with distinct functions. The first current source provides base current while the second current source provides additional controllable current. This segmentation allows independent optimization of each current source's characteristics.
Solution Approach 2:
The patent introduces dynamic control through switch circuits that can selectively connect or disconnect current paths based on decoded digital signals. The mirror current circuits dynamically adjust current distribution, and the third switch circuit dynamically controls the combination of currents from different sources, providing real-time adaptability in current supply.
3Adaptability or versatility
If traditional resistor ladder circuits are used, then the circuit structure is simple, but the current supply flexibility and adaptability are restricted
Solution Approach 1:
The patent replaces the passive resistor-based voltage division mechanism with active current sources and switch-based control mechanisms. This substitution enables dynamic, programmable control of current supply characteristics, transforming a static resistor ladder into a flexible, digitally-controlled current supply system.
Solution Approach 2:
The patent introduces mirror current circuits as intermediary components between the digital decoder and the final output. These mirror circuits act as mediators that can replicate, scale, and distribute currents from the primary current sources to multiple output paths, adding flexibility without directly complicating the core current generation architecture.
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
This configuration enhances the degree of freedom in current supply capability, enabling more flexible and efficient generation of analog signals without the limitations of traditional resistor ladder-based systems, while reducing glitches at the output.
Implementation Method 1
The constant current source includes an operational amplifier that receives a fixed reference voltage
Implementation Method 2
The constant current source includes an operational amplifier that receives a fixed reference voltage and a bipolar transistor
Implementation Method 3
a first mirror current source configured to generate a mirror current from the first mirror current circuit and the second mirror current source being configured to generate a mirror current from the second mirror current circuit
Data Source
AI summary
A digital-analog converter includes a digital-analog converter circuit connected to a first mirror current circuit that receives an additional current obtained by adding a current from a voltage-current converter circuit for generating a current according to a received voltage signal to a shift current from a shift current source and a second mirror current circuit that receives the shift current. The digital-analog converter circuit includes current switching circuits. Each current switching circuit includes a first mirror current source that provides a mirror current from one of the first and the second mirror current circuit, a second mirror current source that provides a mirror current from the other, and a switch circuit that determines whether the first and the second mirror current source of each current switching circuit contribute to a value of an analog signal at an D/A output in response to a decoded signal value.