Tri-Level DAC Architecture for Lower Power and Flicker Noise
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Solution Overview
Problem
Conventional digital-to-analog converters (DACs) face challenges in reducing power consumption and flicker noise, particularly in small input signal cases where half of the resistors are connected to reference voltage and ground, leading to inefficiencies and increased noise due to common mode current.
Innovation Solution
A tri-level digital-to-analog converter is introduced, utilizing three reference voltages and a network of unit DAC elements with switches controlled by input signals to generate three output values, reducing power consumption and flicker noise by minimizing common mode current and incorporating a third reference voltage to balance resistor connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a switched resistor DAC is used with parallel network of DAC elements, then the digital signal can be converted to analog signal, but power is wasted due to resistors being connected to reference voltage and ground simultaneously
Solution Approach 1:
The patent changes the reference voltage parameter from two levels (reference voltage and ground) to three levels (positive reference voltage, negative reference voltage, and ground). This allows the resistors to be connected to appropriate reference voltages based on the digital input, minimizing the number of resistors simultaneously connected to reference voltage and ground, thereby reducing power waste.
Solution Approach 2:
The patent dynamically switches the connection of each resistor to different reference voltages based on the digital input signal. Each resistor can be connected to positive reference voltage, negative reference voltage, or ground depending on the input bit value, allowing the system to adapt its power consumption to the actual signal requirements rather than maintaining static connections.
2Reliability
If resistors are connected to reference voltage and ground in small input signal cases, then the DAC can operate, but common mode current increases causing flicker noise
Solution Approach 1:
The patent introduces a third reference voltage level (negative reference voltage) in addition to the traditional positive reference voltage and ground. This allows the common mode voltage to be adjusted and optimized, reducing the common mode current flowing through the resistors and feedback resistors of the amplifier, thereby minimizing flicker noise generation.
Solution Approach 2:
The negative reference voltage acts as an intermediary potential level that allows the DAC to operate with reduced common mode current. By providing this intermediate voltage level, the system can maintain signal quality while reducing the harmful common mode current that causes flicker noise in the amplifier stages.
Data Source
AI summary
Methods, systems, and apparatuses for converting a digital input signal to an analog output signal are disclosed. A first delta-sigma modulator receives a common mode reference signal and generates a common mode control signal. A data delta-sigma modulator receives a digital input signal and generates a modulated digital input signal. A shuffler receives the modulated digital input signal and the common mode control signal and generates a shuffled digital input signal. A digital to analog converter (DAC) has a plurality of tri-level unit DAC elements each receiving a corresponding portion of the shuffled digital input signal as a first input signal, and receiving second and third input signals. The tri-level unit DAC elements have first outputs coupled together generating a first output signal and second outputs coupled together generating a second output signal. An operational amplifier receives the first and second output signals and generates the analog output signal.