Tri-Level DAC Architecture for Lower Power and Flicker Noise
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Solution Overview
Problem
Existing 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 a reference voltage and half to ground, leading to inefficient power usage and increased noise.
Innovation Solution
A tri-level digital-to-analog converter is introduced, which includes a third reference voltage to reduce power consumption and flicker noise by coupling resistors to this voltage instead of ground, and uses delta-sigma modulation and shuffling techniques to control common mode current and improve precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a switched resistor DAC connects half of the resistors to reference voltage and half to ground, then the DAC can generate the required analog signal, but power consumption increases and flicker noise is generated
Solution Approach 1:
The patent changes the voltage parameter by introducing a third reference voltage (Vx) that is intermediate between the positive reference voltage (Vr) and ground. This allows resistors to be connected to Vx instead of ground, reducing the voltage across them and thereby reducing both power consumption (P=V²/R) and flicker noise generated by the resistors.
Solution Approach 2:
The patent introduces an intermediary voltage level (Vx) that acts as a mediator between the positive reference voltage and ground. By connecting resistors to this intermediary voltage rather than directly to ground, the system reduces the voltage differential across the resistors, which simultaneously reduces power consumption and flicker noise while maintaining the ability to generate the required analog output signal.
2Measurement precision
If precision DAC elements are used to achieve high conversion precision, then conversion accuracy improves, but manufacturing difficulty and element matching complexity increase
Solution Approach 1:
The patent applies equipotentiality by connecting resistors to the intermediate voltage Vx, which creates a more balanced voltage environment. This reduces the stress and voltage differential across individual resistor elements, making their electrical characteristics more uniform and easier to match during manufacturing, thereby achieving high conversion precision without requiring extremely tight manufacturing tolerances.
Solution Approach 2:
By changing the operating voltage parameter of the DAC elements from the traditional two-level (Vr and ground) to a three-level system (Vr, Vx, and ground), the patent creates more favorable operating conditions for the resistors. This parameter change reduces the voltage stress on individual elements, making their characteristics more consistent and easier to match,从而 achieving high precision with relaxed manufacturing requirements.
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.