Digital Feedforward Sigma-Delta Modulator Without Analog Adder
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Solution Overview
Problem
Existing sigma-delta modulators require high-speed analog adding circuits, which occupy significant area and consume high power, and also necessitate digital-to-analog conversion for feedback, complicating circuit design and increasing power consumption.
Innovation Solution
The digital feedforward sigma-delta modulator processes signals entirely in the digital domain, eliminating the need for high-speed analog circuits and digital-to-analog conversion by using integrators, multipliers, quantizers, and digital adders to perform sigma-delta modulation, thereby reducing analog circuit area and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-speed analog adding circuits are used to add up analog signals, then signal processing speed is improved, but circuit area and power consumption increase significantly
Solution Approach 1:
The patent replaces the mechanical/analog adding circuit with a digital adding circuit. Specifically, the analog signals from multiple integrators are converted to digital domain through sampling and quantization, then added using digital logic circuits. This substitution eliminates the need for high-speed analog adding circuits while maintaining signal processing capability, thereby reducing circuit area and power consumption.
Solution Approach 2:
The patent changes the domain parameter of signal processing from analog to digital. By converting analog signals to digital signals through ADC (analog-to-digital conversion) and performing addition in the digital domain, the system avoids the limitations of analog circuit speed while reducing area and power requirements. This parameter change fundamentally resolves the contradiction between speed and area/power consumption.
2Productivity
If analog adding circuits are used to process signals, then signal processing capability is maintained, but power consumption increases
Solution Approach 1:
The patent substitutes power-hungry analog adding circuits with energy-efficient digital adding circuits. The digital domain implementation uses logic gates and digital processors that consume significantly less power than high-speed analog circuitry, while maintaining equivalent or superior signal processing capability through software-defined flexibility.
Solution Approach 2:
The patent transitions the operating domain from analog to digital, which fundamentally changes the energy consumption characteristics. Digital circuits operate at lower voltages and can be optimized for low power through techniques like clock gating and power management, whereas analog circuits require continuous high-power operation to maintain signal integrity and processing speed.
3Ease of operation
If digital-to-analog conversion is used for feedback, then analog feedback signal is generated, but circuit design complexity and power consumption increase
Solution Approach 1:
The patent replaces the DAC (digital-to-analog converter) in the feedback path with a digital feedback mechanism. The feedback signal remains in the digital domain throughout the loop, eliminating the need for DAC conversion and subsequent analog processing. This substitution simplifies circuit design by removing complex conversion stages and reduces power consumption associated with high-precision DAC operation.
Solution Approach 2:
The patent changes the feedback signal domain from analog to digital. By maintaining digital signals throughout the feedback loop, the system eliminates the analog-digital conversion interface, thereby reducing design complexity related to matching analog and digital domains, managing ground loops, and ensuring signal integrity across domain boundaries.
Data Source
AI summary
A digital feedforward sigma-delta modulator in an analog-to-digital converter and its modulation method are disclosed. The modulator changes a feedforward path from an analog domain to a digital domain and processes it. The modulator integrates an analog input by using a plurality of integrators, weights them, quantizes them by using a plurality of quantizers in a digital domain to output digital signals, and then adds up the thusly outputted digital signals by using a digital adder. In case of a continuous time digital feedforward sigma-delta modulator (SDM), a digital signal outputted from the digital adder is weighted and then immediately inputted to the digital adder in the digital domain so as to be subtracted, allowing for digital feedforwarding. Because the feedforward signal is processed in the digital domain, the area occupied by an analog circuit and power consumption can be reduced. Also, because signals are added up in the digital domain, a digital output signal can be immediately used when an excess loop delay needs to be corrected. Thus, because there is no need to convert the digital output signal into an analog signal by using a DAC, the DAC can be omitted.