Signal-Dependent Common-Mode Control in Differential DAC Circuits
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Solution Overview
Problem
Conventional differential DACs have a fixed common-mode DC voltage setting, which limits their performance at low signal levels, leading to suboptimal noise, distortion, and power consumption.
Innovation Solution
Implementing a dynamic common-mode adjustor that varies the offset of the differential signal based on the magnitude of the input signal, allowing for signal-dependent common-mode control to enhance system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a fixed common-mode DC voltage setting is used in a conventional differential DAC, then the full-scale output signal swing is optimized, but the performance at low signal levels deteriorates with increased noise, distortion, and power consumption
Solution Approach 1:
The patent applies the dynamics principle by transitioning from a fixed common-mode voltage setting to a dynamic common-mode adjustor that automatically varies the common-mode voltage based on the instantaneous magnitude of the input signal. This dynamic adjustment allows the system to adapt to different signal levels, optimizing performance at low signal levels while maintaining efficiency at full scale, thereby resolving the contradiction between power consumption and low-signal performance.
Solution Approach 2:
The patent implements parameter changes by modifying the common-mode voltage parameter as a function of the input signal magnitude. The dynamic common-mode adjustor changes the common-mode voltage parameter dynamically, allowing the system to operate at optimal common-mode settings for different signal levels, thus improving noise, distortion, and power consumption characteristics at low signal levels without sacrificing full-scale performance.
2Adaptability or versatility
If a fixed common-mode DC voltage setting is used, then the circuit structure remains simple, but the adaptability to different signal magnitudes deteriorates
Solution Approach 1:
The patent applies the self-service principle by designing a dynamic common-mode adjustor that automatically adjusts the common-mode voltage based on the input signal magnitude without requiring external control or complex circuitry. The adjustor derives control signals from the input signal itself, enabling the system to adapt to different signal magnitudes autonomously while maintaining relatively simple circuit implementation.
3Object-affected harmful factors
If a fixed common-mode setting is used to optimize full-scale output, then the system is simple to operate, but the noise and distortion performance at low signal levels deteriorates
Solution Approach 1:
The patent implements feedback by using the input signal magnitude as feedback to control the common-mode voltage setting. The dynamic common-mode adjustor continuously monitors the input signal level and adjusts the common-mode voltage accordingly, creating a closed-loop system that automatically optimizes noise and distortion performance at different signal levels while requiring no user intervention, thus maintaining ease of operation.
Data Source
AI summary
An apparatus such as an electronic circuit includes an input operable to receive an input signal; a dynamic common mode adjustor operable to: i) derive a differential signal from the received input signal, and ii) control an offset of the differential signal as a function of the received input signal to produce an offset differential signal; and an output operable to output the offset differential signal. In one arrangement, the offset differential signal outputted from the output includes a first signal and a second signal; a difference between the second signal and the first signal proportionally varies with respect to the received input signal.