Digital Differential Signal Circuit With Low-Skew Switching
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Solution Overview
Problem
Conventional methods for converting single-ended digital signals to differential signals for high-speed data transmission require high power due to analog circuit implementations, leading to increased power consumption and inefficiency.
Innovation Solution
A digital circuit approach using time-balanced switching elements and sampling circuits to generate differential signals with low skew, where the first and second switching elements transition based on a selection signal with a substantially constant delay, reducing power consumption and noise immunity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current driven analog circuit is used to convert single ended digital signal to differential signal, then the conversion can be achieved, but the current demand increases and power consumption increases
Solution Approach 1:
The patent replaces the analog current-driven circuit with a digital switching-based circuit. Instead of using continuous analog current to generate differential signals, the invention uses digital switching elements (multiplexers) controlled by digital logic signals. This substitution of analog mechanism with digital mechanism significantly reduces power consumption while maintaining the differential signal generation capability.
Solution Approach 2:
The patent changes the operating parameters of the signal generation circuit by using time-balanced switching with equal rise and fall times. By controlling the switching elements to have symmetric transition characteristics, the circuit achieves low skew differential output. The selection signal transitions between logic high and logic low states, controlling the switching elements to exchange their output states, thereby generating complementary differential signals with balanced timing characteristics.
2Reliability
If conventional analog circuit techniques are used for signal conversion, then signal integrity can be maintained, but noise immunity decreases and power efficiency worsens
Solution Approach 1:
The patent replaces analog circuitry with digital switching circuits, which inherently provide better noise immunity. Digital switching elements operate with well-defined logic levels and transitions, making them more resistant to noise interference compared to analog circuits. The time-balanced switching mechanism ensures that both differential signals transition simultaneously, maintaining signal integrity while rejecting common-mode noise.
Solution Approach 2:
The patent uses two switching elements that are essentially copies of each other, both controlled by the same selection signal. These identical switching elements process the same input signal in parallel, generating complementary output signals. This copying approach ensures that both signals experience the same timing characteristics and noise conditions, enabling effective differential signaling with improved noise rejection.
3Use of energy by moving object
If digital switching elements are used to generate differential signals, then power consumption is reduced, but circuit complexity increases
Solution Approach 1:
The patent uses universal switching elements (multiplexers) that can perform multiple functions. The same switching element structure is used for both differential signal generation and time-balancing. The selection signal serves dual purposes: controlling the signal routing and ensuring time-balanced transitions. This multi-functionality reduces the need for separate dedicated circuits, thereby limiting the increase in overall circuit complexity.
Solution Approach 2:
The patent intentionally introduces asymmetric elements in a controlled manner to achieve symmetric outcomes. The selection signal transitions asymmetrically between logic states, but this controls the switching elements to produce symmetric time-balanced differential outputs. The asymmetric control signal (with potentially different rise and fall times) is used to drive the switching elements in a way that produces symmetric signal transitions, resolving the complexity issue by using controlled asymmetry to achieve desired symmetry.
Data Source
AI summary
Aspects of the disclosure provide a circuit using digital techniques to generate a differential signal with a low skew. The circuit can include a first switching element configured to receive at least a first logic value and a second logic value, and output a first signal of the differential signal, the second logic value being different from the first logic value. Further, the circuit can include a second switching element configured to receive at least the first logic value and the second logic value, and output a second signal of the differential signal. Additionally, the circuit can include a selection signal generator coupled to the first switching element and to the second switching element, the selection signal generator being configured to provide a selection signal to the first switching element and to the second switching element, the selection signal causing the first signal to transit from the first logic value to the second logic value based on the selection signal, and causing the second signal to transit from the second logic value to the first logic value based on the selection signal.