eUSB Repeater Circuit With Adaptive Edge Delay for USB Crossover
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Solution Overview
Problem
Designing low-cost repeaters for eUSB systems that meet the crossover point specification at both 1.5 Mbps and 12 Mbps signaling speeds is challenging, especially in high-volume production, as existing solutions are complex and expensive or difficult to adjust for different speeds and newer USB standards.
Innovation Solution
A repeater circuit with a multiplexer, buffer, inverter, and programmable delay capacitors that selectively apply delays to the rising or falling edges of the signal to meet the crossover specification across varying load conditions, using common output buffers and I2C control for programmable capacitance to adjust for different signaling modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple output stages connected in parallel are used to control rise time and fall time, then the crossover point specification can be met, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent changes the capacitance parameter of the delay network dynamically to adjust the delay time. By varying the capacitance value, the circuit can meet different crossover point requirements for various signaling speeds (1.5 Mbps and 12 Mbps) without requiring multiple fixed output stages, thus reducing device complexity while maintaining manufacturing precision.
Solution Approach 2:
The patent introduces a dynamic delay adjustment mechanism where the delay time can be modified based on the signaling speed mode. This dynamic capability allows a single repeater circuit to adapt to different requirements, eliminating the need for multiple static output stages and reducing overall circuit complexity.
2Device complexity
If RC network is used at the output of the driver, then the circuit complexity is reduced, but the ability to adjust for different signaling speeds is insufficient
Solution Approach 1:
The patent transforms a static RC network into a dynamic delay adjustment mechanism by introducing controllable capacitance elements. This allows the same basic RC structure to adapt its timing characteristics for different signaling speeds (1.5 Mbps and 12 Mbps), maintaining low complexity while gaining versatility.
Solution Approach 2:
The patent modifies the capacitance parameter of the delay network to adjust the delay time according to different signaling modes. This parameter change enables a single circuit design to handle multiple signaling speeds without requiring separate RC networks for each mode.
3Ease of manufacture
If fixed delay circuits are used, then the manufacturing cost is reduced, but the ability to meet crossover specification across varying load conditions is limited
Solution Approach 1:
The patent introduces programmable delay capacitors that can be configured via I2C control to adjust the delay parameter. This allows a single manufactured circuit to be programmed with different delay values to meet crossover specifications under various load conditions, maintaining low manufacturing cost while improving reliability through software-based adaptation.
Solution Approach 2:
The patent creates a universal delay circuit that can serve multiple functions by adjusting its delay parameter. The same hardware circuit can be programmed to meet crossover requirements for different load conditions and signaling modes, eliminating the need for multiple fixed-delay circuit variants and improving reliability through a single adaptable solution.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a cost-effective and reliable repeater design that meets the crossover specification for both low-speed and full-speed modes across a wide range of load conditions, without requiring adjustments to the output buffers, ensuring compatibility with legacy USB 2.0 standards and future updates.
Implementation Method 1
A repeater circuit with a multiplexer, buffer, inverter, and programmable delay capacitors that selectively apply delays to the rising or falling edges of the signal
Data Source
AI summary
A repeater circuit includes at least a first input, and output, and a repeater. The first input for receiving a single-ended data signal from an embedded universal serial bus (eUSB) host. The output provides a differential data signal in a differential universal serial bus (USB) format. The repeater is coupled between the first input and output for converting the single-ended data signal to a differential data signal, the repeater includes an adaptive delay element operable for both sides of the differential data signal to delay one, but not both, of a rising edge and a falling edge of the differential data signal in order to meet a crossover specification for the USB format.