Switchable Termination Resistance Circuit for Low-Power EMI Robustness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing communication systems face challenges in managing termination resistance in transceivers to reduce reflections and power consumption, especially under high electromagnetic interference and high common mode voltages, which complicates the design of switchable termination resistors.
Innovation Solution
A switchable termination resistance circuit with a driving circuit that uses a parallel arrangement of PMOS switches and a control circuit to provide and maintain termination resistance, including a high-pass filter to control current flow, reducing power consumption and enhancing robustness against electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a termination resistance is provided at the transmitter to reduce reflections, then signal quality is improved, but power consumption increases
Solution Approach 1:
The termination resistance is made switchable between connected and disconnected states based on transmission mode. During transmission, the termination resistance is connected to reduce reflections and improve signal quality. During reception, it is disconnected to minimize power consumption. This dynamic switching resolves the contradiction between maintaining signal quality and reducing power consumption.
Solution Approach 2:
The circuit changes the resistance parameter at the transmitter output by switching between a low resistance state (termination connected) and a high resistance state (termination disconnected). This parameter change allows the system to optimize for signal quality during transmission and for power consumption during reception, resolving the contradiction between these two requirements.
2Use of energy by moving object
If a switchable termination resistance circuit is implemented, then power consumption is reduced, but device complexity increases
Solution Approach 1:
The termination switching function is merged with the existing transmission/reception control logic. The same control signal that switches between transmit and receive modes is used to control the termination resistance switching. This integration avoids adding separate control circuits and minimizes overall device complexity while achieving power consumption reduction.
Solution Approach 2:
The termination resistance switch serves multiple functions: it controls reflections during transmission and manages power consumption during reception. By making this single component multi-functional, the circuit achieves power savings without requiring multiple separate control mechanisms, thereby limiting the increase in device complexity.
3Speed
If high current is provided during switching to ensure fast termination engagement, then switching speed is improved, but electromagnetic interference increases
Solution Approach 1:
The circuit uses a two-stage current provision strategy: a high current pulse is provided only during the brief switching transition to ensure fast engagement, followed by a lower sustained current to maintain the switched state. This periodic action pattern provides the necessary switching speed while minimizing continuous electromagnetic interference, resolving the contradiction between speed and EMI.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An apparatus comprising: a driving circuit; a switchable termination resistance circuit configured to selectively provide a resistance based on an output of the driving circuit; wherein the output of the driving circuit is provided by a parallel arrangement of a first branch having a first switch and a second branch having a second switch, wherein the second branch provides greater current than the first branch, and wherein the driving circuit is configured to provide, in response to an enable signal received at an input of the driving circuit, the output comprising a first current by turning on the second switch for a predetermined time period following the provision of the enable signal to cause the provision of the termination resistance, and, after said predetermined time period, turn off the second switch such that the output comprises a second current, less than the first current.