ODT Termination Control for Low-Noise Bidirectional Data Lines
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Solution Overview
Problem
In semiconductor integrated circuits, power-supply noise on bidirectional signal lines causes inaccurate data transmission and reception due to sudden fluctuations in power supply voltage, especially when the receiver circuit switches off the ODT function, affecting subsequent data transmission.
Innovation Solution
A semiconductor integrated circuit with a termination circuit comprising a resistor and a switch, controlled by a control circuit to manage the ODT function, ensuring it remains on for a predetermined period after data reception to reduce power-supply noise, thereby enabling accurate data transmission and reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the receiver circuit switches off the ODT function after receiving data, then power consumption is reduced, but power-supply noise occurs on the bidirectional signal line causing inaccurate data transmission
Solution Approach 1:
The control circuit determines in advance whether the receiver should switch off the ODT function by checking if the transmitter-receiver is in a specific mode (e.g., write mode) before the data transmission occurs. This preliminary determination prevents the harmful action of switching off ODT during periods when another transmitter-receiver might be transmitting data, thereby avoiding power-supply noise while still allowing power savings when appropriate.
Solution Approach 2:
The control circuit continuously monitors the operational mode of the transmitter-receiver and uses this feedback information to dynamically control the ODT function. By receiving feedback about whether the device is in read or write mode, the control circuit can make informed decisions about when to switch the ODT function on or off, balancing power consumption with data transmission reliability.
2Speed
If the ODT function is switched off immediately after data reception, then switching speed is improved, but power-supply noise fluctuation increases affecting subsequent data reception
Solution Approach 1:
The control circuit performs a preliminary check of the operational mode before allowing the ODT function to switch off. By determining in advance whether the transmitter-receiver is in a mode where another device might be transmitting, the system can delay the ODT switch-off action until it is safe to do so, preventing power-supply noise fluctuations that would affect subsequent data reception.
Solution Approach 2:
The control circuit applies a preliminary anti-action by preventing the ODT function from switching off during periods when data transmission might occur from another transmitter-receiver. This preemptive measure counteracts the potential harmful effect of power-supply noise before it can occur, ensuring stable signal levels during critical transmission periods.
3Object-affected harmful factors
If the ODT function remains on continuously, then power-supply noise is reduced, but power consumption increases
Solution Approach 1:
The ODT function transitions from a static continuous-on state to a dynamic state that adapts to operational conditions. The control circuit dynamically switches the ODT function on or off based on real-time monitoring of the transmitter-receiver mode, allowing the system to optimize between power consumption and noise reduction depending on the current operational context.
Solution Approach 2:
The system changes the operational parameter of the ODT function from a fixed state to a variable state controlled by the control circuit. By changing the ODT parameter (on/off) based on the determined mode and timing, the system achieves both power savings during appropriate periods and noise reduction during critical transmission periods.
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
This solution effectively reduces power-supply noise, ensuring accurate data transmission and reception by maintaining the ODT function on for a sufficient period to prevent noise interference during subsequent data reception.
Implementation Method 1
a first termination circuit that includes a first resistor and a first switch, the first resistor being provided between a first power supply terminal and the signal line, the first switch controlling a current flowing through the first resistor
Data Source
AI summary
A semiconductor integrated circuit is described. A transmitter-receiver transmits and receives data to and from outside by a first external terminal and transmits a first control signal by a second external terminal. When another data is transmitted after the data is transmitted and when a data transmission interval from a time when the data is transmitted to a time when the another data is transmitted is equal to or smaller than a first threshold, the transmitter-receiver continuously outputs, from the first external terminal, a potential level of about ½of a potential level obtained by adding a first potential level and a second potential level, during the data transmission interval, and changes the second potential level of the first control signal to the first potential level when the data transmission interval exceeds the first threshold.