Active Termination Circuit With Dynamic Impedance for Low-Power Bandwidth
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Solution Overview
Problem
Current semiconductor memory devices face bandwidth restrictions due to parasitic capacitance, which limits data throughput, and existing active termination solutions require significant space and increase power consumption.
Innovation Solution
An active termination circuit using a pair of diode-connected transistors with inherent bias, where one transistor terminates signals at a low logic level and the other at a high logic level, implemented within an integrated circuit to provide dynamic termination impedance with reduced power consumption and space requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lower impedance receiver termination is used to increase bandwidth, then data throughput is improved, but power consumption increases
Solution Approach 1:
The termination impedance is made dynamic by using transistors that can switch between different impedance states based on the signal level. The circuit transitions from a static resistive termination to a dynamic active termination that adjusts its impedance characteristics, allowing low impedance during signal transitions (improving bandwidth) and high impedance during steady states (reducing power consumption).
Solution Approach 2:
The active termination circuit operates periodically, providing low impedance only during the brief periods when signal transitions occur (edges), and returning to high impedance during stable logic levels. This periodic activation of low impedance state achieves bandwidth improvement without continuous power consumption associated with maintaining low impedance throughout the entire signal cycle.
2Productivity
If active termination circuits with feedback loops and current mirrors are used to achieve low impedance, then bandwidth is improved, but device area increases
Solution Approach 1:
The invention extracts and eliminates unnecessary components from conventional active termination circuits. By removing the feedback loop, current mirror, and additional current sources, the design retains only the essential elements (transistors and resistors) needed to achieve low impedance during transitions, significantly reducing the device area while maintaining bandwidth performance.
Solution Approach 2:
The termination circuit uses the signal itself to control the termination impedance without requiring external feedback. The transistors are directly controlled by the incoming signal voltage, making the circuit self-regulating and eliminating the need for feedback pathways, thereby reducing complexity and area.
Data Source
AI summary
An active termination circuit comprising an input node connected to a transmission line, a first transistor, and a second transistor. The transmission line supplies a signal to the input node. The first transistor is diode connected between a high voltage supply and the input node. The first transistor terminates the signal when the signal is at a low logic level. The second transistor is diode connected between the input node and a low voltage supply. The second transistor terminates the signal when the signal is at a high logic level.