Differential Data Transmitter Power Reduction via Transition Switch
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Solution Overview
Problem
There is a need for improved data communications systems and methods that reduce power consumption without degrading link performance for data recovery in low-power devices.
Innovation Solution
A differential data transmitter design that uses a plurality of switches to control a differential voltage output on an unterminated transmission line, with a transition switch to discharge the lines during state transitions, reducing power consumption by bringing voltages to approximately half the total voltage and matching output impedance to minimize energy dissipation and electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional differential transmitters are used to drive unterminated transmission lines, then data can be transmitted, but power consumption is high due to repeated charging and discharging of the transmission line during state transitions
Solution Approach 1:
The transmitter pre-charges the transmission line to the opposite state before actually transitioning the data state. For example, before transitioning from logic 0 to logic 1, the line is pre-charged to logic 1 voltage level. This eliminates the need to discharge the line during the actual state transition, significantly reducing power consumption.
Solution Approach 2:
The invention converts the harmful effect of charged transmission lines (which cause power loss during discharge) into a beneficial pre-charged state. By maintaining the line in a pre-charged state opposite to the current data state, the system eliminates wasteful discharge events and reduces electromagnetic interference.
2Use of energy by moving object
If a transition switch is added to discharge the transmission line during state transitions, then power consumption is reduced, but device complexity increases
Solution Approach 1:
The transition switch is integrated into the existing H-bridge driver circuit structure, sharing common components and control logic with the differential output stage. This merging approach minimizes additional circuitry while achieving the power reduction benefits.
Solution Approach 2:
The transition switch serves multiple functions: it pre-charges the transmission line to the opposite state, eliminates discharge during state transitions, and can be controlled to maintain impedance matching. This multi-functionality reduces the need for separate circuits for each function.
3Use of energy by moving object
If the transmission line is discharged during state transitions, then power consumption is reduced, but electromagnetic interference may increase due to rapid voltage changes
Solution Approach 1:
The transmitter uses periodic pre-charging cycles that are synchronized with the data transmission rate. By pre-charging the line periodically before state transitions at a controlled rate, the system reduces electromagnetic interference while maintaining power efficiency.
Solution Approach 2:
The pre-charging action is performed in advance to counteract the potential harmful voltage changes during state transitions. By having the line already charged to the target voltage level, rapid voltage changes and associated electromagnetic interference are prevented.
Data Source
AI summary
Systems and methods for differential data transmission using an unterminated transmission line comprise a plurality of switches configured to control a differential voltage output on a pair of output lines, wherein the plurality of switches have a first state in which a high voltage is output on a first of the pair of output lines and a low voltage is output on a second of the pair of output lines, and wherein the plurality of switches have a second state in which the low voltage is output on the first of the pair of output lines and the high voltage is output on the second of the pair of output lines. A transition switch with an output impedance equal to that of the output lines will discharge the lines during a state transition so as to reduce to power consumption associated with changing states of the transmission line.