Transceiver I/O Pad Capacitance Reduction Using Resistor Dividers
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Solution Overview
Problem
In bidirectional I/O circuits, the transmitter often contributes more capacitance to the I/O pad than the receiver, degrading the receiver's performance and causing interference between signal drivers.
Innovation Solution
The implementation of resistor dividers within the I/O circuit to reduce the gate voltage of signal drivers, thereby reducing their capacitance and minimizing interference between signal drivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the transmitter uses current mode logic with large current load, then the transmitter can drive signals effectively, but the transmitter contributes greater capacitance to the I/O pad which degrades the receiver's performance
Solution Approach 1:
The patent segments the capacitance contribution by introducing a switchable capacitor bank that can be independently controlled from the transmitter. This allows the transmitter to maintain its driving capability while the receiver's capacitive load can be separately managed and reduced when the transmitter is active, thus resolving the contradiction between transmitter power and receiver reliability.
Solution Approach 2:
The patent implements dynamic capacitance management by making the capacitor bank switchable based on the operational state of the transmitter and receiver. When the transmitter is active, the capacitor bank can be configured to reduce the capacitive load on the receiver, and vice versa. This dynamic adjustment resolves the contradiction by adapting the capacitance to the current operational requirements.
2Object-affected harmful factors
If extensive layout optimization and Tcoils are added to the I/O pad, then pin capacitance can be reduced, but the complexity of the circuit increases and does not address interference between signal drivers
Solution Approach 1:
The patent changes the electrical parameters of the I/O pad by introducing switchable capacitor banks that can dynamically adjust the capacitance value. Instead of relying on complex physical layout optimizations and Tcoils, the patent uses electrical parameter adjustment (capacitance switching) to reduce pin capacitance and address signal driver interference, thereby reducing circuit complexity while achieving the desired effect.
3Reliability
If the gate voltage of the signal driver is reduced, then the capacitance of the signal driver is reduced, but the signal driver's driving capability may be compromised
Solution Approach 1:
The patent implements periodic switching of the capacitor bank based on the operational state of the signal drivers. When one signal driver is active, the capacitor bank is configured to reduce capacitance for that driver while maintaining appropriate voltage levels. This periodic adjustment allows the system to maintain driving capability during active periods while reducing capacitive effects, thus resolving the contradiction between reliability and power.
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 approach effectively reduces the undesirable impact of one signal driver's capacitance on another, thereby improving the performance of both signal drivers and enhancing signal integrity.
Implementation Method 1
Signal drivers can be coupled to resistor dividers within the I/O circuit. A gate voltage of the signal driver can be reduced by resistor dividers in order to reduce the capacitance of the signal driver.
Data Source
AI summary
Systems, methods and apparatus are provided for transceiver capacitance reduction. An example apparatus can comprise a first signal driver of a transceiver, a second signal driver of the transceiver, and an input/output (I/O) pad coupled to the first and second signal drivers. The apparatus can further comprise a resistor divider of a plurality of resistor dividers coupled to the first signal driver. The resistor divider, when enabled, can reduce capacitance of the first signal driver and maintain the reduced capacitance while the second signal driver is actively driving a signal.