Differential Pre-Driver Circuit for Lower Jitter Data Transmission
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Solution Overview
Problem
Transmitter circuit performance is limited by data jitter caused by variations in signal delay and RC time constants, leading to reduced data transmission speeds and increased costs due to parasitic inductance in device packages.
Innovation Solution
The implementation of a differential driver circuit with programmable capacitors and current injection mechanisms to reduce data-dependent jitter and modify the effective capacitance, thereby stabilizing the supply voltage and reducing the RC time constant, allowing for higher data transmission speeds without requiring low-inductance bond wire packages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If bond wire connections are used for device packaging, then ease of manufacture is improved, but data jitter increases due to inductance variations
Solution Approach 1:
A pre-driver circuit is introduced as an intermediary component between the driver circuit and the bond wire connection. The pre-driver circuit includes capacitors that compensate for the inductance effects of the bond wire, effectively mediating the interaction between the driver and the packaging inductance to reduce data jitter while maintaining ease of manufacture with standard bond wire packages
2Ease of manufacture
If terminal resistance and package capacitance are present, then ease of manufacture is improved, but transmission speed decreases due to RC time constant
Solution Approach 1:
The pre-driver circuit performs preliminary action by pre-charging capacitors that compensate for the RC time constant effects. These capacitors are charged in advance during normal operation and then discharge to compensate for the slow charging effects of the terminal resistance and package capacitance, effectively pre-compensating for the RC limitation and enabling faster transmission speeds while maintaining ease of manufacture
3Productivity
If data transmission speed is increased, then productivity is improved, but data jitter increases due to circuit performance limitations
Solution Approach 1:
The pre-driver circuit with its capacitors provides a form of feedback compensation. The capacitors charge and discharge in response to the signal transitions, providing feedback current that compensates for the inductance and RC effects. This feedback mechanism allows the system to maintain low data jitter even at higher transmission speeds, thereby improving productivity without sacrificing reliability
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 timing jitter and increases data transmission speed by stabilizing the supply voltage and modifying the RC time constant, while also optimizing power consumption and reducing manufacturing costs.
Implementation Method 1
each pre-driver includes one or more capacitors, a first end of each capacitor being connected to the output of the pre-driver and a second end of each of the capacitors being connected to a sub-pre-driver circuit
Implementation Method 2
a first pre-driver and a second pre-driver, where each pre-driver has an output, wherein the first output terminal of the apparatus is coupled to the output of the first pre-driver, and the second output terminal of the apparatus is coupled to the output of the second pre-driver
Data Source
AI summary
Embodiments of the invention are generally directed to elements to counter transmitter circuit performance limitations. An embodiment of an apparatus for driving data on a differential channel including a first output terminal and a second output terminal includes a differential driver circuit; and a first pre-driver and a second pre-driver, where each pre-driver has an output, wherein the first output terminal of the apparatus is coupled to the output of the first pre-driver, and the second output terminal of the apparatus is coupled to the output of the second pre-driver, where each pre-driver includes one or more capacitors, a first end of each capacitor being connected to the output of the pre-driver and a second end of each of the capacitors being connected to a sub-pre-driver circuit.