Capacitive Inverter Level Shifting to Reduce Data Dependent Jitter
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Solution Overview
Problem
Traditional level shifting circuits in high-speed transmitting apparatuses suffer from Data Dependent Jitter (DDJ) due to an unequal tripping point for random data inputs, which affects the accurate interpretation of serial data.
Innovation Solution
A circuit employing inverter logic with a capacitor to charge and drive transistors, shifting the data voltage from a serializer to a higher source voltage, using a delayed clock signal to synchronize the switching of transistors and reduce jitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional level shifter circuits use cascoded transistors with continuous data input, then voltage level shifting from digital to analog supply voltage is achieved, but Data Dependent Jitter is introduced due to unequal tripping point
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor to a voltage equivalent to the difference between source voltage and data voltage before the data arrives. This pre-charging ensures that when the data transitions occur, the transistor switching is synchronized and the tripping point is precisely at half the data voltage, eliminating Data Dependent Jitter while maintaining reliable voltage level shifting from digital to analog supply voltage levels
Solution Approach 2:
The patent changes the voltage parameter of the capacitor dynamically - charging it to a specific voltage equivalent to the difference between source voltage and data voltage. This parameter change enables the transistor gate to reach the correct tripping point (half of data voltage) for synchronized switching, resolving the contradiction between reliability and measurement precision by adjusting the voltage parameter to achieve equal rise and fall times
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
The solution effectively reduces Data Dependent Jitter, improves signal integrity by ensuring accurate voltage level shifting, and enhances the reliability of high-speed data transmission.
Implementation Method 1
A capacitor is connected to an input of the first transistor and configured to drive the first transistor. The capacitor is configured to charge to a charged voltage equivalent to a difference between the source voltage and the data voltage.
Data Source
AI summary
The present disclosure relates to a circuit for level shifting of a data voltage from a transmitter. The circuit comprises an inverter logic. The inverter logic comprises a first transistor and a second transistor. The first transistor is connected to a source voltage and the second transistor is connected to ground. A capacitor is connected to an input of the first transistor and configured to drive the first transistor. The capacitor is configured to charge to a charged voltage equivalent to a difference between the source voltage and the data voltage. The second transistor is configured to be driven by the data voltage, thereby level shifting a level of the data voltage to a level of the source voltage.