Pulse-Shaping Amplifier Circuit for Low-RFI Data Pulses
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Solution Overview
Problem
Existing amplifier systems in electronic circuits face inefficiencies due to amplitude ringing and conduction losses, which can lead to decreased performance and corruption of data transmission, especially in high-speed communication standards like PSI5, where radio frequency interference (RFI) is a significant concern.
Innovation Solution
A pulse-shaping amplifier system is implemented, utilizing a Class AB amplifier with a pair of transistor devices interconnected between power voltages, where the second power voltage's amplitude changes in response to the reference voltage pulse, providing a gradual increase in the amplified pulse to mitigate RFI, and an adaptive gate bias system controls the output stage to generate a shaped output voltage pulse that complies with communication timing requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional amplifier is used to generate voltage pulses in PSI communication, then the data transmission speed can be maintained, but amplitude ringing and conduction losses occur which corrupt data transmission and reduce efficiency
Solution Approach 1:
The amplifier system dynamically adjusts the power supply voltage to the output stage during pulse generation. The second power supply voltage is increased during the pulse transition period to enable faster voltage changes and reduce ringing, then returns to normal levels afterward. This dynamic adjustment allows the system to maintain high-speed data transmission while eliminating amplitude ringing that would otherwise corrupt the signal integrity.
Solution Approach 2:
The system changes the electrical parameters of the amplifier by adjusting the power supply voltage levels. Specifically, the second power supply voltage connected to the output stage is temporarily increased during pulse transitions to reduce conduction losses and eliminate ringing. This parameter change enables the amplifier to operate in different modes depending on the signal requirements, maintaining both high-speed transmission and signal integrity.
2Speed
If the slew rate of the voltage pulse is increased to meet timing requirements, then communication speed is improved, but radio frequency interference (RFI) increases
Solution Approach 1:
The system dynamically controls the power supply voltage to the output stage based on the pulse timing requirements. By temporarily increasing the second power supply voltage during critical transition periods, the system achieves the necessary slew rate for high-speed communication without maintaining high voltage levels continuously, thereby reducing RFI generation while meeting timing constraints.
Solution Approach 2:
The amplifier system performs preliminary action by pre-charging the output stage with increased power supply voltage before the actual data pulse is transmitted. This preparation allows the output stage to rapidly respond to the input signal without generating excessive RFI during the transition, as the high voltage is applied only briefly when needed for the pulse edge rather than continuously.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
In described examples, an amplifier system (10) includes an input stage (12) configured to receive an input pulse signal and to generate a reference voltage pulse based on the input pulse signal. The amplifier system (10) also includes an amplifier stage (14) that receives at least one power voltage and is configured to amplify the reference voltage pulse and to provide pulse-shaping of the amplified reference voltage pulse based on a change of amplitude of the at least one power voltage resulting from an amplitude of the reference voltage pulse.