Output Transistor Gate Control for Slew Rate and EMI Balance
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Solution Overview
Problem
Existing signal transmitting apparatuses face challenges in simultaneously meeting the requirements for high output signal slew rate and low radiation noise performance, particularly when the power supply voltage varies within a wide range.
Innovation Solution
The apparatus employs a charge-discharge circuit that adjusts the charge and discharge currents nonlinearly with respect to the power supply voltage, ensuring the output slew rate is maintained while minimizing radiation noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the output signal slew rate is increased to meet performance requirements, then the output signal performance is improved, but radiation noise increases
Solution Approach 1:
The patent implements dynamic control of the output transistor's on-resistance by adjusting the drive signal characteristics. The control circuit modifies the gate voltage waveform to achieve varying resistance values during different portions of the signal transition, thereby dynamically optimizing the balance between slew rate and radiation noise emission.
Solution Approach 2:
The patent changes the electrical parameters of the output stage by adjusting the drive signal voltage and timing characteristics. This enables control over the transistor's operating point and resistance profile, allowing optimization of both signal performance and electromagnetic radiation characteristics through parameter adjustment.
2Adaptability or versatility
If the power supply voltage varies within a wide range, then the adaptability of the apparatus is improved, but maintaining consistent output performance becomes more difficult
Solution Approach 1:
The patent incorporates a control circuit that monitors the power supply voltage and adjusts the drive signal characteristics accordingly. This feedback mechanism ensures that the output transistor operates within optimal parameters across different supply voltages, maintaining consistent signal performance and radiation noise characteristics despite voltage variations.
Solution Approach 2:
The patent designs the control circuit to perform multiple functions: it adapts to different power supply voltages, controls the output transistor's resistance profile, and maintains consistent output performance. This multi-functional approach enables the apparatus to operate reliably across a wide voltage range while meeting both signal quality and radiation noise requirements.
Data Source
AI summary
An output terminal is connected to an application terminal of a power supply voltage via a pull-up resister and a backcurrent prevention diode. An output transistor is disposed between the output terminal and a ground. A capacitor is connected between the gate of the output transistor and the output terminal. A charge-discharge circuit charges or discharges the gate of the output transistor in accordance with an input signal, and thus turns on or off the output transistor, so as to generate an output signal corresponding to the input signal, at the output terminal. The charge-discharge circuit set a charge current and a discharge current of the gate of the output transistor as an adjustment target current, and changes the adjustment target current nonlinearly in accordance with the power supply voltage.