Current Drive Circuit With Gate Boosting at Low Drain Voltage
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Solution Overview
Problem
Existing current drive circuits for semiconductor integrated circuits face issues such as narrow output voltage range when in non-saturation region, increased power consumption, and inability to decrease drain voltage due to series-connected transistors and ESD resistors, which limit current output and increase electrostatic discharge risks.
Innovation Solution
A current drive circuit design that includes an output transistor with a drain connected to a load and a source connected to a common potential, using a series of transistors and current sources to manage gate voltage and current, along with an ESD resistor network to maintain stable current delivery and protect against voltage surges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If transistors are connected in series to increase output voltage range, then the saturation region is expanded, but the drain terminal voltage cannot be decreased and voltage margin is absorbed by threshold voltage
Solution Approach 1:
The patent divides the current drive function into multiple parallel transistor branches instead of using a single series-connected transistor chain. Each branch contains transistors configured to provide current drive capability, allowing the circuit to achieve wide output voltage range while maintaining flexibility in drain terminal voltage control. The parallel structure eliminates the voltage margin absorption problem of series connections.
2Area of stationary object
If circuit area is decreased to reduce size, then integration is improved, but ESD resistor decreases voltage causing drive circuit to enter non-saturation region
Solution Approach 1:
The patent introduces compensation transistors and control circuits as intermediary elements that actively compensate for the voltage drop caused by the ESD resistor. These intermediary components sense the voltage reduction and adjust the gate voltages of the drive transistors accordingly, maintaining operation in the saturation region even when the ESD resistor causes voltage decrease due to small circuit area.
3Area of stationary object
If output transistor size is reduced to decrease driver size, then circuit area is reduced, but large gate voltage is necessary to output large current
Solution Approach 1:
The patent employs dynamic gate voltage control through multiple control terminals that can independently adjust the gate voltages of the output transistors. This dynamic control allows the circuit to optimize the gate voltage level based on the required output current, reducing the gate voltage requirement for large current output while maintaining small driver size. The control circuits adaptively adjust transistor operating points to minimize power consumption.
Data Source
AI summary
A current drive circuit allows for a reduction in chip size and prevents an output current from decreasing. The current drive circuit has an output terminal connected to a first resistor. The first resistor is connected to a second resistor and the drain of a first transistor. The gate of the first transistor is connected to the gate of a second transistor, a grounded first current source, and the source of a third transistor. A second current source and the third transistor are connected to a power supply line. The second current source is connected to the gate of the third transistor, the drain of a fourth transistor, the drain of a fifth transistor, and a second resistor. When the voltage decreases, the on resistance of the fourth transistor increases, the fifth transistor is then connected in series to the second transistor, which increases the gate voltage of the first transistor.