Charge Pump Latch-Up Prevention via Dynamic Bulk Control
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Solution Overview
Problem
The charge pump circuit in semiconductor devices often experiences latch-up issues due to forward-biased diodes between the p+ diffusion region and n-well region, causing abnormal operation, especially during booting when the output voltage is lower than the internal voltage.
Innovation Solution
A charge pump circuit design that includes switching circuits and transistors to manage voltage levels and connect bulk terminals based on input and output voltages, using control signals to prevent latch-up by ensuring proper connection and disconnection of bulk terminals with input and output terminals, and incorporating capacitors for charging and discharging operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bulk terminal is connected to the output terminal during normal operation, then the threshold voltage is maintained, but latch-up occurs during booting when output voltage is lower than input voltage
Solution Approach 1:
The bulk terminal connection is made dynamic rather than static. The switching circuit changes the bulk terminal connection state based on operating conditions: connected to output terminal during normal operation for threshold voltage stability, and disconnected or connected to input terminal during booting to prevent latch-up. This dynamic adaptation resolves the contradiction between maintaining threshold voltage and preventing latch-up.
Solution Approach 2:
The invention changes the voltage parameter at the bulk terminal based on operating phase. During booting, the bulk terminal voltage is controlled to match the input voltage (higher than output voltage), while during normal operation, it is controlled to match the output voltage. This parameter change prevents forward biasing of the diode during booting while maintaining proper threshold voltage during normal operation.
2Ease of operation
If the diode between p+ diffusion region and n-well region is forward-biased during booting, then the bulk terminal voltage is lower than input voltage, but this causes latch-up and abnormal operation
Solution Approach 1:
The invention applies preliminary anti-action by preventing the harmful forward bias condition before it can cause latch-up. The switching circuit proactively controls the bulk terminal connection during the booting phase to ensure the diode remains reverse-biased or at least not forward-biased, thereby preventing latch-up before it occurs.
Solution Approach 2:
The switching circuit performs preliminary action by establishing the correct bulk terminal connection configuration before normal operation begins. During the booting phase, it ensures the bulk terminal is connected in a way that prevents forward biasing of the diode, preparing the circuit for safe operation before the output voltage rises above the input voltage.
3Reliability
If switching circuits are added to dynamically control bulk terminal connections, then latch-up is prevented, but device complexity increases
Solution Approach 1:
The switching circuit performs multiple functions: it controls the bulk terminal connection to prevent latch-up during booting, maintains threshold voltage stability during normal operation, and manages the charging/discharging of the capacitor. By consolidating these functions into a single multi-functional switching circuit, the invention reduces overall device complexity compared to having separate circuits for each function.
Solution Approach 2:
The invention merges the bulk terminal control function with the capacitor charging/discharging control into a single switching circuit structure. The same switching transistors and control logic that manage the capacitor also control the bulk terminal connections, thereby reducing the number of separate components and simplifying the overall device structure while maintaining latch-up prevention capability.
Data Source
AI summary
A charge pump circuit configured to prevent latch-up is provided. The charge pump circuit includes a first transistor including a first bulk terminal, a first input terminal and a first output terminal, a first switching circuit connecting the first bulk terminal to one of the first input terminal and the first output terminal according to a voltage of the first input terminal and a voltage of the first output terminal, a first capacitor having a terminal connected to the first output terminal, and a second switching circuit connecting a second terminal of the first capacitor to the first input terminal or a ground in response to a plurality of clock signals.