Charge Pump Circuit Substrate Biasing
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Solution Overview
Problem
The existing charge pump circuits face issues with abnormal voltage boosting due to the turning-on of parasitic bipolar transistors, which prevents stable operation of both positive and negative electric potential generating charge pump circuits.
Innovation Solution
Incorporating a clamp diode to prevent forward current flow from the semiconductor substrate to the diffusion layer when the positive electric potential generating charge pump circuit is in operation, and controlling the sequence of operations to ensure the negative electric potential generating charge pump circuit biases the semiconductor substrate before the positive electric potential generating charge pump circuit starts, thereby preventing parasitic bipolar transistor activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the positive electric potential generating charge pump circuit is operated, then positive electric potential is generated, but substrate current flows into the P-type semiconductor substrate causing abnormal voltage boosting
Solution Approach 1:
The negative electric potential generating charge pump circuit is operated first to apply a negative electric potential to the P-type semiconductor substrate before operating the positive electric potential generating charge pump circuit. This preliminary action biases the substrate to prevent parasitic bipolar transistor activation and abnormal voltage boosting when the positive charge pump is activated.
Solution Approach 2:
A negative electric potential is applied to the P-type semiconductor substrate in advance to counteract the harmful substrate current effect. By establishing a negative bias on the substrate before the positive charge pump operates, the parasitic bipolar transistor is prevented from turning on, thereby counteracting the abnormal voltage boosting effect.
2Adaptability or versatility
If both charge pump circuits are controlled to start simultaneously or sequentially, then both positive and negative electric potentials can be generated, but parasitic bipolar transistor activation occurs
Solution Approach 1:
The negative electric potential generating charge pump circuit is operated first to establish a negative bias on the P-type semiconductor substrate before the positive electric potential generating charge pump circuit is activated. This sequential operation prevents parasitic bipolar transistor activation while enabling both charge pump circuits to function reliably.
Solution Approach 2:
The charge pump circuits are operated in a specific periodic sequence where the negative charge pump operates first to bias the substrate, followed by the positive charge pump operation. This periodic control pattern ensures stable operation of both circuits without causing abnormal voltage boosting.
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
This solution allows for normal voltage boosting operations by preventing parasitic bipolar transistor activation, ensuring stable output potentials for both positive and negative electric potential generating charge pump circuits.
Implementation Method 1
a clamp diode that clamps an electric potential of the semiconductor substrate to prevent a forward current from flowing from the semiconductor substrate to the diffusion layer
Data Source
AI summary
In a charge pump circuit provided with a positive electric potential generating charge pump circuit that generates a positive electric potential and a negative electric potential generating charge pump circuit that generates a negative electric potential, a parasitic bipolar transistor is prevented from turning on so that the charge pump circuit performs normal voltage boosting operation. First, the negative electric potential generating charge pump circuit is put into operation to generate −VDD as an output electric potential LV. Since the output electric potential LV is applied to a P-type semiconductor substrate, an electric potential of the P-type semiconductor substrate becomes −VDD. After that, the positive electric potential generating charge pump circuit is put into operation while the negative electric potential generating charge pump circuit continues its operation. The positive electric potential generating charge pump circuit performs the normal operation, because the electric potential of the P-type semiconductor substrate is −VDD. After the output electric potential HV of the positive electric potential generating charge pump circuit reaches 2VDD, the negative electric potential generating charge pump circuit is put into a second operation mode (inverting HV).