Multi-feed Detection Drive Circuit Using Dual N-type MOSFETs
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Solution Overview
Problem
Existing multi-feed detection devices using push-pull circuits with N-type and P-type MOSFETs suffer from slow driving speed due to the slower drive speed of P-type MOSFETs, which limits the overall performance of the circuit.
Innovation Solution
A multi-feed detection device is designed with a drive circuit that includes a conversion circuit, a booster circuit, a first adjustment circuit to extend the rising time of the signal, a push-pull circuit using two N-type MOSFETs, and a second adjustment circuit to advance the falling timing of the signal, allowing for increased driving speed and reduced shoot-through current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a push-pull circuit uses both N-type MOSFET and P-type MOSFET, then the circuit can provide bidirectional current drive capability, but the driving speed becomes slow due to the slower drive speed of P-type MOSFET
Solution Approach 1:
The patent applies homogeneity by using two N-type MOSFETs instead of mixing N-type and P-type MOSFETs. This creates a homogeneous circuit configuration where both transistors have identical characteristics and drive speeds, eliminating the speed limitation imposed by P-type MOSFETs while maintaining the push-pull circuit's bidirectional current drive capability through symmetric switching operation.
2Reliability
If the rising time of the converted signal is extended, then the shoot-through current is suppressed, but the response time of the circuit increases
Solution Approach 1:
The patent applies preliminary action by extending the rising time of the converted signal before it is applied to the push-pull circuit. This preliminary signal conditioning ensures that the gate voltage rises gradually, which suppresses shoot-through current by preventing both N-type MOSFETs from being simultaneously on. The extended rising time is compensated by the high-speed N-type MOSFETs that can still switch rapidly once the gate voltage reaches the threshold.
Data Source
AI summary
A drive circuit including a push-pull circuit is a circuit in which a converted signal whose voltage level is inverted compared with a reference signal is input to the gate terminal of a first N-type MOSFET, and the reference signal is input to the gate terminal of a second N-type MOSFET. A second adjustment circuit advances the falling timing of the converted signal input to the gate terminal of the first N-type MOSFET.