Definition: Negative resistance in electronic circuit means that the voltage to current relationship is inversely proportional to each other. In other words, the current across the circuit element decreases as the voltage applying across it increases.
This implies the element suddenly act as an energy source rather than an energy load.
- Negative resistance is a mathematics method to analyze oscillator response. The negative resistance of the analysis is the active circuits (BJT or MOSFET) that injects energy into the LC resonant tank to keep the oscillation going, or else the oscillation will fade away due to nonzero internal circuit resistance.
- Negative resistance is certain element such as a tunnel diode where currently initially increases as voltage increases and then the current drops when voltage continues to increase. This drop region of the tunnel diode is called negative resistance region, which means the overall diode resistance suddenly decreases as if a negative resistor is added in series to the original diode internal resistance.
- In electronic design using transient voltage suppression (TVS) diode for ESD protection circuit, the negative resistance region of the TVS diode is often refereed as the snap back region. The amount of snap back is characterize by the voltage drop. Sometimes this voltage drop or snap back is desired because it means the TVS diode can protect the sensitive circuitry at a lower voltage (i.e larger snap back means lower voltage level for protection; however too deep of a snap back can be problematic.
- Please see following links for more detailed on ESD protection design.
Reference and further reading:
- "The dangers of deep snap-back ESD circuit-protection diodes", https://e2e.ti.com/blogs_/b/analogwire/archive/2016/09/12/the-dangers-of-deep-snap-back-esd-circuit-protection-devices