Figure 4 shows an example of a MOSFET with the gate divided into N = 6 sections. The voltage, ΔV, does not contribute to output power and simply degrades efficiency.ĭividing the gate into multiple sections is applicable to all types of FETs. Over the length, ΔL, the resistance is quite large and the power dissipated in this resistance is equal to the product of the saturated current and ΔV. This explains why the value of the drain current is nearly constant for drain voltages greater than V Dsat. The drain current, which is equal to V Dsat divided by this resistance, hardly changes.
![shreddage x how to use pinch harmonics shreddage x how to use pinch harmonics](https://i.ytimg.com/vi/5I5O8P-r5Rk/hqdefault.jpg)
For ΔL << L, which represents the usual case, depletion from the source to the pinch-off point is essentially identical in shape, and the channel has approximately the same resistance from the source to the point where pinch-off occurs. Voltage, ΔV, is dropped across this depleted region and, due to its high resistivity, ΔL is very small. Over the length, ΔL, the channel is completely depleted, and the resistance is quite large. 1 If the drain voltage is increased by ΔV, the point at which pinch-off occurs moves toward the source a distance ΔL (see Figure 1b).
![shreddage x how to use pinch harmonics shreddage x how to use pinch harmonics](https://i0.wp.com/worldpremiumware.com/wp-content/uploads/2020/04/DS-Simulia-Next-Limit-xFlow-2020.jpg)
When the drain voltage of a JFET, for instance, is equal to V Dsat, pinch-off occurs exactly at the drain of the transistor (see Figure 1a).
![shreddage x how to use pinch harmonics shreddage x how to use pinch harmonics](https://www.samplelibraryreview.com/wp-content/uploads/2021/01/Review-Shreddage3Legacy_-Impact-Soundworks.jpg)
To understand the degradation of efficiency, consider the behavior of a FET in saturation. Under this condition, the FET is in saturation, where the drain current is not a function of the drain voltage and is only a function of the gate voltage. The efficiency of a FET is degraded when its drain voltage is greater than V Dsat, the voltage at which pinch-off first occurs. Figure 1 Channel of a JFET with the drain voltage equal to the pinch-off voltage (a) and the drain voltage exceeding the pinch-off voltage (b).