aht2000
Junior Member level 3
I am trying to understand when to use JFET in an RF design. The band in mind is the FM Band (88-108MHz). I have seen statements like "This oscillator will only work using a JFET not a BJT as its active device" and other statements like "for our low noise front end, we will be using a JFET", ... etc
My basic understanding of JFETs is that their gain is low compared to BJTs, their parameters differ considerably from device to the other even within the same part number, not sure if they operate successfully with low supply voltages like 5V or 3.3V. They have very high input impedance as their gate is isolated, but this is only in low frequency bands (audio ?), once the frequency increases, the device input impedance comes into play and ruin the high input impedance advantage.
In BJTs, there are low power, high power, audio, RF, low noise,... etc type of devices, I assume the same exists for JFETs?
My basic understanding of JFETs is that their gain is low compared to BJTs, their parameters differ considerably from device to the other even within the same part number, not sure if they operate successfully with low supply voltages like 5V or 3.3V. They have very high input impedance as their gate is isolated, but this is only in low frequency bands (audio ?), once the frequency increases, the device input impedance comes into play and ruin the high input impedance advantage.
In BJTs, there are low power, high power, audio, RF, low noise,... etc type of devices, I assume the same exists for JFETs?