Mosfet Com Source amp with CCS load and output buffer X100

196

02:34:51

MOSFET common source amplifier. Current source increases the gain of this circuit, with a resistor load in the drain the maximum gain is quite limited due to the MOSFETs inherently low transconductance. A current source has a very high impedance with AC signals, this high impedance allows the MOSFETs low transconductance to make a reasonable amount of gain, in this case around X100

If you want to build this circuit a current source can be made using a jfet and a resistor. Don't know why jfets aren't available on this app.

published 8 years ago

gasboss775

8 years ago

Today I built a variation of this using a bs170 N ch MOSFET and a jfet based current source, I used a darlington buffer (bc517) and took feedback from the output of the buffer. The open loop gain ( with no AC -ve feedback ) was as much as x360, which is remarkable for a mosfet given their low transconductance when compared to BJT's. The CCS was 1mA and used a J113 and 750R resistor, but you might need to experiment with the resistor value due to the wide spread of jfet parameters.

add comment in editor

EveryCircuit is an easy to use, highly interactive circuit simulator and schematic capture tool. Real-time circuit simulation, interactivity, and dynamic visualization make it a must have application for professionals and academia. EveryCircuit user community has collaboratively created the largest searchable library of circuit designs. EveryCircuit app runs online in popular browsers and on mobile phones and tablets, enabling you to capture design ideas and learn electronics on the go.