Current Sources and Voltage References

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Using the enhancement-mode MOSFET as a current source

So it is important to use a heatsink for most power MOS applications, and this will

include higher-power current sources and sinks, which we will look at next.

8.2 Using the enhancement-mode MOSFET as a current source

The simplest current source using an N-channel power MOSFET can be made with a

zener diode and a bias resistor on the gate, as shown in Figure 8.14. Simply changing

the FET’s drain connection enables one to create either a current source or a current

sink. In this circuit, the zener’s voltage determines the MOSFET’s gate voltage, and

thereby its drain current (typically ranging from ...