Transcription of The FET Constant-Current Source/Limiter
{{id}} {{{paragraph}}}
AN103 Siliconix10-Mar-97 1 The FET Constant-Current Source/LimiterIntroductionThe combination of low associated operating voltage andhigh output impedance makes the FET attractive as aconstant- current source. An adjustable- current source (Fig-ure 1) may be built with a FET, a variable resistor, and asmall battery. For optimum thermal stability, the FET shouldbe biased near the zero temperature coefficient +Figure Transistor current SourceRSRLNO TAGW henever the FET is operated in the current saturated re-gion, its output conductance is very low. This occurswhenever the drain-source voltage VDS is at least 50%greater than the cut-off voltage VGS(off). The FET may bebiased to operate as a Constant-Current source at any cur-rent below its saturation current Source BiasingFor a given device where IDSS and VGS(off) are known, theapproximate VGS required for a given ID is(1)VGS VGS(off) 1 IDIDSS 1 k where k can vary from to , depending on device ge-ometry.
AN103 Siliconix 10-Mar-97 5 Choosing the Correct JFET for Source Biasing Each of the Siliconix device data sheets include typical transfer curves that …
Domain:
Source:
Link to this page:
Please notify us if you found a problem with this document:
{{id}} {{{paragraph}}}
JFET, ENHANCED-JFET LOW-OFFSET, Enhanced-jfet low-offset operational amplifiers, 11EDCField-effect transistorUnivMalasiya, AN-32 FET Circuit Applications, Junction Field Effect Transistor Theory, Junction Field Effect Transistor Theory and Applications, Alphasense Application Note AAN 105, To the Published Amplifier Circuits, ELECTRONICS AND COMMUNICATION, ELECTRONICS AND COMMUNICATION ENGINEERING UNIT, Application of Microwave GaAs FETs