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Design self bias circuit using JFET for midpoint biasing. Let $I_{DSS}= 8mA, V_p= -3V$
1 Answer
| written 8.0 years ago by |
Step 1: Circuit Diagram

Step 2: Finding $I_{DSQ} and V_{GSQ}$
Since mid-point biasing is mentioned then,
$I_{DSQ}=\frac{1}{2}I_{DSS}=\frac{1}{2}\times8mA$
$I_{DSQ}=4mA$
We know that,
$I_{DSQ}=I_{DSS}(1-\frac {V_{GSQ}}{V_P})^2$
$4mA=8mA(1+\frac{V_{GSQ}}{3})^2$
$V_{GSQ}=-0.87V$
Step 3: Finding Rs
$V_{GS}=-I_{DSQ}\times R_s$
$-0.87=-4mA\times R_s$
$R_s=217.5\Omega$
Step 4: Finding Rd
Apply KVL from $V_{DD}$ to Ground,
$V_{DD}-I_{DSQ}(Rd+Rs)-V_{DSQ}=0$
Since mid point biasing is …