(a) Assuming ro @ RD, derive an expression for the short-circuit noise eni of the CS amplifi er of Fig. P7.83a (b) Find the open-circuit noise ini. (c) One might think that with two input sources...

(a) Assuming ro @ RD, derive an expression for the short-circuit noise eni of the CS amplifi er of Fig. P7.83a

(b) Find the open-circuit noise ini. (c) One might think that with two input sources noise is counted twice. To prove that this is not the case, refer to where R is assumed noiseless for simplicity. Prove that the combined power density e ng 2 at the gate is independent of R, indicating that for R → 0 only eni suffi ces, for R → ` only ini suffi ces, but for intermediate values of R both sources are necessary in order to make the output noise eno come out right. (In a practical circuit one would try to keep R suitably small to make its thermal noise contribution negligible).