## Lecture 24 and 25 :- Noise

Common Data : VDD = 1.8V , Lmin  = 0.18µm, µ0N = 350cm2/V s, µ0P  = 100cm2/V s, |VTH | = 0.55, tox = 3.8nm, λ = 0.07V−1, χ = 0.1.

1.Consider circuits shown in Fig.  33.  Which of these source degenerated circuits have higher input referred noise voltage, and by what factor? Figure 33 :  Source Degenerated Circuits

2. Design circuit in Fig. 34 for an input referred thermal noise voltage of and maximum output swing. Assume and  Figure 34: Common Gate Stage

3. The circuit in Fig. 35 is designed with and If an output swing of is required, estimate the dimension of and such that the input referred thermal noise current is minimum . Figure 35: Common Gate Stage

4. Assume Fig. 36. If the contribution of to the input referred noise voltage must be one-fifth of that of , what is the maximum output voltage swing of the amplifier? Figure 36 : (a) Common Source Amplifier (b) Source Follower

5. Consider the circuit of Fig. 37 - Fig. 38. To decrease overall noise of circuit,

1. Whether transconductance of should be kept high or low in two cases of Fig. 37? Figure 37 : (a) Common Source Amplifier (b) Inverter

1. Whether should be minimized to reduce noise in Fig. 38? Figure 38 : Source Degenerated Stage

6. Consider input stage of op-amp shown in Fig. 39,

1. Should transconductance of be decreased to decrease input-referred thermal noise?
2. How sizing of and should be done to reduce flicker noise? Figure 37 : (a) Common Source Amplifier (b) Inverter