# hw12_sol - ECE ECE342 HW#12 Solutions 442 HW#13 Solutions 1...

This preview shows pages 1–4. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ECE ECE342 HW#12 Solutions 442 HW#13 Solutions 1. gm1 = gm1 VOV 1m × 0.2 2ID ⇒ ID = = = 100µA VOV 2 2 RO = (gm2 ro2 )ro1 Since the transistors are identical with the same current ﬂowing through both, ro1 = ro2 = ro and gm1 = gm2 = gm ; as speciﬁed in the problem: 2 RO = gm ro = 400k Ω ⇒ ro = 20k Ω Since ro = VA L ID , we have: L= gm = 2µn Cox W × L 100µ × 20k ID ro = = 0.4µm 1 VA 5µ ID ⇒ 2 W gm (1000µ)2 = = 12.5 = L 2µn Cox ID 2(400µ)(100µ) For the maximum negative swing at the output, we want the MOSFETs to be biased so that each transistor can reach VDS = VOV = 0.2V . ⇒ VG2 = Vtn + VOV + VOV = 0.5 + 0.2 + 0.2 = 0.9V Minimum output voltage will then be Vout = 2VOV = 0.4V . 2. From the small-signal schematic, we can write the following KCL equations, noting that the transistor M1 reduces to just a resistance ro1 , since the control voltage vgs1 = 0, and the control voltage vgs2 = 0−vy = −vy : ix = −(gm2 + gmb2 )vy + ⇒ vx − vy vy = ro2 ro1 ro1 1 vy ro1 ≈ ≈ = vx ro2 (1 + (gm2 + gmb2 )ro1 ) ro1 ro2 (gm2 + gmb2 ) gm2 ro2 Therefore, vy is smaller than vx by a factor of gm2 · ro2 . 3. a) For the same I in cases (a) and (b): I= gm ( W )a V2 1W2 L kn VOV ⇒ OV b = W 2 2 L VOV a ( L )b 2 For the same I, if W/L is divided by 4, then VOV is multiplied by 4, or equivalently VOV is doubled, W = µn Cox L VOV . Thus, gm for the circuit (b) is half of the one for circuit (a). AO = gm ro = 2ID VA 2V L × =A VOV ID VOV Thus, if L is multiplied by 4, and VOV is halved, then AO is doubled for circuit (b). In summary, for circuit (b), VOV is doubled, gm is halved, AO is doubled. 1 P6. ...
View Full Document

{[ snackBarMessage ]}

### Page1 / 4

hw12_sol - ECE ECE342 HW#12 Solutions 442 HW#13 Solutions 1...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online