Equations

Question 1

What is the formula for thermal voltage $V_T$?

Answer 1

$V_T = rac{kT}{q}$

Question 2

What is the value of thermal voltage $V_T$ at 28.6°C?

Answer 2

$V_T(28.6^circ C) = 26 , mV$

Question 3

What is the equation for the diode current $i_D(t)$?

Answer 3

$i_D(t) = I_S e^{v_D(t) / n V_T}$

Question 4

What is the equation for the diode voltage $v_D(t)$?

Answer 4

$v_D(t) = n V_T lnleft( rac{i_D(t)}{I_S}
ight)$

Question 5

What is the small-signal resistance $r_D$ of a diode?

Answer 5

$r_D = rac{n V_T}{I_{DQ}}$

Question 6

What is the formula for rectifier ripple voltage $Delta V$?

Answer 6

$Delta V = rac{V_M cdot T_P}{R cdot C}$, where $T_P$ is the repeating period

Question 7

What is the relationship for peak current in a rectifier?

Answer 7

$V_o I_o approx rac{1}{2} x V_{in,pk} I_{pk}$, where $x$ is the fraction of a period where the capacitor is charging

Question 8

What are the conditions for the nonsaturation (triode) region in an N-channel MOSFET?

Answer 8

$v_{DS} < v_{GS} - V_{TN}$ and $v_{GS} > V_{TN}$

Question 9

What is the drain current equation $i_D$ in the nonsaturation (triode) region for an N-channel MOSFET?

Answer 9

$i_D = K_n [2(v_{GS} - V_{TN}) v_{DS} - v_{DS}^2]$

Question 10

What are the conditions for the saturation (linear) region in an N-channel MOSFET?

Answer 10

$v_{DS} > v_{GS} - V_{TN}$ and $v_{GS} > V_{TN}$

Question 11

What is the drain current equation $i_D$ in the saturation (linear) region for an N-channel MOSFET?

Answer 11

$i_D = K_n (v_{GS} - V_{TN})^2$

Question 12

What is the threshold voltage sign for enhancement mode in N-channel MOSFETs?

Answer 12

Enhancement Mode: $V_{TN} > 0$

Question 13

What is the threshold voltage sign for depletion mode in N-channel MOSFETs?

Answer 13

Depletion Mode: $V_{TN} < 0$

Question 14

What is the formula for the conduction parameter $K_n$ in N-channel MOSFETs?

Answer 14

$K_n = k_n’ rac{W}{2L}$

Question 15

What are the conditions for the nonsaturation (triode) region in a P-channel MOSFET?

Answer 15

$v_{SD} < v_{SG} + V_{TP}$ and $v_{SG} > -V_{TP}$

Question 16

What is the drain current equation $i_D$ in the nonsaturation (triode) region for a P-channel MOSFET?

Answer 16

$i_D = K_p [2(v_{SG} + V_{TP}) v_{SD} - v_{SD}^2]$

Question 17

What are the conditions for the saturation (linear) region in a P-channel MOSFET?

Answer 17

$v_{SD} > v_{SG} + V_{TP}$ and $v_{SG} > -V_{TP}$

Question 18

What is the drain current equation $i_D$ in the saturation (linear) region for a P-channel MOSFET?

Answer 18

$i_D = K_p (v_{SG} + V_{TP})^2$

Question 19

What is the threshold voltage sign for enhancement mode in P-channel MOSFETs?

Answer 19

Enhancement Mode: $V_{TP} < 0$

Question 20

What is the threshold voltage sign for depletion mode in P-channel MOSFETs?

Answer 20

Depletion Mode: $V_{TP} > 0$

Question 21

What is the formula for the conduction parameter $K_p$ in P-channel MOSFETs?

Answer 21

$K_p = k_p’ rac{W}{2L}$

Question 22

What is the first expression for transconductance $g_m$ in an NMOS transistor?

Answer 22

$g_m = 2 K_n (V_{GSQ} - V_{TN})$

Question 23

What is the second expression for transconductance $g_m$ in an NMOS transistor?

Answer 23

$g_m = 2 sqrt{K_n I_{DQ}}$