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Linear Exam - MOSFET's

Steven Pearson Linear Electronics level 5 Inglés 32 fichas

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1how many types of active devices are there? what are they called?2
mosfet and BJT
21) Draw the structure of a MOSFET 2) Draw the symbols for the two types of MOSFETstructure --- symbols - pMOS & nMOS
31) Draw the structure for a BJT 2) Draw the symbols for the two types of BJT'sstructure --- symbols - NPN & PNP
4what does MOSFET stand for?Metal
Oxide
Silicon
Field
Effect
Transistor
51) How many operation regions are there for BJT and MOSFET and what are they called? 2) Draw The output characteristicsThere are 3 regions
Triode
Active
Off
6Draw the equivalent band model for a MOSFET device at mid-band frequency
7Draw the equivalent band model for a BJT device at mid-band frequency
8With the aid of the MOSFET’s structure, explain the origin of the parasitic capacitor. At what operating conditions will these capacitors start to play an important role, why?When at high frequency, these parasitic capacitors become important,
because these capacitors are very small.
Z = 1/(2*pi*f*C)
9With the aid of the BJT's structure, explain the origin of the parasitic capacitor. At what operating conditions will these capacitors start to play an important role, why?????
10Draw the equivalent band model for a MOSFET device at high-band frequency??
11Draw the equivalent band model for a BJT device at high-band frequency??
12list the Major differences between MOSFET and BJT1) BJT is three terminal device, while MOSFET is four terminal device.
2) BJT is a current-controlled device where the collector or emitter output is a
function of the current in the base. MOSFET is a voltage-controlled device.
There is no base current present.
3)The input of a typical BJT has a pn junction, while for MOSFETs, they are
insulated.
13what is also known as a DC Bias Point and what is it used forThe Q-point
Its used to set a mosfet in its saturation region for signal amplification
14what is the equation for Id current of a MOSFET whilst in the active region?Id = K*( Vg-Vt )^2
15how do you double check that the MOSFET is in the Active reigion?Vd: Vdd - Id * Rd
ensure that this value is greater than Vt (the threshold voltage)
16what is the equation for calculating RD over a mosfet?RD = ( VDD - VD ) / ID
17—
18how do you add coupling capacitors in to this circuit? and what is the function of them?AC ==> DC
19what is the equation for calculating Impedance ( Z ) ? + rearrange this equation to find frequency ( F ) ?Z = 1 / (2 * PI * F * C)
F = 1 / ( 2 * PI * C * Z
20—
21convert this circuit to its ac equivalent + what are the golden rules?
22how do you check the circuit is really equivalent?
23how do you calculate resistors in parallel? eg: R1 & R2R1 x R2 / (R1 + R2)
24Draw equivalent circuit at high-band.
25what does A stand for?A stands for voltage gain
26how is GM calculated over a mosfet AC equivalent circuit? - the equationGM= -A / Rd
gm is calculated by -gain / Rd
27what is the equation for calculating gain (A) over a mosfet device?A = -gm x Rd
or
A = Vout / Vin
28what is the formula for GM when gm and A are not given?GM = 2K * ( vg - vt )
29—
30how is Rin calcualted?Rin = Vin / Iin
31what is the formula for critical frequency?f = 1/ 2 * PI * R * C
32what is a bypass capacitor and what is are coupling capacitors?Bpass - used to force signal around elements by providing a low impedance path.
Coupling - used to decouple ac and dc signals which do not disturb the Qpoint.