pc200 lectures - wilfrid laurier university
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CapacitorsDiodes
Transistors
PC200 Lectures
Terry Sturtevant
Wilfrid Laurier University
June 4, 2009
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Capacitor
an electronic device which consists of two conductive platesseparated by an insulator
value, capacitance, is proportional to the surface area of theplates and inversely proportional to the distance between theplates
measured in Farads
Farads are big
usually microfarad (µF) or picofarad (pF) values are used
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Capacitor
an electronic device which consists of two conductive platesseparated by an insulator
value, capacitance, is proportional to the surface area of theplates and inversely proportional to the distance between theplates
measured in Farads
Farads are big
usually microfarad (µF) or picofarad (pF) values are used
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Capacitor
an electronic device which consists of two conductive platesseparated by an insulator
value, capacitance, is proportional to the surface area of theplates and inversely proportional to the distance between theplates
measured in Farads
Farads are big
usually microfarad (µF) or picofarad (pF) values are used
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Capacitor
an electronic device which consists of two conductive platesseparated by an insulator
value, capacitance, is proportional to the surface area of theplates and inversely proportional to the distance between theplates
measured in Farads
Farads are big
usually microfarad (µF) or picofarad (pF) values are used
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Capacitor
an electronic device which consists of two conductive platesseparated by an insulator
value, capacitance, is proportional to the surface area of theplates and inversely proportional to the distance between theplates
measured in Farads
Farads are big
usually microfarad (µF) or picofarad (pF) values are used
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Capacitor uncharged
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Capacitor charging; charge on opposite plates is equal and opposite.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Capacitor charging; charge on opposite plates is equal and opposite.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Capacitor charged; no more change
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
purpose is to store electrical charge.
current starts large, voltage starts at zero
as charge is stored, voltage increases and current decreasesuntil the voltage equals the applied voltage, when currentbecomes zero
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
purpose is to store electrical charge.
current starts large, voltage starts at zero
as charge is stored, voltage increases and current decreasesuntil the voltage equals the applied voltage, when currentbecomes zero
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
purpose is to store electrical charge.
current starts large, voltage starts at zero
as charge is stored, voltage increases and current decreasesuntil the voltage equals the applied voltage, when currentbecomes zero
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
A capacitor’s voltage may not exceed the maximum for whichit is rated. Big capacitors often have low maximumvoltages.
Capacitors may retain charge long after power is removed.
For safety, large capacitors should be discharged beforehandling.
Place 1kΩ → 1kΩ resistor across the terminals to discharge.
High voltage capacitors should be stored with terminalsshorted.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
A capacitor’s voltage may not exceed the maximum for whichit is rated. Big capacitors often have low maximumvoltages.
Capacitors may retain charge long after power is removed.
For safety, large capacitors should be discharged beforehandling.
Place 1kΩ → 1kΩ resistor across the terminals to discharge.
High voltage capacitors should be stored with terminalsshorted.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
A capacitor’s voltage may not exceed the maximum for whichit is rated. Big capacitors often have low maximumvoltages.
Capacitors may retain charge long after power is removed.
For safety, large capacitors should be discharged beforehandling.
Place 1kΩ → 1kΩ resistor across the terminals to discharge.
High voltage capacitors should be stored with terminalsshorted.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
A capacitor’s voltage may not exceed the maximum for whichit is rated. Big capacitors often have low maximumvoltages.
Capacitors may retain charge long after power is removed.
For safety, large capacitors should be discharged beforehandling.
Place 1kΩ → 1kΩ resistor across the terminals to discharge.
High voltage capacitors should be stored with terminalsshorted.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
A capacitor’s voltage may not exceed the maximum for whichit is rated. Big capacitors often have low maximumvoltages.
Capacitors may retain charge long after power is removed.
For safety, large capacitors should be discharged beforehandling.
Place 1kΩ → 1kΩ resistor across the terminals to discharge.
High voltage capacitors should be stored with terminalsshorted.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
I = 0
Vs
R
Q = 0 Vc = 0
t = 0, switch open
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
I = Vs/R
Vs
R
Q = 0 Vc = 0
t = 0, switch closed
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
I < Vs/R
Vs
R
Q > 0 Vs > Vc > 0
t ≈ RC
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
I = 0
Vs
R
Q = CVs Vc = Vs
t >> RC
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Some capacitiors are unpolarized (like resistors);
i.e. they can be placed either way in a circuit.
Other types, (such as ”electrolytics”), must be placed in aparticular direction
(indicated by a ”+” sign at one end.)
Big capacitors (& 1µF ) are usually electrolytic.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Some capacitiors are unpolarized (like resistors);
i.e. they can be placed either way in a circuit.
Other types, (such as ”electrolytics”), must be placed in aparticular direction
(indicated by a ”+” sign at one end.)
Big capacitors (& 1µF ) are usually electrolytic.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Some capacitiors are unpolarized (like resistors);
i.e. they can be placed either way in a circuit.
Other types, (such as ”electrolytics”), must be placed in aparticular direction
(indicated by a ”+” sign at one end.)
Big capacitors (& 1µF ) are usually electrolytic.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Some capacitiors are unpolarized (like resistors);
i.e. they can be placed either way in a circuit.
Other types, (such as ”electrolytics”), must be placed in aparticular direction
(indicated by a ”+” sign at one end.)
Big capacitors (& 1µF ) are usually electrolytic.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Some capacitiors are unpolarized (like resistors);
i.e. they can be placed either way in a circuit.
Other types, (such as ”electrolytics”), must be placed in aparticular direction
(indicated by a ”+” sign at one end.)
Big capacitors (& 1µF ) are usually electrolytic.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Non-polarized capacitor
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Polarized capacitor connected the right way
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Polarized capacitor connected the wrong way
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Don’t do this!!!
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
Diode
an electronic device which passes current in one direction only
diode starts to allow current in the forward direction when thevoltage reaches around 0.6V
If the voltage gets high enough in the reverse direction, thediode will conduct; “reverse breakdown voltage”
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
Diode
an electronic device which passes current in one direction only
diode starts to allow current in the forward direction when thevoltage reaches around 0.6V
If the voltage gets high enough in the reverse direction, thediode will conduct; “reverse breakdown voltage”
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
Diode
an electronic device which passes current in one direction only
diode starts to allow current in the forward direction when thevoltage reaches around 0.6V
If the voltage gets high enough in the reverse direction, thediode will conduct; “reverse breakdown voltage”
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
Negative pressure; no flow possible
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
No pressure; resistance to flow is large
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
Small pressure; resistance to flow decreases
-
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
Medium pressure; resistance to flow still decreasing
--
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
High pressure; resistance to flow small
---
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
Very high pressure; resistance almost zero
----
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
+ -
Diode symbol and physical appearance
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
“off”
V . 0.7?
“off”
I small; changes slowly
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
“off”
V ≈ 0.7
6 “on”
I large; almost independent of V
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
forward biasreversebreakdown
|V | < Vz
6
I small; changes slowly
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
forward biasreversebreakdown
Vz 6
I large; almost independent of V
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
VD ≈ 0.7
Vo ≈ Vs − 0.7
(assuming Vs & 0.7)
Vs
Forward biased diode in a voltage divider
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
VD ≈ 0.7
Vo ≈ 0.7
(assuming Vs & 0.7)
Vs
Forward biased diode in a voltage divider
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
Vo ≈ Vs
(assuming Vs > 0)
I ≈ 0
Vs
Reverse biased diode in a voltage divider
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
Vo ≈ 0
(assuming Vs > 0)
I ≈ 0
Vs
Reverse biased diode in a voltage divider
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
LEDs are a special case; they light up above a certain voltage. Thevoltage depends on the colour.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
anode (+) cathode (-)
The LED lights up when current flows from the anode to thecathode..
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
You must use a resistor to limit the current.
Without a resistor, the LED will probably be destroyed.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
The resistor can go before or after the LED.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
The resistor can go before or after the LED.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
Reverse-biased, the LED won’t light up.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
TransistorsLEDs
Reverse-biased, the LED won’t light up.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
There are several types of transistor; each is a three terminaldevice.
The most common types of transistors are BJTs and FETs.
Transistors are often used in voltage dividers to act as variableresistors.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
There are several types of transistor; each is a three terminaldevice.
The most common types of transistors are BJTs and FETs.
Transistors are often used in voltage dividers to act as variableresistors.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
There are several types of transistor; each is a three terminaldevice.
The most common types of transistors are BJTs and FETs.
Transistors are often used in voltage dividers to act as variableresistors.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
collector
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
collector
emitter
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
collector
emitterbase
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
Vs
Ic ≈ 0 if Vi . 0.7
Vo ≈ Vs if Vi . 0.7Vi . 0.7
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
Vs
Ic ≈ 0 if Vi . 0.7
Vo ≈ Vs if Vi . 0.7Vi . 0.7
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
Vs
Ic ∝ Ib if Vi > 0.7
Vo = Vs − IcR if Vi > 0.7Vi > 0.7
≈ 0.7
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
BJTS are current amplifiers; a small base current controls amuch larger collector/emitter current.
You should always have a base resistor with a BJT!
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
BJTS are current amplifiers; a small base current controls amuch larger collector/emitter current.
You should always have a base resistor with a BJT!
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
FETS are voltage amplifiers; a small gate voltage controls amuch larger drain/source current.
Actually it’s the voltage between the gate and the source whichmatters.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
drain
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
drain
source
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
drain
sourcegate
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
Vsupply
Vo
I ≈ 0 if Vgs . Vgson
Vgs
E (ehancement mode) FET
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
Vsupply
Vo = VDS
Vgs
E (ehancement mode) FET
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
Vsupply
Vo ≈ Vsupply if Vgs < Vgson
Vgs = 0
gate
E (ehancement mode) FET
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
Vsupply
Vo = VDS > 0 if Vgs & Vgson
Vgs & Vgson
gate
E (ehancement mode) FET
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
Vsupply
Vo = VDS → 0 if Vgs >> Vgson
Vgs >> Vgson
gate
E (ehancement mode) FET
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
FETS are voltage amplifiers; a small gate-source voltagecontrols a much larger drain/source current.
You do not use a gate resistor with an FET!
All FETs work in enhancement mode; some also work indepletion mode.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
FETS are voltage amplifiers; a small gate-source voltagecontrols a much larger drain/source current.
You do not use a gate resistor with an FET!
All FETs work in enhancement mode; some also work indepletion mode.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
FETS are voltage amplifiers; a small gate-source voltagecontrols a much larger drain/source current.
You do not use a gate resistor with an FET!
All FETs work in enhancement mode; some also work indepletion mode.
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
Vsupply
Vo = VDS > 0 if Vgs = 0
Vgs = 0
gate
D (depletion mode) FET
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
Vsupply
Vo
I ≈ 0 if Vgs . Vth < 0
Vgs has to be negative to turn off.Xy
Vgs
D (depletion mode) FET
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
Vsupply
Vo = VDS ≈ 0 if Vgs >> 0
Vgs
D (depletion mode) FET
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
Vsupply
Vo = VDS > 0 if Vgs & 0
Vgs & 0
gate
D (depletion mode) FET
Terry Sturtevant PC200 Lectures
CapacitorsDiodes
Transistors
Bipolar Junction TransistorsField Effect Transistors
Vsupply
Vo = VDS → 0 if Vgs >> 0
Vgs >> 0
gate
D (depletion mode) FET
Terry Sturtevant PC200 Lectures
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