1Course Outline
2. Chapter 3: Semiconductors
3. Chapter 4: Diodes
5. Chapter %: &ipolar 'unction "ransistors #&'"$
%. Chapter 2 #optional$: Operational Amplifiers
 
2
3 4.5 *ectifier Circuits
The primary application of diode is the rectifier –
Electrical device which converts alternating current (AC) to direct current (DC)
ne important application of rectifier is dc power supply!
 
4
 
 
step #3: employ low-pass lter to reduce wave amplitude by > !"
step #4: employ voltage regulator to eliminate ripple
step #5: supply dc load # 
 
54.5.1 "he ,alf-a/e *ectifier
,alf-0a/e rectifier –
sinusoid
EE 3110 Microelectronics I Suketu Naik
6 4.5.1 "he ,alf-a/e *ectifier
Small inputs  $egardless of the model employed% one should note that the rectifier will not operate properly  when input voltage is small (& 'V)
 
7 4.5.2 ull-a/e *ectifier
Center-tapping of the transformer allo0ing re/ersal
of certain currents
8
conducts 0hile D2 6loc7s
4.5.2. ull-a/e *ectifier
9
conducts 0hile D1 6loc7s
4.5.2 ull-a/e *ectifier
10 Center-tapped "ransformer
11
An alternative implementation of the full#wave rectifier is 6ridge rectifier
Does not reuire center#tapped transformer  our diodes instead of two
4.5.3 &ridge *ectifier
12
 D1 and D2 conduct 0hile D3 and D4 6loc7 
4.5.3 &ridge *ectifier
13
 D3 and D4 conduct 0hile D1 and D2 6loc7 
4.5.3 &ridge *ectifier
14 4.5.4. "he *ectifier 0ith a ilter Capacitor
 *hy is this e+ample unrealistic,  Because for any practical application%
the converter would supply a load
(which in turn provides a path for capacitor discharging)
 
15 4.5.4. "he *ectifier 0ith a ilter Capacitor
 
16
 
174.5.4. "he *ectifier 0ith a ilter Capacitor
(recision rectifier – is a device which facilitates
rectification of low#voltage input waveforms
-ow,
184.%: 8imiting and Clamping Circuits
9: *hat is a limiter or clamping circuit,
A: ne which limits voltage output!
 
19
20
soft vs! hard limiter    9: -ow are limiter circuits applied, A: /ignal processing%
used to prevent  .reakdown of transistors within various devices!
*hy use soft,
 
214.%.2 "he Clamped Capacitor or DC *estorer
9: *hat is a DC restorer, A: Circuit which provides the dc
component of an AC without DC value!
9: *hy is this a.ility important, A: 
') Average value of the output is effective way to measure duty cycle
 
22
dou6ler,
signal .y two!
23 4.; Special Diodes
Schott7<-&arrier Diode or
semiconductor 
on and off faster than p#n
 4unction
than p#n 4unction
24 4.; Special Diodes
reverse#.iased p#n 4unction  4unction capacitance is a
function of reverse .ias voltage how, voltage varia.le capacitor  tuning of receivers% 1hase
locked loops
Anode Cathode
25
(hotodiodes
reverse#.iased p#n 4unction e+pose to light3 covalent .onds  .reak% electron#hole pairs are created
free electrons sweep to n side and holes to p side
reverse current is created  photocurrent is proportational to
intensity of incident light convert light into electric signal applications3 CD#$2% fi.er#optic what happens when you don9t
reverse .ias the photodiode and e+pose it to light,
4.; Special Diodes
264.; Special Diodes
convert forward current into light forward .ias region3 when minority
carriers diffuse into p and n sides% they recom.ine with ma4ority carriers% e!g! electrons with holes!
recom.ination3 emission of light special semiconductor material3
direct .and#gap known spectra of light when
electrons leave or.it emitted light is proportional to
num.er of recom.inations which is  proportional to the forward current
Anode Cathode