Sam PalermoAnalog & Mixed-Signal Center

Texas A&M University

ECEN325: ElectronicsSpring 2014

Diode Rectifier Circuits

Rectifier Circuits

[Karsilayan]

2

Half-Wave Rectifier

[Karsilayan]

3

Half-Wave Rectifier Transfer Characteristic

[Karsilayan]

[Sedra/Smith]

• Only rectifies positive half of the input signal• Lose one diode voltage drop from the peak value

4

Half-Wave Rectifier w/ a Filter Cap

[Karsilayan]

( )( )

( ) RCt

poRCt

p

s

o eVtVttttt

eV

VtVtV

1

11

21

0,,7.0 −

− =

⇒<<<<−

=

5

Half-Wave Rectifier w/ a Filter Cap[Karsilayan]

6

Half-Wave Rectifier w/ a Filter Cap[Karsilayan]

7

Half-Wave Rectifier w/ a Filter Cap[Karsilayan]

RV

I pR ≈

8

Half-Wave Rectifier w/ a Filter Cap[Karsilayan]

(assuming a triangular capacitive current profile)

9

Full-Wave Rectifier

VVPIV s 7.0ˆ2 −=

[Sedra/Smith]

• Positive ½ cycle• Top diode on

• Negative ½ cycle• Bottom diode on

[Karsilayan]

10

Full-Wave Rectifier Transfer Characteristic

[Karsilayan]

[Sedra/Smith]

• Rectifies all of the input signal• Lose one diode voltage drop from the peak value

11

Bridge Rectifier

[Karsilayan]

VVPIV s 7.0ˆ −=

[Sedra/Smith]

• Positive ½ cycle• D1 & D3 on

• Negative ½ cycle• D2 & D4 on

-0.7V

Vs-0.7V-0.7V

Vs-0.7V

12

Bridge Rectifier Transfer Characteristic

• Rectifies all of the input signal• Lose two diode voltage drops from the peak value

[Karsilayan]

13

Full-Wave & Bridge Rectifier w/ a Filter Cap

[Sedra/Smith]

• The capacitor only discharges for T/2• Results in ½ Cap size for a given ripple• Roughly ½ diode current

LLpr CR

TVV2

=

+=

r

pRDavg V

VII

21 π

+=

r

pRD V

VII

221max π

14

Rectifier Trade-Offs

• Half-Wave Rectifier+Simplest design with fewest components- Requires largest capacitor for a given ripple

• Full-Wave Rectifier+Reduces capacitor size by ½ relative to half-wave- Requires center-tapped transformer- PIV almost double that of half-wave

• Bridge Rectifier+Reduces capacitor size by ½ relative to half-wave+Save PIV as half-wave rectifier- Lose two diode voltage drops in peak value

15