12

LT1306

0

1306 F06

AMOUNT OF

MIDBAND GAIN

NEEDED

GAIN

(dB)

1

1

R1 + R2

MIDBAND GAIN =

ˆ

ˆV

C

ˆ

ˆV

O

ω

CURRENT LOOP

CROSSOVER

FREQUENCY

OVERALL LOOP GAIN

AFTER COMPENSTION

AMPLITUDE RESPONSE

OF THE ERROR AMPLIFIER

AMPLITUDE RESPONSE OF

CONTROL-TO-OUTPUT

TRANSFER FUNCTION BEFORE

COMPENSATION

2

L

RHP ZERO

=

2

FREQUENCY

≈ 1

3

LOOP GAIN

CROSSOVER

Figure 6. Gain Asymptotes of the Control-to-Output

ˆ

ˆ

V

V

O

C











ˆ

ˆ

V

V

C

O











Figure 7. Current Mode Boost Converter Overall-Loop Compensation

L

1.24V

LT1306

1306 F07

PWM CONTROL

LOGIC

Q1

R1

FB

R2

R3

GND

Q2

RECTIFIER

SW