9

LTC1550/LTC1551

noise – 4.1V generator which uses a ferrite bead output

ripple. The corresponding spectrum and spot noise plots

for this circuit are shown in the Typical Performance

Characteristics section.

Output Ripple vs Input Bypass Capacitor

of the LTC1550/LTC1551’s supply current while it is

charging the flying capacitor (C1). Inadequate input bypass

switches, causing the output linear regulator to momentarily

LTC1550/LTC1551 as possible and its value should be

significantly larger than C1. Tantalum capacitors with low

ESR generally provide adequate performance. Figure 6

shows the LTC1550/LTC1551 peak-to-peak output ripple

capacitor.

A 4.7

adequate output ripple performance for most applica-

tions.

– 4.1V Output GaAs FET Bias Generator

Figure 6. Output Ripple vs Input Bypass Capacitance

INPUT CAPACITANCE (

µF)

0.1

8

7

6

5

4

3

2

1

0

1

10

100

LTC1550/51 • F07

1

2

4.5V

8

7

SENSE

SHDN

LTC1550

– 4.1V BIAS

GND

10

µF

1550/51 TA02

0.1

µF

GaAs

TRANSMITTER

C1

0.1

µF

4.7

µF

3

4

6

5

0.1

µF

+