LT1259IN 查看數據表（PDF） - Linear Technology

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LT1259IN

Low Cost Dual and Triple 130MHz Current Feedback Amplifiers with Shutdown

Linear Technology 

APPLICATIO S I FOR ATIO

Amplifier Disable Time, AV = 10

EN

LT1259/LT1260

Amplifier Enable/Disable Time, AV = 2

EN

OUTPUT

OUTPUT

VS = ±5V RF = 1k

RL = 150Ω

VIN = 0.1V RG = 110Ω

LT1259/LT1260 • AI05

VS = ±5V

RF = RG = 1.6k

VIN = 2VPP at 2MHz RL = 100Ω

LT1259/LT1260 • AI06

Differential Input Signal Swing

The differential input swing is limited to about ±6V by an

ESD protection device connected between the inputs. In

normal operation, the differential voltage between the

input pins is small, so this clamp has no effect. In the

disabled mode however, the differential swing can be the

same as the input swing, and the clamp voltage will set the

maximum allowable input voltage.

TYPICAL APPLICATIO S

2-Input Video MUX Cable Driver

The application on the first page shows a low cost, 2-

input video MUX cable driver. The scope photo displays

the cable output of a 30MHz square wave driving 150Ω.

In this circuit the active amplifier is loaded by RF and RG

of the disabled amplifier, but in this case it only causes a

1.2% gain error. The gain error can be eliminated by

2-Input Video MUX Switching Response

EN A

EN B

VS = ±5V

RF = RG = 1.6k

VIN A = VIN 2 = 2VPP at 2MHz RL = 100Ω

LT1259/LT1260 • TA03

configuring each amplifier as a unity-gain follower. The

switching time between channels is 100ns when both

EN A and EN B are driven.

2-Input RGB MUX Cable Driver Demonstration Board

A complete 2-input RGB MUX has been fabricated on PC

Demo Board #039A. The board incorporates two LT1260s

with outputs summed through 75Ω back termination

resistors as shown in the schematic. There are several

things to note about Demo Board #039A:

1. The feedback resistors of the disabled LT1260 load

the enabled amplifier and cause a small (1% to 2%)

gain error depending on the values of RF and RG.

Configure the amplifiers as unity-gain followers to

eliminate this error.

2. The feedback node has minimum trace length connect-

ing RF and RG to minimize stray capacitance.

3. Ground plane is pulled away from RF and RG on both

sides of the board to minimize stray capacitance.

9

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