1

LT5514

5514f

Ultralow Distortion IF

Amplifier/ADC Driver with

Digitally Controlled Gain

s

Output IP3 at 100MHz: 47dBm

s

Maximum Output Power: 21dBm

s

Bandwidth: LF to 850MHz

s

Propagation Delay: 0.8ns

s

Maximum Gain: 33dB

s

Noise Figure: 7.3dB (Max Gain)

s

Gain Control Range: 22.5dB

s

Gain Control Step: 1.5dB

s

Gain Control Settling Time: 500ns

s

Output Noise Floor: –134dBm/Hz (Max Gain)

s

Reverse Isolation: –80dB

s

Single Supply: 4.75V to 5.25V

s

Low Power Mode

s

Shutdown Mode

s

Enable/Disable Time: 1

µs

s

Differential I/O Interface

s

20-Lead TSSOP Package

s

High Linearity ADC Driver

s

IF Sampling Receivers

s

VGA IF Power Amplifier

s

50

Ω Driver

s

Instrumentation Applications

, LTC and LT are registered trademarks of Linear Technology Corporation.

DESCRIPTIO

FEATURES

APPLICATIO S

The LT

bandwidth extending from low frequency (LF) to 850MHz.

It consists of a digitally controlled variable attenuator,

followed by a high linearity amplifier. The amplifier is

configured with two identical transconductance amplifi-

ers, hard wired in parallel with individual dedicated enable

pins. When both amplifiers are enabled (Standard mode),

the LT5514 offers an OIP3 of +47dBm (at 100MHz).

Power dissipation can be reduced when a single amplifier

is enabled (Low Power mode). Four parallel digital inputs

control the gain over a 22.5dB range with 1.5dB step

resolution. An on-chip power supply regulator/filter helps

isolate the amplifier signal path from external noise sources.

The LT5514’s open-loop architecture offers stable opera-

tion for any practical load conditions, including peaking-

free AC response when driving capacitive loads, and

excellent reverse isolation.

The LT5514 may be operated broadband, where the out-

put differential RC time constant sets the bandwidth, or it

may be used as a narrowband driver with the appropriate

output filter.

TYPICAL APPLICATIO

FREQUENCY (MHz)

0

47

50

56

150

5514 TA02

44

41

50

100

200

38

35

53

LT5514

ADC

0.1

µF

0.1

µF

100

Ω

5V

CHOKE

GAIN CONTROL

CHOKE

0.1

µF

5514 TA01

0.1

µF

IF

AMP

IF

BPF

LO

RF

INPUT

4 LINES

Output IP3 vs Frequency

(Standard Mode)