LT1993-4 Datasheet, PDF (1/16 Pages) Linear Technology – 900MHz Low Distortion, Low Noise Differential Amplifi er/ADC Driver (AV = 4V/V)

FEATURES
■ _{900MHz –3dB Bandwidth}
■ _{Fixed Gain of 4V/V (12dB)}
■ _{Low Distortion:}
40dBm OIP3, –73dBc HD3 (70MHz 2V_P-P)
51dBm OIP3, –94dBc HD3 (10MHz 2V_P-P)
■ _{Low Noise: 14.5dB NF, en = 2.35nV/√Hz (70MHz)}
■ _{Differential Inputs and Outputs}
■ _{Additional Filtered Outputs}
■ _{Adjustable Output Common Mode Voltage}
■ _{DC- or AC-Coupled Operation}
■ _{Minimal Support Circuitry Required}
■ _{Small 0.75mm Tall 16-Lead 3 × 3 QFN Package}
U
APPLICATIO S
■ _{Differential ADC Driver for:}
Imaging
Communications
■ _{Differential Driver/Receiver}
■ _{Single Ended to Differential Conversion}
■ _{Differential to Single Ended Conversion}
■ _{Level Shifting}
■ _{IF Sampling Receivers}
■ _{SAW Filter Interfacing/Buffering}
, LTC and LT are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
LT1993-4
900MHz Low Distortion, Low
Noise Differential Amplifier/
ADC Driver (A_V = 4V/V)
DESCRIPTIO
The LT^®1993-4 is a low distortion, low noise Differential
Amplifier/ADC driver for use in applications from DC to
900MHz. The LT1993-4 has been designed for ease of
use, with minimal support circuitry required. Exception-
ally low input-referred noise and low distortion products
(with either single-ended or differential inputs) make the
LT1993-4 an excellent solution for driving high speed 12-
bit and 14-bit ADCs. In addition to the normal unfiltered
outputs (+OUT and –OUT), the LT1993-4 has a built-in
175MHz differential lowpass filter and an additional pair
of filtered outputs (+OUTFILTERED, –OUTFILTERED) to
reduce external filtering components when driving high
speed ADCs. The output common mode voltage is easily set
via the V_OCM pin, eliminating either an output transformer
or AC-coupling capacitors in many applications.
The LT1993-4 is designed to meet the demanding require-
ments of communications transceiver applications. It can
be used as a differential ADC driver, a general-purpose
differential gain block, or in any other application requir-
ing differential drive. The LT1993-4 can be used in data
acquisition systems required to function at frequencies
down to DC.
The LT1993-4 operates on a 5V supply and consumes
100mA. It comes in a compact 16-lead 3 × 3 QFN package
and operates over a –40°C to 85°C temperature range.
TYPICAL APPLICATIO
ADC Driver with Single-Ended to Differential Conversion
70MHz
IF IN
1:1
0.1µF
Z-RATIO
100Ω
MA/COM
ETC1-1-13 ^0.1µF
–INB
–OUT
–INA
–OUTFILTERED
LT1993-4
+INB
+INA
+OUTFILTERED
+OUT
V_OCM
ENABLE
2.2V
12.2Ω
AIN–
82nH 52.3pF
LTC2255
ADC
12dB GAIN
AIN+
12.2Ω
LTC2255 125Msps
14-BIT ADC SAMPLING
AT 92.16Msps
19934 TA01
4-Tone WCDMA Waveform,
LT1993-4 Driving LTC2255
14-Bit ADC at 92.16Msps
0
–10
32768 POINT FFT
TONE CENTER FREQUENCIES
–20 _{AT 62.5MHz, 67.5MHz,}
–30 ^{72.5MHz, 77.5MHz}
–40
–50
–60
–70
–80
–90
–100
–110
–120
0
5 10 15 20 25 30 35 40 45
FREQUENCY (MHz)
LT19934 TA02
19934fa
1