LT1993-2_15 Datasheet, PDF (1/20 Pages) Linear Technology – 800MHz Low Distortion, Low Noise Differential Amplifier

FEATURES
■ _{800MHz –3dB Bandwidth}
■ _{Fixed Gain of 2V/V (6dB)}
■ _{Low Distortion:}
38dBm OIP3, –70dBc HD3 (70MHz, 2V_P-P)
51dBm OIP3, –94dBc HD3 (10MHz, 2V_P-P)
■ _{Low Noise: 12.3dB NF, en = 3.8nV/√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.
LT1993-2
800MHz Low Distortion, Low
Noise Differential Amplifier/
ADC Driver (A_V = 2V/V)
DESCRIPTIO
The LT^®1993-2 is a low distortion, low noise Differential
Amplifier/ADC driver for use in applications from DC to
800MHz. The LT1993-2 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
LT1993-2 an excellent solution for driving high speed 12-
bit and 14-bit ADCs. In addition to the normal unfiltered
outputs (+OUT and –OUT), the LT1993-2 has a built-in
175MHz differential low pass 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 LT1993-2 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 LT1993-2 can be used in data
acquisition systems required to function at frequencies
down to DC.
The LT1993-2 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
4-Channel WCDMA Receive Channel
70MHz
IF IN
1:4
0.1µF
Z-RATIO
0.1µF
MINI-CIRCUITS
TCM4-19
–INB
–OUT
–INA
–OUTFILTERED
LT1993-2
+OUTFILTERED
+INB
+OUT
+INA V_OCM
ENABLE
2.2V
12.2Ω
AIN–
82nH 52.3pF
LTC2255
ADC
AIN+
12.2Ω
LTC2255 125Msps
14-BIT ADC SAMPLING
AT 92.16Msps
19932 TA01a
4-Tone WCDMA Waveform,
LT1993-2 Driving LTC2255 14-Bit
ADC at 92.16Msps
0 _{32768 POINT FFT}
–10 _{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)
19932 TA01b
19932fa
1