LTC6420-20_15 Datasheet, PDF (1/14 Pages) Linear Technology – Dual Matched 1.8GHz Differential Amplifi ers/ADC Drivers

FEATURES
n _{Matched Gain ±0.1dB}
n _{Matched Phase ±0.1° at 100MHz}
n _{Channel Separation 80dB at 100MHz}
n _{1.8GHz –3dB Bandwidth; Fixed Gain of 10V/V (20dB)}
n _{IMD3 = –84dBc at 100MHz, 2VP-P}
n _{Equivalent OIP3 = 46dBm at 100MHz}
n _{1nV/√Hz Internal Op Amp Noise}
n _{6.2dB Noise Figure}
n _{Differential Inputs and Outputs}
n _{Rail-to-Rail Output Swing}
n _{80mA Supply Current (240mW) per Amplifier}
n _{1.1V to 1.6V Output Common Mode Voltage,}
Adjustable
n _{DC- or AC-Coupled Operation}
n _{20-Lead 3mm × 4mm × 0.75mm QFN Package}
APPLICATIONS
n _{Differential ADC Driver}
n _{Single Ended to Differential Conversion}
n _{IF Sampling (Diversity) Receivers}
n _{Broadband I/Q Amplifiers}
n _{Satellite Communications}
LTC6420-20
Dual Matched
1.8GHz Differential
Amplifiers/ADC Drivers
DESCRIPTION
The LTC^®6420-20 is a dual high-speed differential amplifier
targeted at processing signals from DC to 300MHz. The
part has been specifically designed to drive 12-, 14- and
16-bit ADCs with low noise and low distortion, but can also
be used as a general-purpose broadband gain block.
The LTC6420-20 is easy to use, with minimal support
circuitry required. The output common mode voltage
is set using an external pin, independent of the inputs,
which eliminates the need for transformers or AC-coupling
capacitors in many applications. The gain is internally
fixed at 20dB (10V/V).
The LTC6420-20 saves space and power compared to
alternative solutions using IF gain blocks and transformers.
The LTC6420-20 is packaged in a compact 20-lead
3mm × 4mm QFN package and operates over the –40°C
to 85°C temperature range.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
Matched Dual Amplifier with Output Common Mode Biasing
0.1μF ^3V 1000pF
V_OCM A
V_IN A
V_IN B
Z_IN = 200Ω
V+ A
0.1μF
–IN A
100Ω
0.1μF
+IN A
100Ω
V_OCM A
1000Ω
–
+
1000Ω
V–
LTC6420-20 _1000Ω
0.1μF
+IN B ^100Ω
+
0.1μF
–IN B ^100Ω
–
Z_IN = 200Ω
V+ B
0.1μF 1000pF
1000Ω
V_OCM B
V_OCM B
ENABLEA
12.5Ω
12.5Ω
12.5Ω
12.5Ω
ENABLEB
+OUT A
V_OCM A
–OUT A
V_OCM A
V–
±0.1dB GAIN MATCHING
±0.1° PHASE MATCHING AT 100MHz
– OUT B
+OUT B
V_OCM B
V_OCM B
642020 TA01a
3V
Distribution of Gain Match
40
35
30
25
20
15
10
5
0
– 0.25 – 0.15 – 0.05 0.05 0.15 0.25
CHANNEL-TO-CHANNEL GAIN MATCH (dB)
642020 TA01b
642020fb
1