LT5514_15 Datasheet, PDF (1/20 Pages) Linear Technology – Ultralow Distortion IF Amplifier/ADC Driver with Digitally Controlled Gain

FEATURES
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: 1µs}
s _{Differential I/O Interface}
s _{20-Lead TSSOP Package}
U
APPLICATIO S
s _{High Linearity ADC Driver}
s _{IF Sampling Receivers}
s _{VGA IF Power Amplifier}
s _{50Ω Driver}
s _{Instrumentation Applications}
LT5514
Ultralow Distortion IF
Amplifier/ADC Driver with
Digitally Controlled Gain
DESCRIPTIO
The LT^®5514 is a programmable gain amplifier (PGA) with
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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
0.1µF
CHOKE
5V
CHOKE
0.1µF
RF
INPUT
IF
IF
BPF AMP
LT5514
100Ω
LO
0.1µF
0.1µF
GAIN CONTROL
4 LINES
ADC
5514 TA01
Output IP3 vs Frequency
(Standard Mode)
56
53
50
R_OUT = 200Ω
47
R_OUT = 100Ω
44
41
38
35
0
50
100
150
FREQUENCY (MHz)
200
5514 TA02
5514f
1