LTC1745 Datasheet, PDF (1/20 Pages) Linear Technology – Low Noise,12-Bit, 25Msps ADC

LTC1745
Low Noise,12-Bit, 25Msps ADC
FEATURES
s _{Sample Rate: 25Msps}
s _{72.5dB SNR and 91dB SFDR (3.2V Range)}
s _{71dB SNR and 96dB SFDR (2V Range)}
s _{No Missing Codes}
s _{Single 5V Supply}
s _{Low Power Dissipation: 380mW}
s _{Selectable Input Ranges: ±1V or ±1.6V}
s _{240MHz Full Power Bandwidth S/H}
s _{Pin Compatible Family}
25 Msps: LTC1746 (14-Bit), LTC1745 (12-Bit)
50 Msps: LTC1744 (14-Bit), LTC1743 (12-Bit)
65 Msps: LTC1742 (14-Bit), LTC1741 (12-Bit)
80 Msps: LTC1748 (14-Bit), LTC1747 (12-Bit)
U
APPLICATIO S
s _{Telecommunications}
s _{Medical Imaging}
s _Receivers
s _{Base Stations}
s _{Spectrum Analysis}
s _{Imaging Systems}
, LTC and LT are registered trademarks of Linear Technology Corporation.
DESCRIPTIO
The LTC^®1745 is a 25Msps, sampling 12-bit A/D con-
verter designed for digitizing high frequency, wide dy-
namic range signals. Pin selectable input ranges of ±1V
and ±1.6V along with a resistor programmable mode
allow the LTC1745’s input range to be optimized for a wide
variety of applications.
The LTC1745 is perfect for demanding communications
applications with AC performance that includes 72.5dB
SNR and 91dB spurious free dynamic range. Ultralow jitter
of 0.3ps_RMS allows undersampling with excellent noise
performance. DC specs include ±1LSB INL maximum and
±0.75LSB DNL over temperature.
The digital interface is compatible with 5V, 3V and 2V logic
systems. The ENC and ENC inputs may be driven differen-
tially from PECL, GTL and other low swing logic families or
from single-ended TTL or CMOS. The low noise, high gain
ENC and ENC inputs may also be driven by a sinusoidal
signal without degrading performance. A separate digital
output power supply can be operated from 0.5V to 5V,
making it easy to connect directly to low voltage DSPs
or FIFOs.
The TSSOP package with a flow-through pinout simplifies
the board layout.
BLOCK DIAGRA
A_IN+
±1V
DIFFERENTIAL
ANALOG INPUT _AIN–
SENSE
V_CM
4.7µF
RANGE
SELECT
2.35V_REF
25Msps, 12-Bit ADC with a ±1V Differential Input Range
S/H
12-BIT
AMP
PIPELINED ADC
12
OUTPUT
LATCHES
BUFFER
DIFF AMP
OV_DD
OF
•••
D11
D0
CLKOUT
0.1µF
OGND
V_DD
1µF
1µF
GND
CONTROL LOGIC
REFLB
0.1µF
1µF
REFHA
4.7µF
REFLA REFHB ENC ENC MSBINV
0.1µF DIFFERENTIAL
1µF
ENCODE INPUT
1745 BD
OE
0.5V TO 5V
0.1µF
5V
1µF
1745f
1