LTC2262-12 Linear Dimensions Semiconductor, LTC2262-12 Datasheet - Page 13

• Manufacturer Part Number: LTC2262-12
• Description: 150Msps Ultralow Power 1.8V ADC
• Manufacturer: Linear Dimensions Semiconductor

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APPLICATIONS INFORMATION
CONVERTER OPERATION
The LTC2262-12 is a low power 12-bit 150Msps A/D
converter that is powered by a single 1.8V supply. The
analog inputs should be driven differentially. The encode
input can be driven differentially or single-ended for lower
power consumption. The digital outputs can be CMOS,
double data rate CMOS (to halve the number of output
lines), or double data rate LVDS (to reduce digital noise in
the system.) Many additional features can be chosen by
programming the mode control registers through a serial
SPI port. See the Serial Programming Mode section.
ANALOG INPUT
The analog input is a differential CMOS sample-and-hold
circuit (Figure 2). The inputs should be driven differentially
around a common mode voltage set by the V
FUNCTIONAL BLOCK DIAGRAM
SENSE
0.1μF
1μF
V
A
A
V
REF
IN
IN
CM
+
–
INPUT
REFERENCE
S/H
SELECT
RANGE
1.25V
V
DD
/2
REF
BUF
FIRST PIPELINED
ADC STAGE
DIFF
AMP
REF
SECOND PIPELINED
ADC STAGE
0.1μF
REFH
Figure 1. Functional Block Diagram
REFH
CM
2.2μF
0.1μF
output
REFL
THIRD PIPELINED
REFL
ADC STAGE
0.1μF
INTERNAL CLOCK SIGNALS
CLOCK/DUTY
ENC
CONTROL
CYCLE
+
ENC
–
FOURTH PIPELINED
ADC STAGE
ENC
ENC
A
A
IN
IN
PAR/SER
+
–
+
–
LTC2262-12
10Ω
10Ω
CS
REGISTERS
Figure 2. Equivalent Input Circuit
CONTROL
1.2V
1.2V
MODE
SCK
V
V
10k
10k
DD
DD
FIFTH PIPELINED
SDI
ADC STAGE
V
SDO
DD
C
1.8pF
C
1.8pF
PARASITIC
PARASITIC
AND CORRECTION
SHIFT REGISTER
DRIVERS
OUTPUT
LTC2262-12
OGND
25Ω
25Ω
R
R
ON
ON
226212 F01
C
C
SAMPLE
SAMPLE
3.5pF
3.5pF
•
•
•
226212 F02
OV
OF
D11
D0
CLKOUT
GND
CLKOUT
V
DD
DD
13
+
–
226212p