LTC2209IUP#PBF Linear Technology, LTC2209IUP#PBF Datasheet - Page 20

• Manufacturer Part Number: LTC2209IUP#PBF
• Description: IC ADC 16BIT 160MSPS 64-QFN
• Manufacturer: Linear Technology

Specifications of LTC2209IUP#PBF

• Number Of Bits: 16
• Sampling Rate (per Second): 160M
• Data Interface: Parallel
• Number Of Converters: 1
• Power Dissipation (max): 1.95W
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 64-WFQFN, Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS INFORMATION
LTC2209
Figure 4a shows transformer coupling using a transmis-
sion line balun transformer. This type of transformer has
much better high frequency response and balance than
fl ux coupled center tap transformers. Coupling capaci-
tors are added at the ground and input primary terminals
to allow the secondary terminals to be biased at 1.25V.
Figure 4b shows the same circuit with components suit-
able for higher input frequencies.
Direct Coupled Circuits
Figure 5 demonstrates the use of a differential amplifi er to
convert a single ended input signal into a differential input
signal. The advantage of this method is that it provides
low frequency input response; however, the limited gain
bandwidth of any op amp or closed-loop amplifi er will de-
grade the ADC SFDR at high input frequencies. Additionally,
wideband op amps or differential amplifi ers tend to have
high noise. As a result, the SNR will be degraded unless
the noise bandwidth is limited prior to the ADC input.
20
ANALOG
ANALOG
INPUT
Figure 4b. Using a Transmission Line Balun Transformer.
Recommended for Input Frequencies from 250MHz to 500MHz
INPUT
Figure 4a. Using a Transmission Line Balun Transformer.
Recommended for Input Frequencies from 100MHz to 250MHz
0.1μF
0.1μF
0.1μF
0.1μF
T1 = MA/COM ETC1-1-13
RESISTORS, CAPACITORS
ARE 0402 PACKAGE SIZE
EXCEPT 2.2μF
T1 = MA/COM ETC1-1-13
RESISTORS, CAPACITORS
ARE 0402 PACKAGE SIZE
EXCEPT 2.2μF
1:1
1:1
T1
T1
25Ω
25Ω
25Ω
25Ω
0.1μF
0.1μF
10Ω
10Ω
4.7pF
2.2μF
2.2pF
2.2pF
5Ω
5Ω
2.2μF
4.7pF
4.7pF
5Ω
5Ω
V
A
A
V
A
A
CM
CM
IN
IN
IN
IN
+
–
+
–
LTC2209
LTC2209
2209 F04a
2209 F04b
Reference Operation
Figure 6 shows the LTC2209 reference circuitry consisting
of a 2.5V bandgap reference, a programmable gain ampli-
fi er and control circuit. The LTC2209 has three modes of
reference operation: Internal Reference, 1.25V external
reference or 2.5V external reference. To use the internal
reference, tie the SENSE pin to V
reference, simply apply either a 1.25V or 2.5V reference
voltage to the SENSE input pin. Both 1.25V and 2.5V applied
to SENSE will result in a full scale range of 2.25V
= 0). A 1.25V output, V
bias for input drive circuitry. An external bypass capacitor is
required for the V
low impedance path to ground for internal and external
circuitry. This is also the compensation capacitor for the
reference; it will not be stable without this capacitor. The
minimum value required for stability is 2.2μF .
TIE TO V
EXTERNAL 1.25V
EXTERNAL 2.5V
INTERNAL 2.5V
OR INPUT FOR
OR INPUT FOR
ANALOG
REFERENCE
REFERENCE
REFERENCE
INPUT
Figure 5. DC Coupled Input with Differential Amplifi er
DD
TO USE
AMPLIFIER = LTC6600-20,
LTC1993, ETC.
SENSE
2.2μF
DIFFERENTIAL
+
CM
–
V
HIGH SPEED
AMPLIFIER
CM
CM
Figure 6. Reference Circuit
output. This provides a high frequency
+
–
CM
BUFFER
is provided for a common mode
25Ω
25Ω
AND GAIN
CONTROL
SELECT
RANGE
DD
2.2μF
12pF
12pF
1.25V
. To use an external
V
A
A
CM
IN
IN
+
–
PGA
LTC2209
REFERENCE
BANDGAP
REFERENCE
P-P
INTERNAL
2.5V
2209 F05
ADC
(PGA
2209 F06
2209fa