DC1398A-GA Linear Technology, DC1398A-GA Datasheet - Page 15

• Manufacturer Part Number: DC1398A-GA
• Description: BOARD EVAL LTM9001-GA
• Manufacturer: Linear Technology
• Type: Baseband Receiverr

Specifications of DC1398A-GA

• Design Resources: Demo Circuit 1398A Schematic
• Frequency: 0Hz ~ 300MHz
• Kit Contents: Board, Manual
• Features: LTM9001 16bit Receiver Subsystem, DC-10MHz LPF
• Tool / Board Applications: Wireless Connectivity-ZigBee, RF, Infrared, USB
• Development Tool Type: Hardware - Eval/Demo Board
• Mcu Supported Families: LTM9001
• For Use With/related Products: LTM9001
• Lead Free Status / RoHS Status: Not applicable / Not applicable

APPLICATIONS INFORMATION
Alternatively, one could apply a narrowband impedance
match at the inputs for frequency selection and/or noise
reduction.
Referring to Figure 4, amplifi er inputs can be easily
confi gured for single-ended input without a balun. The
signal is fed to one of the inputs through a matching
network while the other input is connected to the same
impedance. In general, the single-ended input impedance
and termination resistor R
combination of R
Table 3. Single-Ended Amplifi er Input Termination Values
The LTM9001 amplifi er is stable with all source impedances.
The overall differential gain is affected by the source
impedance in Figure 5:
The noise performance of the amplifi er also depends upon
the source impedance and termination. For example, an
input 1:4 transformer in Figure 3 improves the input noise
fi gure by adding 6dB voltage gain at the inputs.
Reference and SENSE Pin Operation
Figure 6 shows the converter reference circuitry consisting
of a 2.5V bandgap reference, a programmable gain amplifi er
and control circuit. There are 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
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 the maximum full-scale range.
A
V
= | V
400Ω
200Ω
50Ω
Z
IN
OUT
/V
IN
S
, Z
| = (1000/(R
IN
/2 and R
DD
. To use an external reference,
T
S
F
are determined by the
.
+ Z
R
T
IN
68.5Ω
150Ω
Figure 4
59Ω
/2))
TIE TO V
EXTERNAL 1.25V
EXTERNAL 2.5V
INTERNAL 2.5V
OR INPUT FOR
OR INPUT FOR
REFERENCE
+
–
REFERENCE
REFERENCE
DD
+
–
0.1μF
R
V
50Ω
TO USE
R
IN
S
Figure 4. Input Termination for Differential
50Ω Input Impedance Using Shunt Resistor
V
/R
R
R
S
R
IN
s
s
T
T
/2
/2
Figure 5. Calculate Differential Gain
0.1μF
0.1μF
R
SENSE
IN
IN
T
Figure 6. Reference Circuit
+
–
IN
IN
+
–
Z
Z
IN
IN
Z
Z
/2
/2
IN
IN
/2
/2
LTM9001-GA
AND GAIN
CONTROL
SELECT
RANGE
R
R
R
R
F
F
LTM9001-GA
F
F
LTM9001-GA
9001-GA F05
9001-GA F04
PGA
REFERENCE
BANDGAP
REFERENCE
INTERNAL
2.5V
15
ADC
9001-GA F06
9001gaf