LTC5540IUH#PBF Linear Technology, LTC5540IUH#PBF Datasheet - Page 12

• Manufacturer Part Number: LTC5540IUH#PBF
• Description: IC, DOWN CONVERTING MIXER 1.3GHZ, QFN-20
• Manufacturer: Linear Technology

Specifications of LTC5540IUH#PBF

• Frequency Range: 600MHz To 1.3GHz
• Supply Voltage Range: 3.1V To 3.5V
• Rf Ic Case Style: QFN
• No. Of Pins: 20
• Operating Temperature Range: -40°C To +85°C
• Rf Type: GSM, LTE, WCDMA, WiMax
• Operating Supply Voltage: 3.3V
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

LTC5540
applicaTions inForMaTion
The nominal LO input level is 0dBm although the limiting
amplifiers will deliver excellent performance over a ±6dBm
input power range. LO input power greater than 6dBm
may cause conduction of the internal ESD diodes. Series
capacitors C3 and C4 optimize the input match and provide
DC blocking.
The LO1 input impedance and input reflection coefficient,
versus frequency, is shown in Table 3. The LO2 port
is identical due to the symmetric device layout and
packaging.
Table 3. LO1 Input Impedance vs Frequency
(at Pin 11, No External Matching, LOSEL = Low)
IF Output
The IF amplifier, shown in Figure 7, has differential open-
collector outputs (IF
(IFGND), and a pin for modifying the internal bias (IFBIAS).
The IF outputs must be biased at the supply voltage (V
which is applied through matching inductors L1 and L2.
Alternatively, the IF outputs can be biased through the
center tap of a transformer. Each IF output pin draws
approximately 48mA of DC supply current (96mA total).
Resistor R2 is used to improve the impedance match.
IFGND (pin 16) must be grounded or the amplifier will
not draw DC current. Grounding through inductor L3
improves LO-IF and RF-IF leakage performance but is
otherwise not necessary. High DC resistance in L3 will
reduce the IF amplifier supply current, which will degrade
RF performance.
For optimum single-ended performance, the differential
IF outputs must be combined through an external IF

FREQUENCY
(GHz)
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
+
and IF
IMPEDANCE
48.9 + j30.6
62.8 + j29.4
78.0 + j17.2
80.4 – j4.55
68.3 – j20.5
54.6 – j24.1
44.7 – j22.3
38.1 – j18.7
33.8 – j14.9
INPUT
–
), a DC ground return pin
MAG
0.28
0.25
0.24
0.23
0.23
0.24
0.25
0.26
0.3
S11
ANGLE
–110.5
–127.3
–38.4
–66.3
–90.1
74.9
51.9
23.9
–6.5
CCIF
),
transformer or discrete IF balun circuit. The evaluation
board (see Figures 1 and 2) uses a 4:1 ratio IF transformer
for impedance transformation and differential to single-
ended transformation. It is also possible to eliminate the
IF transformer and drive differential filters or amplifiers
directly.
The IF output impedance can be modeled as 320Ω in
parallel with 2.3pF at IF frequencies. An equivalent small-
signal model (including bondwire inductance) is shown in
Figure 8. Frequency-dependent differential IF output
impedance is listed in Table 4. This data is referenced
to the package pins (with no external components) and
includes the effects of IC and package parasitics.
Figure 7. IF Amplifier Schematic with Bandpass Match
DC POWER)
(OPTION TO
REDUCE
IFBIAS
R1
V
CC
Figure 8. IF Output Small-Signal Model
20
BIAS
4mA
19
19
IF
0.9nH
V
IF
CCIF
+
+
L1
AMP
R2
T1
IF
R IF
C IF
C8
C10
L2
4:1
IF
–
18
LTC5540
18
96mA
IF
16
IF
0.9nH
OUT
–
IFGND
LTC5540
L3 (OR SHORT)
5540 F07
5540 F08
5540f