LTC5588IPF-1#PBF Linear Technology, LTC5588IPF-1#PBF Datasheet - Page 18

• Manufacturer Part Number: LTC5588IPF-1#PBF
• Description: IC, MODULATOR, 200MHz To 6GHz, TQFN-24
• Manufacturer: Linear Technology

Specifications of LTC5588IPF-1#PBF

• Frequency Range: 200MHz To 6GHz
• Rf Type: GSM, LTE, WCDMA, WiMax
• Supply Voltage Range: 3.15V To 3.45V
• Rf Ic Case Style: TQFN
• No. Of Pins: 24
• Operating Temperature Range: -40°C To +85°C
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

LTC5588-1
APPLICATIONS INFORMATION
It is recommended to compensate the baseband input
impedance in the baseband lowpass filter design in order
to achieve best gain flatness vs baseband frequency. The
S-parameters for (each of) the baseband inputs is given
in Table 1.
Table 1. Single-Ended BB Input Impedance vs Frequency for
EN = High and V
18
FREQUENCY
(MHz)
1000
100
140
200
250
300
350
400
450
500
600
700
800
900
0.1
16
30
60
1
2
4
8
DC
–3200-j1500
–2100-j1900
= 0.5V
IMPEDANCE
–3900-j340
–3700-j950
–860-j1600
–300-j990
BB INPUT
–1.4-j120
–87-j520
–35-j308
–16-j226
1.4-j102
10.5-j27
10.5-j23
Figure 2: Baseband Interface with 5th-Order Filter and 0.5V
–6-j154
4.4-j87
5.4-j74
8.3-j58
9.4-j47
–3700
10-j38
10-j32
7-j66
10mA ±10mA
10mA ±10mA
DAC
REFLECTION COEFFICIENT
MAG
1.03
1.03
1.03
1.03
1.03
1.03
1.03
1.03
1.04
1.03
1.02
1.01
0.99
0.96
0.94
0.90
0.87
0.82
0.77
0.74
0.71
0.69
R1A
71.5
R1B
71.5
250nH
250nH
C1A
47pF
C1B
47pF
L1A
L1B
ANGLE
–0.13
–0.13
–0.37
–0.68
–1.38
–2.79
–10.6
–18.2
–24.8
–102
–113
–122
–129
–5.3
–36
–45
–52
–59
–67
–73
–80
–92
GND
250nH
250nH
C2
39pF
L2A
L2B
The circuit is optimized for a common mode voltage of
0.5V which should be externally applied. The baseband
pins should not be left floating to cause the internal PNP’s
base current to pull the common mode voltage higher
than the 0.55V limit, generating excessive current flow. If
it occurs for an extended period, damage to the IC may
result. In shutdown mode it is recommended to terminate
to ground or to a 0.5V source with a value lower than
200Ω. The PNP’s base current is about –136μA ranging
from –250μA to –50μA.
It is recommended to drive the baseband inputs differen-
tially to reduce even-order distortion products. When a DAC
is used as the signal source, a reconstruction filter should
be placed between the DAC output and the LTC5588-1
baseband inputs to avoid aliasing.
Figure 2 shows a typical baseband interface for zero-IF
repeater application. A 5th-order lowpass ladder filter is
used with –0.3dB cut-off of 60MHz. C1A, C1B, C3A and
C3B are configured in a single-ended fashion in order to
suppress common mode noise. L3A and L3B (0402 size)
are used to compensate for passband droop due to the
finite quality factor of the inductors L1A, L1B, L2A and
L2B (0603 size). R3A and R3B improves the out-of-band
noise performance. R3A = R3B = 0Ω (L3A and L3B omit-
ted) provides best out-of-band noise performance but no
passband droop compensation. In that case, L1A, L1B,
L2A and L2B may have to be increased in size (higher
quality factor) to limit passband droop.
C3A
47pF
C3B
47pF
0.5V
0.5V
DC
DC
R2A
165
R2B
165
CM
DAC (Only I Channel is Shown)
R2C
249
100nH
100nH
L3A
L3B
71.5
71.5
R3A
R3B
55881 F02
BBPI
BBMI
55881fb