|
|
PDF LT5558 Data sheet ( Hoja de datos )
| Número de pieza | LT5558 | |
| Descripción | 600MHz to 1100MHz High Linearity Direct Quadrature Modulator | |
| Fabricantes | Linear | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LT5558 (archivo pdf) en la parte inferior de esta página. Total 16 Páginas | ||
|
No Preview Available !
FEATURES
■ Direct Conversion from Baseband to RF
■ High OIP3: + 22.4dBm at 900MHz
■ Low Output Noise Floor at 20MHz Offset:
No RF: –158dBm/Hz
POUT = 4dBm: –152.7dBm/Hz
■ Low Carrier Leakage: –43.7dBm at 900MHz
■ High Image Rejection: –49dBc at 900MHz
■ 3 Channel CDMA2000 ACPR: –70.4dBc at 900MHz
■ Integrated LO Buffer and LO Quadrature Phase
Generator
■ 50Ω AC-Coupled Single-ended LO and RF Ports
■ High Impedance Interface to Baseband Inputs
with 2.1V Common Mode Voltage
■ 16-Lead QFN 4mm × 4mm Package
APPLICATIONS
■ RFID Single-Sideband Transmitters
■ Infrastructure TX for Cellular and ISM Bands
■ Image Reject Up-Converters for Cellular Bands
■ Low-Noise Variable Phase-Shifter for 600MHz to
1100MHz Local Oscillator Signals
■ Microwave Links
LT5558
600MHz to 1100MHz
High Linearity Direct
Quadrature Modulator
DESCRIPTION
The LT®5558 is a direct I/Q modulator designed for high
performance wireless applications, including wireless
infrastructure. It allows direct modulation of an RF signal
using differential baseband I and Q signals. It supports
GSM, EDGE, CDMA, CDMA2000, and other systems. It
may also be configured as an image reject upconverting
mixer, by applying 90° phase-shifted signals to the I and
Q inputs. The high impedance I/Q baseband inputs consist
of voltage-to-current converters that in turn drive double-
balanced mixers. The outputs of these mixers are summed
and applied to an on-chip RF transformer, which converts
the differential mixer signals to a 50Ω single-ended output.
The balanced I and Q baseband input ports are intended
for DC coupling from a source with a common-mode
voltage level of about 2.1V. The LO path consists of an LO
buffer with single-ended input, and precision quadrature
generators which produce the LO drive for the mixers.
The supply voltage range is 4.5V to 5.25V.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
600MHz to 1100MHz Direct Conversion Transmitter Application
∫ IDAC
EN
∫ QDAC
VCC
8, 13
5V
2 x 100nF
14
16 V-1
I-CH
1
O°
LT5558
RF = 600MHz TO
1100MHz
11 PA
7 Q-CH
5 V-1
90°
BALUN
BASEBAND
GENERATOR
2, 4, 6, 9, 10,
12, 15, 17
3
VCO/SYNTHESIZER
5558 TA01
CDMA2000 ACPR, AltCPR and Noise vs
RF Output Power at 900MHz for 1 and 3 Carriers
–40
DOWNLINK TEST
MODEL 64 DPCH
–50
3-CH ACPR
3-CH ALTCPR
–60
–70
–110
–120
–130
1-CH ACPR
–140
–80 1-CH ALTCPR
1-CH NOISE
–150
3-CH NOISE
–90
–30 –25 –20 –15 –10 –5
–160
0
RF OUTPUT POWER PER CARRIER (dBm)
5558 TA01b
5558fa
1
1 page  
LT5558
TYPICAL PERFORMANCE CHARACTERISTICS VCC = 5V, EN = High, TA = 25°C, fLO = 900MHz,
fRF = 902MHz, PLO = 0dBm. BBPI, BBMI, BBPQ, BBMQ CM input voltage = 2.1VDC, baseband input frequency = 2MHz, I and Q 90°
shifted, without image or LO feedthrough nulling. fRF = fBB + fLO (upper side-band selection). PRF(OUT) = –10dBm (–10dBm/tone for
2-tone measurements), unless otherwise noted. (Note 3)
Noise Floor vs RF Frequency
–157
fLO = 900MHz (FIXED)
NO BASEBAND SIGNAL
–158
–159
–160
5V, –40°C
5V, 25°C
–161
5V, 85°C
4.5V, 25°C
5.5V, 25°C
–162
550 650 750 850 950 1050 1150 1250
RF FREQUENCY (MHz)
5558 G24
Image Rejection vs LO Frequency
–30
5V, –40°C
5V, 25°C
–35 5V, 85°C
4.5V, 25°C
5.5V, 25°C
–40
–45
–50
–55
550 650 750 850 950 1050 1150 1250
LO FREQUENCY (MHz)
5558 G10
LO and RF Port Return Loss
vs RF Frequency
0
LO PORT, EN = LOW
–10 LO PORT, EN = HIGH, PLO = 0dBm
–20 RF PORT, EN = LOW
RF PORT, EN = HIGH,
PLO = 0dBm
–30
LO PORT, EN = HIGH,
PLO = –10dBm
RF PORT, EN = HIGH, NO LO
–40
550 650 750 850 950 1050 1150 1250
FREQUENCY (MHz)
5558 G25
Absolute I/Q Gain Imbalance vs
LO Frequency
0.2
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
0.1
0
550 650 750 850 950 1050 1150 1250
LO FREQUENCY (MHz)
5558 G11
Absolute I/Q Phase Imbalance vs
LO Frequency
4
5V, –40°C
5V, 25°C
5V, 85°C
3 4.5V, 25°C
5.5V, 25°C
2
1
0
550 650 750 850 950 1050 1150 1250
LO FREQUENCY (MHz)
5558 G12
Voltage Gain vs LO Power
–2
–4
–6
–8
–10
–12
–14
–16
–18
–20
–20 –16 –12 –8
–4
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
048
LO INPUT POWER (dBm)
5558 G13
Output IP3 vs LO Power
24
22
20
18 5V, –40°C
5V, 25°C
16 5V, 85°C
4.5V, 25°C
14 5.5V, 25°C
12 fBB, 1 = 2MHz
fBB, 2 = 2.1MHz
10
–20 –16 –12 –8 –4 0
4
LO INPUT POWER (dBm)
8
5558 G14
LO Feedthrough vs LO Power
–40
–42
–44
–46
–48
–50
–20 –16 –12 –8 –4
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
048
LO INPUT POWER (dBm)
5558 G15
Image Rejection vs LO Power
–35
–40
–45
–50
–55
–20
5V, –40°C
5V, 25°C
5V, 85°C
4.5V, 25°C
5.5V, 25°C
–16 –12 –8 –4 0 4
LO INPUT POWER (dBm)
8
5558 G16
5558fa
5
5 Page 
LT5558
APPLICATIONS INFORMATION
The RF output S22 with no LO power applied is given in
Table 4.
Table 4. RF Port Output Impedance vs Frequency for EN = High
and No LO Power Applied
FREQUENCY
(MHz)(
OUTPUT IMPEDANCE (Ω)
S22
MAG ANGLE
500
23.4 + j5.0
0.367 165.5
600
31.7 + j10.7
0.257 142.0
700
44.1 + j9.5
0.118 116.1
800
50.9 – j1.7
0.019 –60.8
900
46.8 – j11.1
0.118 –99.3
1000
40.8 – j13.5
0.178 –115.5
1100
36.6 – j12.6
0.209 –128.1
1200
34.3 – j10.5
0.222 –139.0
For EN = Low the S22 is given in Table 5.
To improve S22 for lower frequencies, a series capacitor
can be added to the RF output. At higher frequencies, a
shunt inductor can improve the S22. Figure 5 shows the
equivalent circuit schematic of the RF output.
Table 5. RF Port Output Impedance vs Frequency for EN = Low
FREQUENCY
(MHz)
OUTPUT IMPEDANCE (Ω)
S22
MAG ANGLE
500
21.8 + j4.8
0.398 166.5
600
28.4 + j11.8
0.311 142.9
700
40.2 + j15.4
0.200 112.9
800
54.3 + j8.3
0.090
58.1
900
56.7 – j7.2
0.092 –43.3
1000
49.2 – j15.8
0.158 –83.8
1100
41.9 – j17.0
0.203 –105.0
1200
37.3 – j15.3
0.225 –120.0
52Ω
VCC
21pF
1pF 7nH
RF
OUTPUT
5558 F05
Figure 5. Equivalent Circuit Schematic of the RF Output
Note that an ESD diode is connected internally from the
RF output to the ground. For strong output RF signal
levels (higher than 3dBm), this ESD diode can degrade
the linearity performance if an external 50Ω termination
impedance is connected directly to ground. To prevent this,
a coupling capacitor can be inserted in the RF output line.
This is strongly recommended during 1dB compression
measurements.
Enable Interface
Figure 6 shows a simplified schematic of the EN pin inter-
face. The voltage necessary to turn on the LT5558 is 1V.
To disable (shut down) the chip, the enable voltage must
be below 0.5V. If the EN pin is not connected, the chip is
disabled. This EN = Low condition is guaranteed by the
75kΩ on-chip pull-down resistor.
It is important that the voltage at the EN pin does not
exceed VCC by more than 0.5V. If this should occur, the
full-chip supply current could be sourced through the EN
pin ESD protection diodes, which are not designed for this
purpose. Damage to the chip may result.
VCC
EN
75k 25k
5558 F06
Figure 6. EN Pin Interface
Evaluation Board
Figure 7 shows the evaluation board schematic. A good
ground connection is required for the LT5558’s Exposed
Pad. If this is not done properly, the RF performance will
degrade. Additionally, the Exposed Pad provides heat sink-
ing for the part and minimizes the possibility of the chip
overheating. R1 (optional) limits the EN pin current in the
event that the EN pin is pulled high while the VCC inputs
are low. The application board PCB layouts are shown in
Figures 8 and 9.
5558fa
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet LT5558.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LT5554 | Broadband Ultra Low Distortion 7-Bit Digitally Controlled VGA | Linear |
| LT5557 | 400MHz to 3.8GHz 3.3V Active Downconverting Mixer |  Linear Technology |
| LT5558 | 600MHz to 1100MHz High Linearity Direct Quadrature Modulator | Linear |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |