|
|
PDF MAX2451CSE Data sheet ( Hoja de datos )
| Número de pieza | MAX2451CSE | |
| Descripción | 3V / Ultra-Low-Power Quadrature Demodulator | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de MAX2451CSE (archivo pdf) en la parte inferior de esta página. Total 6 Páginas | ||
|
No Preview Available !
19-0493; Rev 0; 12/95
EVAALVUAAILTAIOBNLEKIT
3V, Ultra-Low-Power
Quadrature Demodulator
_______________General Description
The monolithic MAX2451 is a quadrature demodulator
with a supporting oscillator and divide-by-8 prescaler. It
operates from a single +3V supply and draws only
5.5mA. The demodulator accepts an amplified and fil-
tered IF signal in the 35MHz to 80MHz range, and
demodulates it into I and Q baseband signals with
51dB of voltage conversion gain. The IF input is termi-
nated with a 400Ω thin-film resistor for matching to an
external IF filter. The baseband outputs are fully differ-
ential and have 1.2Vp-p signal swings.
Pulling the CMOS-compatible ENABLE pin low shuts
down the MAX2451 and reduces the supply current to
less than 2µA, typical. To minimize spurious feedback,
the MAX2451’s internal oscillator is set at twice the IF
frequency via external tuning components. The
MAX2451 comes in a 16-pin narrow SO package.
____________________________Features
o Integrated Quadrature Phase Shifters
o On-Chip Oscillator (Requires External Tuning
Circuit)
o 51dB Voltage Conversion Gain
o On-Chip Divide-by-8 Prescaler
o Baseband Output Bandwidth Up to 9MHz
o CMOS-Compatible Enable
o 5.5mA Operating Supply Current
2µA Shutdown Supply Current
________________________Applications
Digital Cordless Phones
GSM and North American Cellular Phones
Wireless LANs
Digital Communications
Pagers
______________Ordering Information
PART
MAX2451CSE
TEMP. RANGE
0°C to +70°C
PIN-PACKAGE
16 Narrow SO
________________Functional Diagram
__________________Pin Configuration
TOP VIEW
IF 1
GND 2
GND 3
N.C. 4
ENABLE 5
PRE_OUT 6
LO_VCC 7
TANK 8
MAX2451
SO
16 GND
15 VCC
14 I
13 I
12 Q
11 Q
10 LO_GND
9 TANK
DEMODULATOR
IF 1
400Ω
14
I
13
I
BIAS
12
Q
11
Q
LO_VCC 7
TANK 8
TANK 9
LO_GND 10
VCC 15
÷ 2 0°
QUADRATURE
PHASE
GENERATOR
LOCAL
OSCILLATOR
÷ 2 90°
÷4
PRESCALER
6
PRE_OUT
MAX2451
MASTER BIAS
BANDGAP
BIAS
2, 3, 16
GND
5
ENABLE
________________________________________________________________ Maxim Integrated Products 1
Call toll free 1-800-998-8800, or visit our WWW site at http://www.maxim-ic.com
for free samples or the latest literature.
1 page  
3V, Ultra-Low-Power
Quadrature Demodulator
LO_VCC
RL RL
5k 5k
Q3 TANK TANK Q4
Q1 Q2
TO QUADRATURE
GENERATOR AND
PRESCALER
TANK
C1 = 33pF
47k
L = 100nH
TANK
C2 = 33pF
1/2 KV1410
10k
1/2 KV1410
47k
0.1µF
VCTRL
Figure 2. Local-Oscillator Equivalent Circuit
Quadrature Phase Generator
The quadrature phase generator uses two latches to
divide the local-oscillator frequency by two, and gener-
ates two precise quadrature signals. Internal limiting
amplifiers shape the signals to approximate square
waves to drive the Gilbert-cell mixers. The inphase sig-
nal (at half the local oscillator frequency) is further
divided by four for the prescaler output.
Prescaler
The prescaler output, PRE_OUT, is buffered and swings
typically 0.35Vp-p with a 10kΩ and 6pF load. It can be
AC coupled to the input of a frequency synthesizer.
Master Bias
During normal operation, ENABLE should be above
VCC - 0.4V. Pulling the ENABLE input low shuts off the
master bias and reduces the circuit current to typically
2µA. The master bias section includes a bandgap ref-
erence generator and a PTAT (Proportional To Absolute
Temperature) current generator.
__________Applications Information
Figure 3 shows the implementation of a resonant tank
circuit. The inductor, two capacitors, and a dual varac-
tor form the oscillator’s resonant circuit. In Figure 3, the
oscillator frequency ranges from 130MHz to 160MHz.
To ensure reliable start-up, the inductor is directly con-
nected across the local oscillator’s tank ports. The two
33pF capacitors affect the Q of the resonant circuit.
Other values may be chosen to meet individual appli-
Figure 3. Typical Resonant Tank Circuit
cation requirements. The oscillation frequency can be
determined using the following formula:
fo = 1
2π LEQCEQ
where
CEQ =
1+
1
1+
2
+ CSTRAY
C1 C2 CVAR
and
LEQ = L + LSTRAY
where CSTRAY = parasitic capacitance and LSTRAY =
parasitic inductance.
To alter the oscillation frequency range, change the
inductance, the capacitance, or both. For best phase-
noise performance, keep the Q of the resonant tank as
high as possible:
Q = REQ CEQ
LEQ
where REQ ≈ 10kΩ (Figure 2).
The oscillation frequency can be changed by altering
the control voltage, VCTRL.
_______________________________________________________________________________________ 5
5 Page | ||
| Páginas | Total 6 Páginas | |
| PDF Descargar | [ Datasheet MAX2451CSE.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| MAX2451CSE | 3V / Ultra-Low-Power Quadrature Demodulator | Maxim Integrated |
| 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 |