MAX2108 ,Direct-Conversion Tuner ICELECTRICAL CHARACTERISTICS(V = +5V; PS_SEL = 0.5V; P = -20dBm; f = f +125kHz; GC set via servo loop ..
MAX2108 ,Direct-Conversion Tuner ICApplications Ordering InformationDirecTV, PrimeStar, EchoStar DBS TunersPART TEMP RANGE PIN-PACKAGE ..
MAX2108CEG ,Direct-Conversion Tuner ICELECTRICAL CHARACTERISTICS(V = +5V; PS_SEL = 0.5V; P = -20dBm; f = f +125kHz; GC set via servo loop ..
MAX2108CEG ,Direct-Conversion Tuner ICFeaturesThe MAX2108 is a low-cost direct-conversion tuner IC' Low-Cost Architecturedesigned for use ..
MAX2108CEG ,Direct-Conversion Tuner ICApplicationsDirecTV, PrimeStar, EchoStar DBS TunersDVB-Compliant DBS TunersOrdering InformationCell ..
MAX211 ,+5V RS-232 Transceivers with 0.1µF External Capacitors. Maxim has incorporated many new features into the RS-232 components that provide engineering value.MAX200–MAX209/ +5V, RS-232 TransceiversMAX211/MAX213 with 0.1μF External Capacitors
MAX5171BEEE+ ,Low-Power, Serial, 14-Bit DACs with Force-Sense Voltage-OutputELECTRICAL CHARACTERISTICS—MAX5171(V = +5.0V ±10%, V = +2.5V, AGND = DGND, FB = OUT, R = 5kΩ, C = 1 ..
MAX5172AEEE ,Low-Power / Serial / 14-Bit DACs with Voltage OutputApplicationsMAX5172AEEE -40°C to +85°C 16 QSOP ±2MAX5172BEEE -40°C to +85°C 16 QSOP ±4Industrial Pr ..
MAX5173AEEE ,Low-Power / Serial / 14-Bit DACs with Force/Sense Voltage Outputfeatures include software and hardware shut-' User-Programmable Digital Output Pin Allowsdown, shut ..
MAX5174AEEE ,Low-Power, Serial, 12-Bit DACs with Voltage OutputApplicationsPin ConfigurationIndustrial Process ControlsTOP VIEWDigital Offset and Gain AdjustmentO ..
MAX5174BEEE ,Low-Power, Serial, 12-Bit DACs with Voltage Outputfeatures include software and ' SPI/QSPI/MICROWIRE-Compatible 3-Wire Serialhardware shutdown, shutd ..
MAX517ACPA ,2-Wire Serial 8-Bit DACs with Rail-to-Rail OutputsMAX517/MAX518/MAX51919-0393; Rev 0; 5/952-Wire Serial 8-Bit DACs withRail-to-Rail Outputs__________ ..
MAX2108
Direct-Conversion Tuner IC
General DescriptionThe MAX2108 is a low-cost direct-conversion tuner IC
designed for use in digital direct-broadcast satellite
(DBS) television set-top box units and microwave links.
Its direct-conversion architecture reduces system cost
compared to devices with IF-based architectures.
The MAX2108 directly tunes L-band signals to base-
band using a broadband I/Q downconverter. The oper-
ating frequency range spans from 950MHz to
2150MHz. The IC includes a low-noise amplifier (LNA)
with gain control, two downconverter mixers with output
buffers, a 90°quadrature generator, and a divide-by
32/33 prescaler.
ApplicationsDirecTV, PrimeStar, EchoStar DBS Tuners
DVB-Compliant DBS Tuners
Cellular Base Stations
Wireless Local Loop
Broadband Systems
LMDS
Microwave Links
FeaturesLow-Cost ArchitectureOperates from Single +5V SupplyOn-Chip Quadrature Generator, Dual-Modulus
Prescaler (/32, /33)Input Levels: -20dBm to -70dBm per CarrierOver 50dB RFGain-Control Range10dB Noise Figure at Maximum Gain+8dBm IIP3 at Minimum Gain
MAX2108
Direct-Conversion Tuner ICPS_SELGCGNDGNDRFINRFINGNDIOUTIOUT
PSOUT
VCCVCC
VCC
VCC
PSOUTGNDGNDN.C.LOLOQOUTQOUTN.C.GND11109876543211415161718192021222324
MAX2108
/32
/3390
Functional Diagram19-1449; Rev 1; 6/05
Ordering Information
Pin Configuration appears at end of data sheet.
PARTTEMP RANGEPIN-PACKAGEMAX2108CEG0°C to +70°C24 QSOP
MAX2108CEG+0°C to +70°C24 QSOP
+Denotes lead-free package.
MAX2108
Direct-Conversion Tuner IC
ABSOLUTE MAXIMUM RATINGS
DC ELECTRICAL CHARACTERISTICS(VCC= +4.75V to +5.25V; VGC= 1.3V; PS_SEL = 0.5V; IOUT, IOUT, QOUT, QOUT= terminated with 2.5kΩto GND; no input signal
applied; TA= 0°C to +70°C; unless otherwise noted. Typical values are at VCC= +5V, TA= +25°C.)
AC ELECTRICAL CHARACTERISTICS(VCC= +5V; PS_SEL = 0.5V; PRFIN= -20dBm; fLO= fRFIN +125kHz; GC set via servo loop for VIOUT- VIOUT= 200mVp-p (differen-
tial); TA= +25°C; unless otherwise noted.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
VCCto GND..............................................................-0.3V to +7V
VCCto Any Other VCC...........................................-0.3V to +0.3V
All Other Pins to GND.................................-0.3V to (VCC+ 0.3V)
RFIN to RFIN..........................................................................±2V
LO to LO................................................................................±2V
Short-Circuit Current
IOUT, IOUT, QOUT, QOUTto GND.................................10mA
PSOUT, PSOUTto GND...................................................40mA
Short-Circuit Duration IOUT to IOUT, QOUT to QOUT,
PSOUT to PSOUT............................................................10sec
Continuous Power Dissipation (TA= +70°C)
24 QSOP (derate 10mW/°C above TA= +70°C)..........800mW
Operating Temperature Range...............................0°C to +70°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
0 < VPS_SEL< VCC
1V < VGC< 4V
CONDITIONS0.5VTHLPS_SEL Logic-Low Threshold2.4VTHH105152ICCSupply Current
PS_SEL Logic-High Threshold-30+10IPS_SELPS_SEL Input Bias Current-80+80IGCGC Input Bias Current
UNITSMINTYPMAXSYMBOLPARAMETER2.93.353.8VCMIOUT, IOUT, QOUT, QOUT
Common-Mode Output Voltage
950MHz < fRFIN< 2150MHz, PLO= -5dBm,
VIOUT- VIOUT= 10mVP-P, TA= 0°C +70°C
950MHz < fRFIN< 2150MHz, PLO= -5dBm
1V < VGC< 4V, PLO= -5dBm
CONDITIONSdBm-70PRFINMINRFIN Minimum Input Power
(Note 2)
dBm-20PRFINMAX
MHz9502150fRFINRFIN Frequency Range (Note 1)
RFIN Maximum Input Power
(Note 2)
dBm-5External LO Drive Level (Note 2)50Gain-Control Range (Note 2)
UNITSMINTYPMAXSYMBOLPARAMETERVGC= 4V, fLO= 1750MHzdB10NFNoise Figure
dBm14IIP2
dBm8IIP3RFIN Input Third-Order
Intercept Point (Note 3)
RFIN Input Second-Order
Intercept Point (Note 4)
MAX2108
Direct-Conversion Tuner IC
AC ELECTRICAL CHARACTERISTICS (continued)(VCC= +5V; PS_SEL = 0.5V; PRFIN= -20dBm; fLO= fRFIN +125kHz; GC set via servo loop for VIOUT- VIOUT= 200mVp-p (differen-
tial); TA= +25°C; unless otherwise noted.)
Note 1:AC specifications with minimum/maximum limits are met within this frequency range.
Note 2:LO and LOare differentially driven through an AC-coupled matching network.
Note 3:PRFIN= -20dBm per tone, GC set via servo loop for VIOUT- VIOUT= 20mVp-p per tone. f1RFIN= 1749MHz, f2RFIN=
1751MHz, fLO= 1740MHz.
Note 4:PRFIN= -20dBm per tone, GC set via servo loop for VIOUT- VIOUT= 20mVp-p per tone. f1RFIN= 1200MHz, f2RFIN=
2150MHz, fLO= 951MHz.
CONDITIONSUNITSMINTYPMAXSYMBOLPARAMETERVPS_SEL< 0.5V
CPSOUT= CPSOUT= 10pF to GND33
VPS_SEL> 2.4VPrescaler Divide Ratio
VP-P1.0VPSOUT -PSOUT
Differential Prescaler Output
Swing32
At -3dB attenuation
fIOUT= fIOUT= fQOUT= fQOUT= 20MHz
MHz150
fIOUT= fIOUT= fQOUT= fQOUT= 125kHz
Baseband Bandwidth33I/Q Channel Differential
Output Impedance
degrees3I/Q Channel Quadrature
Phase Error (Note 2)
fIOUT= fIOUT= fQOUT=fQOUT= 125kHzdB1I/Q Amplitude Mismatch
(Note 2)
fIOUT= fIOUT= fQOUT= fQOUT= 10MHz,
no output loadVP-P1.4I/Q Channel Clipping Level
Typical Operating Characteristics(TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX2108 toc01
VCC(V)
ICC
(mA)
TA = +70°C
TA = +25°C
TA = 0°C
CARRIER LEVEL vs. GAIN CONTROL
MAX2108 toc02
GC VOLTAGE (V)
RF LEVEL (dBm)
GC SET FOR 10mVP-P
BASEBAND OUTPUT
fRFIN = 1750 MHz
INPUT IP3 vs. FREQUENCY
MAX2108 toc03
RF FREQUENCY (MHz)
IIP3 (dBm)
TWO-TONE FREQUENCY
SPACING EQUALS 2MHz
MAX2108
Direct-Conversion Tuner ICIM3 vs. CARRIER LEVEL
MAX2108 toc04
RF INPUT LEVEL (dBm)
IM3 (dBc)
TWO-TONE FREQUENCY
SPACING EQUALS 2MHz
NOISE FIGURE vs. FREQUENCY
MAX2108 toc05
RF FREQUENCY (MHz)
NF (dB)
VGC = 4V262822243032343638
NOISE FIGURE vs. INSERTION GAIN
(RF TO BASEBAND)MAX2108 toc06
GAIN (dB)
NF (dB)
RF PORT SERIES IMPEDANCE
vs. FREQUENCY
MAX2108 toc07
FREQUENCY (MHz)
SERIES IMPEDANCE (
VGC = 4V
REAL
IMAGINARY
RF PORT SERIES IMPEDANCE
vs. FREQUENCY
MAX2108 toc08
FREQUENCY (MHz)
SERIES IMPEDANCE (REAL
IMAGINARY
VGC = 1V
LO PORT SERIES IMPEDANCE
vs. FREQUENCY
MAX2108 toc10
FREQUENCY (MHz)
SERIES IMPEDANCE (
REAL
IMAGINARY
SINGLE-ENDED
NORMALIZED BASEBAND GAIN
vs. BASEBAND FREQUENCY
MAX2108 toc11
BASEBAND FREQUENCY (MHz)
NORMALIZED BASEBAND GAIN (dB)
ypical Operating Characteristics (continued)(TA = +25°C, unless otherwise noted.)
MAX2108
Direct-Conversion Tuner IC
NAMEFUNCTIONIOUTInverting I-Channel Baseband Output
PIN
Pin DescriptionIOUTNoninverting I-Channel Baseband OutputVCCDownconverter +5V Supply. Bypass with a 10pF capacitor to GND as close to the IC as possible. Connect
an additional 0.1µF capacitor in parallel with the 10pF capacitor.GNDGround. Connect to a low-inductance ground plane.VCCRF +5V Supply. Bypass with a 22pF capacitor to GND as close to the IC as possible.RFINInverting RF Input. Connect to a 22pF capacitor in series with a 75Ωresistor to GND.RFINNoninverting RF Input. Connect via matching network to a 75Ωcable.
8, 9GNDRF Ground. Connect to a low-inductance ground plane.GCGain-Control Input. Apply a voltage between 1V and 4V to control the gain of the RF amplifier. Bypass with a
1000pF capacitor to minimize noise on the control line.PS_SELPrescaler Modulus Control. Drive PS_SEL <0.5V to operate in divide-by-33 mode. Drive PS_SEL >2.4V to
operate in divide-by-32 mode.VCCPrescaler +5V Supply. Bypass with a 1000pF capacitor to GND.PSOUTInverting Prescaler OutputPSOUTNoninverting Prescaler OutputGNDPrescaler Ground. Connect to a low-inductance ground plane.GNDLocal Oscillator Ground. Connect to a low-inductance ground plane.
17, 20N.C.No Connection. Do not make any connection to this pin.LOInverting LO InputLONoninverting LO InputVCCLocal Oscillator +5V Supply. Bypass with a 22pF capacitor and a 0.1µF capacitor to pin 16.GNDDownconverter Ground. Connect to a low-inductance ground plane.QOUTNoninverting Q-Channel Baseband OutputQOUTInverting Q-Channel Baseband Output
MAX2108
Direct-Conversion Tuner IC
_______________Detailed Description The MAX2108 downconverts signals in the 950MHz to
2150MHz range directly to baseband in-phase/
quadrature-phase (I/Q) signals. It is designed for digital
DBS tuner applications where a direct downconversion
provides a cost savings over multiple-conversion
approaches. However, the MAX2108 is applicable to
any system requiring a broadband I/Q downconversion.
Internally, the MAX2108 consists of a broadband front-
end variable gain stage, a quadrature downconverter,
a 90°quadrature generator, a divide-by 32/33
prescaler, and high-linearity I and Q baseband buffers.
The front-end gain-control range is over 50dB.
Specifically, when the MAX2108 operates in an auto-
matic gain control (AGC) loop, VGCis adjusted by the
loop so that a sine wave at RFIN ranging in power from
-70dBm to -20dBm produces a sine wave across IOUT,
IOUTand QOUT, QOUTat 10mVP-Pdifferential. The
noise figure is at its minimum when GC is at its maxi-
mum gain setting.
The quadrature downconverter follows the front-end
variable-gain amplifier. The mixer LO ports are fed with
the two LO signals, which are 90°apart in phase.
These quadrature LO signals are generated internally
using the signal from the LO and LOpins.
The resulting I/Q baseband signals are fed through
separate I-channel and Q-channel baseband buffers.
The outputs are capable of driving lowpass filters with
100Ωcharacteristic impedance (that is, the equivalent
of an AC-coupled 100Ωload). The baseband -3dB out-
put bandwidth is approximately 150MHz.
Applications Information
Front-End Tuner Circuitry
for DBS TunersIn a typical application, the signal path ahead of the
tuner includes a discrete low-noise amplifier/buffer and
a PIN-diode attenuator. Since the MAX2108 satisfies
the noise and linearity requirements for DBS, this front-
end circuitry is not required.
In some very high linearity applications, such as single
channel-per-carrier (SCPC), a varactor-tuned pre-
selection bandpass filter is added between a discrete
LNA and the MAX2108. The filter provides a means of
broadly filtering adjacent interference signals, thus
improving the intermodulation performance of the tuner.
Additionally, the filter removes RF interference at twice
the LO frequency, which otherwise adds to the co-
channel interference. The MAX2108 rejects this carrier
to approximately 25dBc.
PortThe MAX2108 accepts either a single-ended or differ-
ential LO signal. For single-ended drive, AC-couple the
LO signal into LO with a 47pF capacitor, and bypassto ground with a 47pF capacitor in series with a
25Ωresistor. Drive LO with a 50Ωsource at -5dBm.
PrescalerThe prescaler requires a stable logic level at PS_SEL
4ns before the falling edge of PSOUT, PSOUTto assert
the desired modulus. The logic level at PS_SEL must
remain static until 2ns after this falling edge.
Baseband BuffersThe MAX2108 baseband buffers provide at least
10mVp-p differential swing across IOUT, IOUTand
QOUT, QOUT, and are capable of driving an AC-cou-
pled 100Ωdifferential load. In a typical application,
IOUT, IOUT, QOUT, and QOUTdrive a 5th- or 7th-order
lowpass filter for ADC anti-aliasing purposes (see the
Filters in Direct-Conversion Tuners section ). In general,
additionalgain is required, after the filters. This is
accomplished with a pair of video-speed op amps,
such as the MAX4216 dual video op amp, or a simple
transistor circuit. Contact Maxim for more information
about the MAX4216.
Layout ConsiderationsObserve standard RF layout rules. A ground plane is
essential; when connecting areas of ground plane
between layers, use vias liberally. If a ground plane is
used under the lowpass filters, note that the filter
response may be slightly offset due to parasitic capaci-
tance.
In a direct-conversion receiver, LO leakage to the RF
input connector is a major issue, since filtering of the
LO is impossible (the LO operates at the same frequen-
cy as the RF input). Observe the power-supply bypass
capacitor connections in the Pin Descriptiontable,
notably pins 3, 5, 12, and 21. Traces from these IC pins
to the bypass capacitors must be kept on the top side
of the board and as short as possible.
