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General Description

The MAX2102/MAX2105

†

are low-cost direct-conver-

sion tuner ICs designed for use in digital direct-broad-

cast satellite (DBS) television set-top box units. The

direct-conversion architecture reduces system cost

compared to devices with IF-based architectures.

The MAX2102/MAX2105 directly tune L-band signals to

baseband using a broadband I/Q downconverter.

Operating frequency range spans from at least 950MHz

to 2150MHz.

The ICs include a low-noise amplifier (LNA) with auto-

matic gain control (AGC), two downconverter mixers,

an oscillator buffer with 90° quadrature generator and

prescaler, and baseband amplifiers.

The MAX2102 features an AGC range of 50dB, allowing

input power levels as low as -69dBm. The MAX2105

has a reduced AGC range of 41dB and accepts input

power levels down to -60dBm. The reduced AGC range

of the MAX2105 allows the use of a high-gain external

LNA to achieve a lower system noise figure (NF).

________________________Applications

DBS Tuners Wireless Local Loop

DVB-Compliant DBS Tuners Broadband Systems

Cellular Base Stations LMDS

____________________________Features

♦ Low-Cost Bipolar Design, Lowest Cost

Architecture

♦ Operate from a Single +5V Supply

♦ 950MHz to 2150MHz Input Frequency Range*

♦ On-Chip Quadrature Generator, Dual-Modulus

Prescaler (/64, /65)

♦ Input Levels

-69dBm to -19dBm per Carrier (MAX2102)

-60dBm to -19dBm per Carrier (MAX2105)

♦ Over 50dB AGC Control Range (MAX2102)

♦ Noise Figure = 13.2dB (MAX2102);

IP3 = 6.5dBm (at 1450MHz)

♦ Automatic Baseband Offset Correction

♦ Easy Interface to MAX1002/MAX1003 Dual ADC

and Popular Baseband ICs

MAX2102/MAX2105

Direct-Conversion Tuner ICs for

Digital DBS Applications

________________________________________________________________

Maxim Integrated Products

MAX2102

MAX2105

QOUT GND GND AGC GND RFIN V

GND V

GND IOUT V

OFFSET CORRECTION

/64, /65

90°

0°

RFIN

QDC

IDC IDC GND V

LO V

GND PSGND PSOUT MOD V

LOQDC

13121110987654321

15 16 17 18 19 20 21 22

24 25 26 27 28

Functional Diagram

19-1256; Rev 2; 10/98

PART

MAX2102CWI

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

28 SO

EVALUATION KIT MANUAL

FOLLOWS DATA SHEET

Ordering Information

†

Patents pending

Contact factory for MAX2102/MAX2105 versions with expanded frequency range.

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.

For small orders, phone 1-800-835-8769.

MAX2105CWI

0°C to +70°C 28 SO

Summary of content (16 pages)

PAGE 1
9-1256; Rev 2; 10/98 NUAL KIT MA ATION U EET L H A S V E S DATA W O L L FO Direct-Conversion Tuner ICs for Digital DBS Applications The MAX2102 features an AGC range of 50dB, allowing input power levels as low as -69dBm. The MAX2105 has a reduced AGC range of 41dB and accepts input power levels down to -60dBm. The reduced AGC range of the MAX2105 allows the use of a high-gain external LNA to achieve a lower system noise figure (NF).
PAGE 2
MAX2102/MAX2105 Direct-Conversion Tuner ICs for Digital DBS Applications ABSOLUTE MAXIMUM RATINGS VCC to GND ..............................................................-0.5V to +7V RFIN to RFIN ..........................................................................±2V LO to LO ................................................................................±2V AGC, MOD, RFIN, RFIN, LO, LO to GND.....-0.5V to (VCC + 0.5V) AGC Current. ....................................................................
PAGE 3
Direct-Conversion Tuner ICs for Digital DBS Applications (MAX2102 EV kit circuit (Figure 1); V CC = +5V; PSGND = open; MOD = GND; f RFIN = 2150MHz; P RFIN = -19dBm; f LO = 2150.125MHz; PLO = -15dBm driven single-ended into LO; AGC set via servo loop for VIOUT = VQOUT = 0.5Vp-p; IOUT, QOUT drive AC-coupled 100Ω loads; 2kΩ from PSOUT to GND; TA = +25°C; unless otherwise noted.
PAGE 4
MAX2102/MAX2105 Direct-Conversion Tuner ICs for Digital DBS Applications AC ELECTRICAL CHARACTERISTICS (continued) (MAX2102 EV kit circuit (Figure 1); V CC = +5V; PSGND = open; MOD = GND; f RFIN = 2150MHz; P RFIN = -19dBm; f LO = 2150.125MHz; PLO = -15dBm driven single-ended into LO; AGC set via servo loop for VIOUT = VQOUT = 0.5Vp-p; IOUT, QOUT drive AC-coupled 100Ω loads; 2kΩ from PSOUT to GND; TA = +25°C; unless otherwise noted.
PAGE 5
Direct-Conversion Tuner ICs for Digital DBS Applications (MAX2102 EV kit circuit (Figure 1); V CC = +5V; PSGND = open; MOD = GND; f RFIN = 2150MHz; P RFIN = -19dBm; f LO = 2150.125MHz; PLO = -15dBm driven single-ended into LO; AGC set via servo loop for VIOUT = VQOUT = 0.5Vp-p; IOUT, QOUT drive AC-coupled 100Ω loads; 2kΩ from PSOUT to GND; TA = +25°C; unless otherwise noted.) TYP MAX UNITS IOUT, QOUT Output Impedance PARAMETER (Note 3) CONDITIONS MIN 4.
PAGE 6
Typical Operating Characteristics (continued) (MAX2102 EV kit circuit (Figure 1), VCC = 5V, PSGND = open, MOD = GND, fRFIN = 2150MHz, PRFIN = -19dBm, fLO = 2150.125MHz, PLO = -15dBm driven single-ended into LO, AGC set via servo loop for VIOUT = VQOUT = 0.5Vp-p, IOUT, QOUT drive AC-coupled 100Ω loads, 2kΩ from PSOUT to GND, TA = +25°C, unless otherwise noted.) TA = +25°C -60 TA = 0°C -20 -30 TA = +70°C -40 TA = +25°C -50 TA = 0°C 1.6 2.0 2.4 +70°C NF (dB) 0.8 4.0 15.7 +25°C NF (dB) 15.3 15.
PAGE 7
Direct-Conversion Tuner ICs for Digital DBS Applications IMAGINARY -50 -100 -150 TA = 0°C TA = +25°C 30 TA = +70°C 20 f1 = 2148.1MHz f2 = 2149MHz fLO = 2151MHz AGC SET VIA SERVO LOOP FOR 0.5V PER TONE 10 -200 0 1.1 1.4 1.7 2.0 2.3 -10 -15 -20 -25 -30 -35 40 IMAGINARY 20 0 -20 -40 0.8 -40 1.1 1.4 1.7 2.0 2.3 FREQUENCY (GHz) IM3 LEVELS vs. INPUT CARRIERS POWER LEVEL RFIN PORT IMPEDANCE vs. FREQUENCY LO LEAKAGE AT RFIN vs.
PAGE 8
Typical Operating Characteristics (continued) (MAX2102 EV kit circuit (Figure 1), VCC = 5V, PSGND = open, MOD = GND, fRFIN = 2150MHz, PRFIN = -19dBm, fLO = 2150.125MHz, PLO = -15dBm driven single-ended into LO, AGC set via servo loop for VIOUT = VQOUT = 0.5Vp-p, IOUT, QOUT drive AC-coupled 100Ω loads, 2kΩ from PSOUT to GND, TA = +25°C, unless otherwise noted.) QUADRATURE GAIN IMBALANCE vs. FREQUENCY 91 90 TA = +70°C TA = +25°C 89 88 87 0.3 fLO = fRFIN + 125kHz PRFIN = -40dBm PLO = -15dBm 0.2 0.1 0 -0.
PAGE 9
Direct-Conversion Tuner ICs for Digital DBS Applications PIN NAME FUNCTION 1 VCC Baseband +5V Supply. Bypass with a 10pF capacitor from this pin to pin 3 (GND), as close to the IC as possible. Connect an additional 0.1µF capacitor in parallel with the 10pF capacitor (placement less critical). 2 IOUT I Channel Baseband Output 3, 12 GND Baseband Ground 4 VCC RF +5V Supply. Bypass with a 22pF capacitor from this pin to pin 11 (GND), as close to the IC as possible.
PAGE 10
MAX2102/MAX2105 Direct-Conversion Tuner ICs for Digital DBS Applications VCC VCC 1 47µF 0.1µF 10pF 2 VCC VCC 1000pF IOUT MOD 100Ω LOAD 3 0.
PAGE 11
Direct-Conversion Tuner ICs for Digital DBS Applications istic impedance (that is, the equivalent of an AC-coupled, 100Ω load). The baseband -3dB output bandwidth is over 90MHz. __________Applications Information Front-End Tuner Circuitry for DBS Tuners The resulting I/Q baseband signals are fed through separate I and Q channel baseband amplifiers. Robust output stages drive IOUT and QOUT.
PAGE 12
MAX2102/MAX2105 Direct-Conversion Tuner ICs for Digital DBS Applications GaAsFET can serve this function. This circuitry is usually required in order to meet system noise-figure requirements, may provide a buffered F-connector output, and may also be required to meet stringent LO leakage requirements. The PIN attenuator is typically controlled by the same voltage as the MAX2102/MAX2105 AGC control pin so that, overall, a single AGC line from the baseband processor can control the entire tuner.
PAGE 13
Direct-Conversion Tuner ICs for Digital DBS Applications Layout Considerations Observe standard RF layout rules. A ground plane is essential; when connecting areas of ground plane between layers, use vias liberally. Remove the ground plane under the external VCO area to reduce parasitic capacitance. If a ground plane is used under the lowpass filters, note that the filter shape may be slightly offset due to parasitic capacitance.
PAGE 14
MAX2102/MAX2105 Direct-Conversion Tuner ICs for Digital DBS Applications Power-Supply Sequencing The MAX2102/MAX2105 have several +5V supply pins. The supply layout should be in a star format, with a bypass capacitor that dominates the rise time of the supply at the center of the star, to ensure that all pins see approximately the same voltage during power-up. The prescaler VCC (pin 28) must be connected to the same VCC as the other VCC pins, even if the prescaler is not used.
PAGE 15
Direct-Conversion Tuner ICs for Digital DBS Applications MAX2102/MAX2105 TRANSPONDER BW = 24MHz 0 AT SIGNAL POINT NO. 1 DESIRED CHANNEL (20Msps) dBc UNDESIRED ADJACENT CHANNEL -30 0 10 12 17.16 20 29.16 40 41.16 MHz α = 0.2 DATA NYQUIST ADC SAMPLING NYQUIST FOR ADC TRANSPONDER SPACING = 29.16 MHz LOWPASS FILTER RESPONSE 0 AT SIGNAL POINT NO. 2 DESIRED CHANNEL (20Msps) dBc -30 0 10 12 17.
PAGE 16
________________________________________________________Package Information SOICW.