MAX2105CWI 0 C to +70 C 28 SO 90 /64, /65

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1 ; Rev 2; 1/98 EVALUATION KIT MANUAL FOLWS DATA SHEET Direct-Conversion Tuner ICs for General Description The MAX212/MAX215 are low-cost direct-conversion tuner ICs designed for use in digital direct-broadcast satellite (DBS) television set-top box units. The direct-conversion architecture reduces system cost compared to devices with IF-based architectures. The MAX212/MAX215 directly tune L-band signals to baseband using a broadband I/Q downconverter. Operating frequency range spans from at least 95MHz to 215MHz. The ICs include a low-noise amplifier (LNA) with automatic gain control (AGC), two downconverter mixers, an oscillator buffer with 9 quadrature generator and prescaler, and baseband amplifiers. The MAX212 features an AGC range of 5dB, allowing input power levels as low as -69dBm. The MAX215 has a reduced AGC range of 41dB and accepts input power levels down to -6dBm. The reduced AGC range of the MAX215 allows the use of a high-gain external LNA to achieve a lower system noise figure (NF). Applications DBS Tuners DVB-Compliant DBS Tuners Cellular Base Stations Wireless Local Loop Broadband Systems LMDS Features Low-Cost Bipolar Design, Lowest Cost Architecture Operate from a Single +5V Supply 95MHz to 215MHz Input Frequency Range* On-Chip Quadrature Generator, Dual-Modulus Prescaler (/64, /65) Input Levels -69dBm to -19dBm per Carrier (MAX212) -6dBm to -19dBm per Carrier (MAX215) Over 5dB AGC Control Range (MAX212) Noise Figure = 13.2dB (MAX212); IP3 = 6.5dBm (at 145MHz) Automatic Baseband Offset Correction Easy Interface to MAX12/MAX13 Dual ADC and Popular Baseband ICs Ordering Information PART TEMP. RANGE PIN-PACKAGE MAX212CWI C to +7 C 28 SO MAX215CWI C to +7 C 28 SO Functional Diagram MAX212/MAX215 QOUT AGC RFIN RFIN IOUT Q I MAX212 MAX215 9 /64, /65 OFFSET CORRECTION QDC QDC IDC IDC PS PSOUT MOD Patents pending *Contact factory for MAX212/MAX215 versions with expanded frequency range. Maxim Integrated Products 1 For free samples & the latest literature: or phone For small orders, phone

2 MAX212/MAX215 ABSOLUTE MAXIMUM RATINGS to...-.5v to +7V RFIN to RFIN...±2V to...±2v AGC, MOD, RFIN, RFIN,, to...-.5v to ( +.5V) AGC Current....±3mA IDC to IDC, QDC to QDC...±2V IOUT or QOUT to Short-Circuit Duration...1sec PSOUT to Short-Circuit Duration...None 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. DC ELECTRICAL CHARACTERISTICS ( = +4.75V to +5.25V; = V; PS = ; AGC = 1.3V; MOD =.8V; P RFIN = OFF, f = MHz; P = -15dBm; IOUT, QOUT = open; T A = C to +7 C; unless otherwise noted.) SUPPLY PARAMETER Operating Supply Voltage Range Quiescent Supply Current CONTROL INPUTS, PRESCALER MOD Input Low Level MOD Input High Level MOD Input Bias Current AGC Input Bias Current AGC Input Bias Current IOUT, QOUT Common-Mode Voltage V V MOD MAX212 MAX215 CONDITIONS IDC, IDC, QDC, QDC to...-.5v to ( +.5V) Continuous Power Dissipation (T A = +7 C) SO (derate 12.5mW/ C above +7 C) W Operating Temperature Range... C to +7 C Junction Temperature C Storage Temperature Range C to +15 C Lead Temperature (soldering, 1sec)...+3 C.5V V AGC 4V 1V V AGC 4V MIN TYP MAX UNITS V ma V V µa µa V AC ELECTRICAL CHARACTERISTICS (MAX212 EV kit circuit (Figure 1); = +5V; PS = open; MOD = ; f RFIN = 215MHz; P RFIN = -19dBm; f = MHz; P = -15dBm driven single-ended into ; AGC set via servo loop for V IOUT = V QOUT =.5Vp-p; IOUT, QOUT drive AC-coupled 1Ω loads; 2kΩ from PSOUT to ; ; unless otherwise noted.) RF FRONT END PARAMETER RFIN Carrier Frequency Range RFIN Maximum Single-Carrier Input Power (Note 1) CONDITIONS Refers to single-carrier power generating V IOUT = V QOUT =.5Vp-p, 95MHz < f RFIN < 215MHz, 95MHz < f < 215MHz (Note 2) MIN TYP MAX UNITS MHz dbm RFIN Minimum Single-Carrier Input Power Refers to single-carrier power generating V IOUT = V QOUT =.5Vp-p, 95MHz < f RFIN < 215MHz, 95MHz < f < 215MHz (Note 2) MAX MAX215-6 dbm AGC Range.5V V AGC 4V 1V V AGC 4V MAX212 MAX db 2

3 AC ELECTRICAL CHARACTERISTICS (MAX212 EV kit circuit (Figure 1); = +5V; PS = open; MOD = ; f RFIN = 215MHz; P RFIN = -19dBm; f = MHz; P = -15dBm driven single-ended into ; AGC set via servo loop for V IOUT = V QOUT =.5Vp-p; IOUT, QOUT drive AC-coupled 1Ω loads; 2kΩ from PSOUT to ; ; unless otherwise noted.) RFIN Input Third-Order Intercept RFIN Input Second-Order Intercept Noise Figure PARAMETER Maximum Noise-Figure Variation with AGC Gain Setting RFIN Worst-Case VSWR across Band Maximum Power of Spurious Downconversion Products P RFIN = -19dBm per tone, AGC set via servo loop for V IOUT = V QOUT =.5Vp-p per tone, f1 RFIN = MHz, f2 RFIN = 1449MHz, f = 1451MHz P RFIN = -19dBm per tone, AGC set via servo loop for V IOUT = V QOUT =.5Vp-p per tone, f1 RFIN = 12MHz, f2 RFIN = 215MHz, f = 951MHz f RFIN = 1441MHz, f = 1451MHz f RFIN = 2141MHz, f = 2151MHz CONDITIONS Defined as NF/ Gain; for AGC range, defined as single-carrier power range of -69dBm to -59dBm (MAX212) or -6dBm to -5dBm (MAX215) MIN TYP MAX P RFIN = -69dBm MAX P RFIN = -6dBm MAX P RFIN = -69dBm MAX P RFIN = -6dBm MAX AGC = 4V, P RFIN set via servo MAX loop for V IOUT = V QOUT =.5Vp-p MAX f RFIN = 95MHz to 215MHz, 5Ω source MAX212 95MHz < f RFIN < 215MHz, 95MHz < f < 215MHz. Dominated by second-harmonic power causing downconversion of unwanted channel. Test conditions: f = 175.5MHz, f RFIN = 215MHz, P RFIN = -69dBm (MAX212) or -6dBm (MAX215) -.5 MAX : UNITS dbm dbm db db/db dbc MAX212/MAX215 P = -15dBm, 95MHz < f < 215MHz (Note 3) -49 Leakage at RFIN P = -15dBm, P = -15dBm (differentially driven), 95MHz < f < 215MHz (Note 3) -54 dbm 3

4 MAX212/MAX215 AC ELECTRICAL CHARACTERISTICS (continued) (MAX212 EV kit circuit (Figure 1); = +5V; PS = open; MOD = ; f RFIN = 215MHz; P RFIN = -19dBm; f = MHz; P = -15dBm driven single-ended into ; AGC set via servo loop for V IOUT = V QOUT =.5Vp-p; IOUT, QOUT drive AC-coupled 1Ω loads; 2kΩ from PSOUT to ; ; unless otherwise noted.) PARAMETER CONDITIONS OSCILLATOR BUFFER, QUADRATURE GENERATOR, PRESCALER Input Frequency Range (Note 1) Input Worst-Case VSWR over f = 95MHz to 215MHz, 5Ω source into Band MAX212 EV kit match circuit Input Power Level RFIN to Input Isolation IOUT, QOUT Phase Imbalance (Note 4) Refers to power level driven into, (differentially driven) (Notes 2, 4) (Notes 2, 5) 95MHz < f RFIN < 215MHz; 95MHz < f < 215MHz; P RFIN = -4dBm; f IOUT, f QOUT = 125kHz (Note 2) MIN TYP MAX : Worst-Case Additional Phase to +7 C (Notes 2 and 6) Imbalance Over Temperature to + C (Note 2) UNITS MHz dbm db degrees degrees IOUT, QOUT Amplitude Imbalance 95MHz < f RFIN < 215MHz; 95MHz < f < 215MHz; P RFIN = -4dBm; f IOUT, f QOUT = 125kHz (Note 2).5 db Prescaler Divide Ratio T A = C to +7 C MOD = low (Note 2) MOD = high Prescaler Output Swing at PSOUT 2kΩ 1pF load Prescaler Duty Cycle at PSOUT PSOUT load = 2kΩ 5pF (Note 3) BASEBAND AC CHARACTERISTICS IOUT, QOUT Clipping Level P RFIN = -5dBm; AGC = 4V, = 5.V Baseband Bandwidth (at IOUT, QOUT) At -3dB attenuation Vp-p % Vp-p MHz Baseband Gain Ripple (at IOUT, QOUT) 1kHz < (f IOUT, f QOUT ) < 25MHz, 95MHz < f RFIN < 215MHz, 95MHz < f < 215MHz (Notes 3, 7, 8) db Baseband Group Delay Ripple (at IOUT, QOUT) 1kHz < (f IOUT, f QOUT ) < 25MHz, 95MHz < f RFIN < 215MHz, 95MHz < f < 215MHz (Notes 3, 7, 8).45 ns 4

5 AC ELECTRICAL CHARACTERISTICS (continued) (MAX212 EV kit circuit (Figure 1); = +5V; PS = open; MOD = ; f RFIN = 215MHz; P RFIN = -19dBm; f = MHz; P = -15dBm driven single-ended into ; AGC set via servo loop for V IOUT = V QOUT =.5Vp-p; IOUT, QOUT drive AC-coupled 1Ω loads; 2kΩ from PSOUT to ; ; unless otherwise noted.) PARAMETER IOUT, QOUT Output Impedance Maximum IOUT to QOUT Output Impedance Difference Power-Supply Ripple Rejection (measured at IOUT, QOUT) (Note 3) (Note 3) CONDITIONS = 5V + 5mVp-p at 3kHz. Amplitude of 3kHz relative to 5mVp-p measured at IOUT, QOUT. Measured using MAX212 EV kit. MIN TYP MAX ±1 32 UNITS Ω Note 1: All specifications with guaranteed min/max limits are met within this frequency range. Contact factory for MAX212/MAX215 versions with expanded frequency range. Note 2: Guaranteed by production test and/or design and characterization. Note 3: Guaranteed by design and characterization. Note 4: IOUT, QOUT Phase and Amplitude Imbalance specifications are met within this power range. Note 5: Tested under two conditions: 1) Normal test: P RFIN = -2dBm, and 2) Overdrive test: P RFIN = -5dBm but AGC set via servo loop for V IOUT = V QOUT =.5Vp-p for P RFIN = -3dBm. Note 6: Negative numbers (-.1 ) indicate improvement in quadrature accuracy with increasing temperature. Note 7: Includes contribution from front-end gain tilt and delay variations produced by varying f RFIN by ±3MHz. Note 8: 1kHz minimum frequency determined by.22µf offset-correction capacitors. Different value capacitors yield proportionally different low-frequency cutoffs. Group delay at low frequencies will also be affected. See Applications Information section. Ω db MAX212/MAX215 Typical Operating Characteristics (MAX212 EV kit circuit (Figure 1), = 5V, PS = open, MOD =, f RFIN = 215MHz, P RFIN = -19dBm, f = MHz, P = -15dBm driven single-ended into, AGC set via servo loop for V IOUT = V QOUT =.5Vp-p, IOUT, QOUT drive AC-coupled 1Ω loads, 2kΩ from PSOUT to,, unless otherwise noted.) SUPPLY CURRENT (ma) SUPPLY CURRENT vs. SUPPLY VOLTAGE PS = (PRESCALER ENABLED) T A = +7 C T A = C MAX212/5-1 SINGLE-CARRIER POWER FOR.5Vp-p BASEBAND LEVEL (dbm) MAX212 AGC RANGE vs. FREQUENCY AGC = 1V T A = +7 C AGC RANGE T A = +7 C T A = C T A = C AGC = 4V MAX212/5-2 SINGLE CARRIER POWER FOR.5Vp-p BASEBAND LEVEL (dbm) MAX215 AGC RANGE vs. FREQUENCY T A = C AGC = 1V AGC = 4V T A = +7 C T A = +7 C T A = C MAX212/5-1insert SUPPLY VOLTAGE (V) RFIN FREQUENCY (GHz) RFIN FREQUENCY (GHz) 5

6 MAX212/MAX215 Typical Operating Characteristics (continued) (MAX212 EV kit circuit (Figure 1), = 5V, PS = open, MOD =, f RFIN = 215MHz, P RFIN = -19dBm, f = MHz, P = -15dBm driven single-ended into, AGC set via servo loop for V IOUT = V QOUT =.5Vp-p, IOUT, QOUT drive AC-coupled 1Ω loads, 2kΩ from PSOUT to,, unless otherwise noted.) SINGLE-CARRIER INPUT LEVEL FOR.5Vp-p BASEBAND LEVEL (dbm) MAX212 CARRIER LEVEL vs. AGC VOLTAGE T A = C AGC VOLTAGE (V) AGC SET FOR I OUT Q OUT =.5Vp-p T A = +7 C MAX212/5-3 SINGLE-CARRIER POWER FOR.5Vp-p BASEBAND LEVEL (dbm) MAX215 CARRIER LEVEL vs. AGC VOLTAGE AGC SET FOR I OUT, Q OUT =.5Vp-p T A = +7 C T A = C AGC VOLTAGE (V) MAX212/5-2insert NOISE FIGURE (db) MAX212 NOISE FIGURE vs. FREQUENCY T A = +7 C T A = C AGC SET FOR P RFIN = -69dBm FREQUENCY (GHz) MAX212/5-4 NOISE FIGURE (db) NOISE FIGURE (db) MAX215 NOISE FIGURE vs. FREQUENCY +25 C NF (db) +7 C NF (db) MAX212 NOISE FIGURE vs. INPUT CARRIER LEVEL T A = +7 C T A = C C NF (db) 14.7 AGC SET FOR P RFIN = -6dBm FREQUENCY (MHz) f = 1451MHz RFIN CARRIER LEVEL (dbm) MAX212/5-3insert MAX212/5-6 NOISE FIGURE (db) NOISE FIGURE (db) MAX212 NOISE FIGURE vs. INPUT CARRIER LEVEL T A = +7 C T A = C f = 2151MHz RFIN CARRIER LEVEL (dbm) MAX215 NOISE FIGURE vs. INPUT CARRIER LEVEL T A = +7 C T A = C f = 1441MHz RFIN CARRIER LEVEL (dbm) MAX212/5-5 MAX212/5-5insert NOISE FIGURE (db) INPUT IP3 (dbm) RFIN CARRIER LEVEL (dbm) MAX215 NOISE FIGURE vs. INPUT CARRIER LEVEL INPUT-REFERRED IP3 vs. FREQUENCY T A = +7 C T A = +7 C T A = C T A = C f1 = f - 2MHz f2 = f - 2.9MHz P RFIN = -19dBm PER TONE AGC SET VIA SERVO OP FOR.5Vp-p PER TONE FREQUENCY (GHz) f = 2141MHz MAX212/5-7 MAX212/5-4insert 6

7 Typical Operating Characteristics (continued) (MAX212 EV kit circuit (Figure 1), = 5V, PS = open, MOD =, f RFIN = 215MHz, P RFIN = -19dBm, f = MHz, P = -15dBm driven single-ended into, AGC set via servo loop for V IOUT = V QOUT =.5Vp-p, IOUT, QOUT drive AC-coupled 1Ω loads, 2kΩ from PSOUT to,, unless otherwise noted.) SERIES IMPEDANCE (Ω) IM3 LEVEL (dbc) PORT IMPEDANCE vs. FREQUENCY (UNMATCHED) REAL IMAGINARY FREQUENCY (GHz) IM3 LEVELS vs. INPUT CARRIERS POWER LEVEL SINGLE INPUT CARRIER LEVEL (dbm) POWER AT RFIN (dbm) T A = C T A = +7 C f1 = MHz f2 = 1449MHz f = 1451MHz AGC SET VIA SERVO OP FOR.5Vp-p PER TONE MAX212/5-8 MAX212/5-11 IM3 LEVEL (dbc) SERIES IMPEDANCE (Ω) LEAKAGE AT RFIN vs. FREQUENCY (DIFFERENTIAL DRIVE) AGC SET FOR P RFIN = -69dBm P REFERS TO POWER INTO AND P = -15dBm P = -1dBm P = -5dBm IM3 LEVELS vs. INPUT CARRIER POWER LEVEL T A = C T A = +7 C f1 = MHz f2 = 2149MHz f = 2151MHz AGC SET VIA SERVO OP FOR.5V PER TONE SINGLE INPUT CARRIER LEVEL (dbm) RFIN PORT IMPEDANCE vs. FREQUENCY FREQUENCY (GHz) MAX212/5-14 REAL IMAGINARY MATCHED PER EV KIT CIRCUIT SPURIOUS SIGNAL LEVEL NORMALIZED TO LEVEL WHEN FRFIN = 174.5MHz (dbc) MAX212/5-9 MAX212/5-12 SERIES IMPEDANCE (Ω) POWER AT RFIN (dbm) PORT IMPEDANCE vs. FREQUENCY MATCHED: MAX212 TYPICAL OPERATING CIRCUIT REAL FREQUENCY (GHz) IMAGINARY LEAKAGE AT RFIN vs. FREQUENCY (SINGLE-ENDED DRIVE) P = -5dBm P = -15dBm P = -1dBm FREQUENCY (GHz) SPURIOUS DOWNCONVERSION DUE TO INTERNALLY GENERATED 2ND HARMONIC f = 175.5MHz f RFIN = 215MHz P RFIN = -69dBm DRIVEN SINGLE ENDED, DRIVEN DIFFERENTIAL (P = -15dBm, P = -15dBm) MAX212/5-15 MAX212/5-1 MAX212/5-13 MAX212/MAX FREQUENCY (GHz) POWER (dbm) 7

8 MAX212/MAX215 Typical Operating Characteristics (continued) (MAX212 EV kit circuit (Figure 1), = 5V, PS = open, MOD =, f RFIN = 215MHz, P RFIN = -19dBm, f = MHz, P = -15dBm driven single-ended into, AGC set via servo loop for V IOUT = V QOUT =.5Vp-p, IOUT, QOUT drive AC-coupled 1Ω loads, 2kΩ from PSOUT to,, unless otherwise noted.) QOUT PHASE RELATIVE TO IOUT PHASE (degrees) QUADRATURE PHASE IMBALANCE vs. FREQUENCY f = f RFIN + 125kHz P RFIN = -4dBm P = -15dBm T A = +7 C T A = C RFIN FREQUENCY (GHz) MAX212/5-16 QOUT LEVEL RELATIVE TO IOUT LEVEL (db) QUADRATURE GAIN IMBALANCE vs. FREQUENCY f = f RFIN + 125kHz P RFIN = -4dBm P = -15dBm T A = C T A = +7 C RFIN FREQUENCY (GHz) MAX212/5-17 BASEBAND GAIN (db) BASEBAND GAIN FLATNESS vs. FREQUENCY FREQUENCY (MHz) T A = +7 C T A = C MAX212/5-18 BASEBAND GROUP DELAY (ns) BASEBAND GROUP DELAY FLATNESS vs. FREQUENCY T A = C T A = +7 C FREQUENCY (MHz) MAX212/5-19 IM LEVELS (dbc) BASEBAND IM LEVELS IM2 IM3 f1 = MHz f2 = 1449MHz f = 1451MHz P RFIN = -4dBm PER TONE BASEBAND LEVELS, PER TONE (Vp-p) MAX212/5-2 BASEBAND OUTPUT IMPEDANCE (Ω) BASEBAND OUTPUT IMPEDANCE vs. FREQUENCY FREQUENCY (MHz) MAX212/5-21 8

9 PIN 1 2 3, , 11, 19, 24 1 NAME IOUT RFIN RFIN AGC RF Ground. Connect directly to the ground plane. FUNCTION Pin Description Baseband +5V Supply. Bypass with a 1pF capacitor from this pin to pin 3 (), as close to the IC as possible. Connect an additional.1µf capacitor in parallel with the 1pF capacitor (placement less critical). I Channel Baseband Output Baseband Ground RF +5V Supply. Bypass with a 22pF capacitor from this pin to pin 11 (), as close to the IC as possible. Ground (substrate) RF +5V Supply. Bypass with a 22pF capacitor from this pin to pin 9 (), as close to the IC as possible. RF Noninverting Input. Couple through a 22pF capacitor directly to a 5Ω signal source. RF Inverting Input. Connect to a 22pF series capacitor and a 51Ω resistor to ground. Automatic Gain-Control Input. Bypass this pin with a 1pF capacitor close to the pin, to minimize coupling. MAX212/MAX QOUT Q Channel Baseband Output 14 Baseband +5V Supply. Bypass with a 1pF capacitor from this pin to pin 12 (), as close to the IC as possible. Connect an additional.1µf capacitor in parallel with the 1pF capacitor (placement less critical). 15 QDC Q Channel Offset-Correction Noninverting Input. Connect a.22µf (typ) capacitor between QDC and QDC. This capacitor must be placed as close to the IC as possible (see Layout Considerations section). 16 QDC Q Channel Offset-Correction Inverting Input. Connect a.22µf (typ) capacitor between QDC and QDC. This capacitor must be placed as close to the IC as possible (see Layout Considerations section). 17 IDC I Channel Offset-Correction Inverting Input. Connect a.22µf (typ) capacitor between IDC and IDC. This capacitor must be placed as close to the IC as possible (see Layout Considerations section). 18 IDC I Channel Offset-Correction Noninverting Input. Connect a.22µf (typ) capacitor between IDC and IDC. This capacitor must be placed as close to the IC as possible (see Layout Considerations section). 2 RF +5V Supply. Bypass with a 1pF capacitor from this pin to pin 19 () as close to the IC as possible. 21 Local-Oscillator Complementary Input Port (Figure 1) 22 Local-Oscillator Input Port (Figure 1) 23 RF +5V Supply. Bypass with a 1pF capacitor from this pin to pin 24 () as close to the IC as possible. 25 PS Prescaler Ground. To disable the prescaler, leave this pin open. 26 PSOUT Prescaler Output. Drives CMOS load. Connect 2kΩ from this pin to (if the prescaler is enabled). 27 MOD Prescaler Modulus Control. Leave open when the prescaler is disabled. 28 Prescaler +5V Supply. Must be connected even if the prescaler is disabled. Bypass with a 1pF capacitor. 9

10 MAX212/MAX215 1Ω AD RF INPUT (5Ω SOURCE) 47µF.1µF 22pF 22pF.1µF 22pF 1pF IOUT RFIN RFIN MAX212 MAX215 MOD PSOUT PS pF 1pF 1pF 22pF 22Ω 2kΩ MODULUS CONTROL PRESCALER OUTPUT INPUT (5Ω SOURCE) 51Ω 22pF Ω 33Ω AGC CONTROL 1 AGC 19 1pF 1pF 11 IDC 18 47µF 12 IDC 17.22µF 1Ω AD.1µF.1µF 1pF QOUT QDC QDC µF Figure 1. Typical Operating Circuit Detailed Description The MAX212/MAX215 down-convert signals in the range 95MHz to 215MHz directly to baseband I/Q signals. They are targeted for digital DBS tuner applications where a direct downconversion provides a cost savings over prior-art, multiple-conversion approaches. However, the MAX212/MAX215 are applicable to any system requiring a broadband I/Q downconversion. Internally, the MAX212 and MAX215 consist of a broadband front-end variable gain stage, a quadrature downconverter, an oscillator buffer, high-linearity I and Q baseband amplifiers, and offset correction amplifiers. The MAX212 features a front-end AGC dynamic range of over 5dB, while the MAX215 provides a front-end AGC dynamic range of over 41dB. Specifically, the AGC control can be adjusted so that a sine wave at RFIN ranging in power from -69dBm to -19dBm (MAX212) or -6dBm to -19dBm (MAX215) will produce a sine wave at IOUT and QOUT at 5mVp-p levels. The noise figure is lowest when the AGC is at its maximum gain setting (see Typical Operating Characteristics). The VSWR at RFIN is unaffected by the AGC setting. The local-oscillator () buffer accepts an external signal at,, and internally limits the signal to provide a consistent on-chip level. The input drive level should be maintained within the specified limits (see Applications Information section). 1

11 LNB KU BAND 75Ω CABLE 95MHz to 215MHz The quadrature downconverter follows the front-end AGC. Two mixers are driven by the previous stage AGC amplifier output. The mixer ports are fed with the two signals, which are 9 apart in phase. These quadrature signals are generated on-chip using the signal from the buffer. The resulting I/Q baseband signals are fed through separate I and Q channel baseband amplifiers. Robust output stages drive IOUT and QOUT. The outputs are capable of driving lowpass filters with 1Ω characteristic impedance (that is, the equivalent of an AC-coupled, 1Ω load). The baseband -3dB output bandwidth is over 9MHz. Applications Information Front-End Tuner Circuitry for DBS Tuners In a typical application, the signal path ahead of the MAX212/MAX215 will include a discrete LNA/buffer and a PIN-diode attenuator. Alternatively, a dual-gate F-CONNECTOR FOR 2nd SET-TOP BOX F-CONNECTOR INPUT MAX212/MAX215 OR RFIN AGC IOUT.1µF R S L1 L2 L3 C1 C2 C3 C4.1µF ADC AGC EXTERNAL VCO TANK OR RFIN OFFSET CORRECTION 9 DIV MAX212 MAX215 QOUT.1µF BASEBAND LP FILTERS R S L1 L2 L3 C1 C2 C3 C4 R L.1µF R L (OPTIONAL GAIN) MAX12 MAX13 ADC DSP: QPSK DEMOD TSA555 OR EQUIV. IDC IDC QDC QDC PSOUT MOD Figure 2. Typical Application 11

12 MAX212/MAX215 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 leakage requirements. The PIN attenuator is typically controlled by the same voltage as the MAX212/MAX215 AGC control pin so that, overall, a single AGC line from the baseband processor can control the entire tuner. In some applications, a varactor-tuned preselection bandpass filter is added between the discrete LNA and the MAX212/MAX215. This is usually required only for very high-linearity tuners, such as those designed for single channel-per-carrier (low-data-rate) applications. The filter provides a means of broadly filtering adjacent interferers, thus improving the tuner s intermodulation performance. Additionally, the filter removes the RF interference at twice the frequency, which would otherwise add to cochannel interference (the MAX212/MAX215 alone reject this carrier to typically -32.3dBc). External Oscillator Since the MAX212/MAX215 are direct-conversion receivers, the external must tune to the same frequencies as the desired RF input signals. The MAX212/MAX215 oscillator input port (, ) accepts either a single-ended or differential (balanced) signal. A differential offers reduced leakage to the RFIN port, as well as lower spurious downconversion levels of RF signals, which are at twice the frequency. Refer to Figure 3 for differential connections. For best performance, ensure that the and traces are symmetrical. The drive levels should be maintained to within the specified limits. If the drive falls below the specified range, quadrature performance may be affected. Driving above the specified limits will cause a higher leakage level at RFIN; this may be acceptable in some applications. The MAX212/MAX215 offset-correction loop can withstand leakage levels corresponding to at least dbm of input power drive. Prescaler Typical stand-alone tuner applications will not use the MAX212/MAX215 prescaler function, but instead use a commercial synthesizer IC such as the Philips TSA555, which has an internal prescaler. To disable the MAX212/MAX215 prescaler, disconnect the PS pin (leave open). The prescaler will cause an output spur in the baseband spectrum, to a level of about -2dBc (referred to 5mVp-p baseband output level) that may land within the desired signal bandwidth in some applications. 22Ω 22Ω 56Ω 56Ω 22pF 22pF POWER: -15dBm TO -5dBm, POWER INTO,., DRIVEN DIFFERENTIALLY Figure 3. Differential Drive MAX212 MAX215 To use the MAX212/MAX215 prescaler, connect the PS pin to ground. In some applications, the prescaler may be toggled on and off using a MOSFET to switch PS to ground. PS should be forced to within 1mV of ground, and the MOSFET must be capable of sinking 15mA. PSOUT is capable of driving a typical CMOS load of 1kΩ in parallel with 5pF. A 2kΩ pull-down resistor must be connected from PSOUT to. The prescaler requires a stable level at the MOD pin 12ns before the falling edge of PREOUT to assert the desired modulus. The level at MOD must remain static until 3ns after this falling edge. Baseband Amplifiers The MAX212/MAX215 baseband amplifiers provide over 2Vp-p swing at IOUT and QOUT, and are capable of driving 1Ω. IOUT and QOUT must be AC-coupled to any lowpass filters. In a typical application, IOUT and QOUT drive a 5th or 7th-order lowpass filter for ADC anti-aliasing purposes (see the Systems Considerations: Lowpass Filters in Direct-Conversion Tuners section). After the filters, in some cases, additional gain may be required. This can be accomplished with a pair of videospeed op amps, such as the MAX4216 dual-video op amp. Alternatively, the MAX12/MAX13 dual ADC has built-in gain ahead of the ADCs, digitizing levels as low as 125mVp-p. Contact Maxim for more information about the MAX4216 or the MAX12/MAX

13 Offset Correction The internal offset-correction amplifiers remove the DC offsets present in the baseband amplifiers. The offsetcorrection loop effectively AC-couples the baseband signal path, yielding a -3dB highpass corner frequency according to the following: f-3db = 1/CDC (µf) where CDC is the value of the capacitors, in microfarads, across QDC, QDC and IDC, IDC. For applications where the DC information must be maintained through the signal path, the offset correction can be disabled by connecting QDC, QDC, IDC, and IDC directly to ground. Disabling the offset correction will effectively limit the input dynamic range of the MAX212/MAX215. Typical input dynamic range will be approximately -45dBm to -19dBm for single-ended drive, and -55dBm to -19dBm for differential drive. 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. In a direct-conversion receiver, leakage to the RF input connector is a major issue, since filtering of the is impossible (the operates at the same frequency as the RF input). The external VCO section should be housed in a separate shielded compartment, if possible. Use of a differential (balanced) will dramatically reduce leakage. Also, the use of coplanar, waveguide transmission-line structures reduces leakage (used on the MAX212 EV kit). Observe the power-supply bypass capacitor connections in the Pin Description table, notably pins 1, 3, 4, 6, 9, 11, 12, 14, 19, 2, 23, and 24. Traces from these IC pins to the bypass capacitors must be kept to an absolute minimum. Where possible, make these connections on the top side of the board. The MAX212 EV kit includes ferrite beads in series with power-supply leads. The beads may not be required for all applications. MAX212/MAX215 Table 1. Suggested Component Values for Discrete Lowpass Filters (.1dB Ripple Chebyshev Type) ADC SAMPLING RATE (Msps) FILTER TYPE R S (Ω) C1 (pf) L1 (nh) C2 (pf) L2 (nh) C3 (pf) L3 (nh) C4 (pf) R L (kω) 4.1dB Chebyshev, f C = 2MHz dB Chebyshev, f C = 3MHz dB Chebyshev, f C = 45MHz Note: Suggested types: Inductors: Coilcraft 18CS, tolerance = ±5%; Capacitors: use tolerance = ±2%. Refer to Figure 2 for circuit diagram. 13

14 MAX212/MAX215 Power-Supply Sequencing The MAX212/MAX215 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. Leaving PS open will disable the prescaler function and, in this state, the prescaler will not dissipate any power. I Systems Consideration: Lowpass Filters in Direct-Conversion Tuners Typically, a 5th or 7th-order L-C lowpass filter is used for anti-aliasing the ADCs following the MAX212. Figures 4 and 5 describe typical filtering requirements. Table 1 offers suggested component values for these lowpass filters. Chip Information TRANSISTOR COUNT: 1852 SUBSTRATE CONNECTED TO MAX212 MAX215 ANAG LP FILTERS ADCs MATCHED FILTERS Q DIGITAL SIGNAL PROCESSING Figure 4. I, Q Signal Path 14

15 AT SIGNAL POINT NO. 1 AT SIGNAL POINT NO. 2 DESIRED dbc CHANNEL (2Msps) -3 1 DATA NYQUIST DESIRED dbc CHANNEL (2Msps) -3 1 α =.2 NYQUIST FOR ADC TRANSPONDER SPACING = MHz WPASS FILTER RESPONSE TRANSPONDER BW = 24MHz UNDESIRED ADJACENT CHANNEL ADC SAMPLING MHz MHz MAX212/MAX215 PASSBAND FILTER REQUIREMENTS: (1) <2% OF BAUD PERIOD DELAY RIPPLE (2) <.1dB GAIN RIPPLE TRANSITION BAND FILTER REQUIREMENTS: < 2dB GAIN RIPPLE FILTER CUTOFF ADC SAMPLING AT SIGNAL POINT NO.3 DESIRED dbc CHANNEL (2Msps) -3 1 ADJ CHANNEL FOLDOVER MHz ADC NYQUIST ADC SAMPLING AT SIGNAL POINT NO.4 DIGITAL MATCHED FILTER DESIRED dbc CHANNEL (2Msps) MHz ADC SAMPLING Figure 5. Lowpass Filtering Example. Note: Data Rate = 4Mbps, Transponder BW = 24MHz, Transponder Spacing = 29.16MHz, Nyquist Filter: α =.2 15

16 MAX212/MAX215 Package Information SOICW.EPS 16

17 This datasheet has been download from: Datasheets for electronics components.