19-1764; Rev 2; 6/05 Low-Noise, High-Linearity Broadband Amplifier Features The MAX3524 broadband amplifier is designed specifically for cable television receiver and cable modem applications. The MAX3524 is a single-ended input, differential-output low-noise amplifier (LNA) that offers 15dB of gain. It operates from a +4.75V to +5.25V single supply from 44MHz to 880MHz. The MAX3524 includes an operational amplifier that is used to control an off-chip PIN attenuator circuit at the input of the LNA. The attenuator is typically used to regulate the input signal to a value that maintains high linearity for large signals. The MAX3524 is available in a 10-pin µMAX® package with an exposed paddle (EP) and operates in the extended temperature range (-40°C to +85°C). ♦ Single-Ended Input, Differential Output ♦ +4.75V to +5.25V Single-Supply Operation ♦ Broadband Operation: 44MHz to 880MHz ♦ Low Noise Figure: 4.2dB ♦ High Linearity: IIP2 (42dBm), IIP3(14dBm) ♦ Voltage Gain: 15dB ♦ Independent On-Chip Op Amp Ordering Information Applications Cable Modems TEMP RANGE PIN-PACKAGE Cable Set-Top Boxes MAX3524EVB PART -40°C to +85°C 10 µMAX-EP* Broadband Amplifiers MAX3524EVB+ -40°C to +85°C 10 µMAX-EP* CATV Infrastructures *EP = Exposed paddle. +Denotes lead-free package. µMAX is a registered trademark of Maxim Integrated Products, Inc. Typical Application Circuit VCC = 5V 10µF INPUT: 44-880MHz 75Ω TO 2kΩ 1 0.1µF 2 PIN ATTENUATOR RFOUT- 10 VCC RFIN MAX3524 VCC 0.1µF L1 = 0.5nH TO 1nH CL < 1.8pF OUTPUT TO TUNER (DIFFERENTIAL DRIVE) 9 VCC = 5V 10µF 10nF 0.1µF 3 4 8 RFGND L2 = 0.5nH TO 1nH RFOUT+ OPIN+ OPOUT 7 0.1µF R1 3kΩ FROM DEMOD IC TO CONTROL PIN ATTENUATOR OP AMP D2 CMDSH-3 5 OPIN- BIAS GND R2 3kΩ 6 LBIAS = 680nH RBIAS = 5.9Ω * D1 CMDSH-3 *EXPOSED PADDLE Pin Configuration appears at end of data sheet. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX3524 General Description MAX3524 Low-Noise, High-Linearity Broadband Amplifier ABSOLUTE MAXIMUM RATINGS VCC to GND ...........................................................-0.3V to +7.0V RFIN ....................................................................................+2.0V PRFIN ...................................................................................0dBm RBIAS (MINIMUM) .......................................................................5Ω RFOUT+, RFOUT-, OPIN-, OPIN+, OPOUT...-0.3V to (VCC + 0.3V) RFOUT+, RFOUT- Short-Circuit Duration ...............................10s Continuous Power Dissipation (TA = +70°C) 10-Pin µMAX (derate 10.3mW/°C above +70°C) .........825mW Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range .............................-65°C to +150°C Junction Temperature ......................................................+150°C Lead Temperature (soldering, 10s) .................................+300°C 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. CAUTION! ESD SENSITIVE DEVICE DC ELECTRICAL CHARACTERISTICS (Typical Application Circuit, VCC = +4.75V to +5.25V, RBIAS = 5.9Ω, LBIAS = 680nH, TA = -40°C to +85°C, unless otherwise indicated. Typical values measured at VCC = +5.0V, TA = +25°C.) (Notes 1, 2) PARAMETERS CONDITIONS MIN TYP MAX UNITS SUPPLY Supply Voltage 4.75 Supply Current 85 OPERATIONAL AMPLIFIER Common-Mode Input Range 0.5 Maximum Output Voltage IO = 20mA Minimum Output Voltage IO = 20mA 5.25 V 95 mA 3.0 VCC - 0.5 V V 0.5 V AC ELECTRICAL CHARACTERISTICS (MAX3524 EV kit as shown in Figure 1, VCC = +4.75V to +5.25V, PRFIN = -20dBm, ZS = 75Ω, RBIAS = 5.9Ω, LBIAS = 680nH, fIN = 44MHz, ZL = 50Ω || 2pF, TA = +25°C. Typical values are at VCC = +5V, unless otherwise indicated.) (Notes 2, 3) PARAMETERS CONDITIONS Operating Frequency Range Power Gain (Note 4) MIN TYP 44 TA = +25°C 8.0 TA = -40°C to +85°C 7.6 9.8 MAX UNITS 880 MHz 11 11.5 Voltage Gain (Note 5) RL = 3kΩ 15 Noise Figure (Note 3) fRFIN = 300MHz 4.2 dB dB 4.9 dB IIP3 (Notes 3, 6) 12 14 dBm IIP2 (Notes 3, 6) 40 42 dBm 40 60 dB Output-to-Input Isolation fRFIN = 300MHz Note 1: Parameters are production tested at TA = +25°C and TA = +85°C. Limits are guaranteed by design and characterization for TA = -40°C to +25°C. Note 2: For optimum linearity, the DC resistance of LBIAS in series with RBIAS must be approximately 7.3Ω. Note 3: Guaranteed by design and characterization. Note 4: Gain is guaranteed over the operating frequency range, by design and characterization. Insertion loss of balun is subtracted. Production tested at 44MHz and 880MHz. Note 5: Corresponding voltage gain at RL = 3kΩ, calculated as in Figure 2. Note 6: Frequencies and input power levels: 275MHz, 325MHz, and -20dBm per tone. 2 _______________________________________________________________________________________ Low-Noise, High-Linearity Broadband Amplifier (MAX3524 EV kit as shown in Figure 1, VCC = +5V, PRFIN = -20dBm, ZL = 50Ω || 2pF, RBIAS = 5.9Ω, LBIAS = 680nH, insertion loss of balun subtracted, TA = +25°C.) POWER GAIN vs. FREQUENCY Zs = 50Ω CL = 1.5pF TA = -45°C TA = +25°C 10 GAIN (dB) 87 86 TA = +25°C TA = +85°C 9 TA = +85°C 7 40 140 240 340 440 540 640 740 840 940 40 140 240 340 440 540 640 740 840 940 VCC (V) FREQUENCY (MHz) FREQUENCY (MHz) 10 9 GAIN (dB) VCC = 4.75, 5.00, 5.25 8 7 7 6 VCC = 4.75, 5.00, 5.25 9 8 MAX3524 toc06 TA = +85°C 5 4 TA = +25°C 3 TA = -40°C 2 1 0 6 40 140 240 340 440 540 640 740 840 940 40 140 240 340 440 540 640 740 840 940 40 140 240 340 440 540 640 740 840 940 FREQUENCY (MHz) FREQUENCY (MHz) FREQUENCY (MHz) IIP3 vs. FREQUENCY IIP2 vs. FREQUENCY 1dB COMPRESSED OUTPUT POWER vs. FREQUENCY TA = -40°C Zs = 75Ω 55 12 POUT (dBm) IIP2 (dBm) 50 TA = +85°C 14 TA = +85°C 16 TA = +25°C 16 TA = +25°C 45 12 40 10 35 TA = -40°C MAX3524toc09 18 60 MAX3524 toc07 Zs = 75Ω MAX3524 toc08 GAIN (dB) TA = +25°C Zs = 75Ω CL = 1.5pF NOISE FIGURE (dB) 11 6 MAX3524 toc05 MAX3524 toc04 TA = +25°C Zs = 50Ω CL = 1.5pF NOISE FIGURE vs. FREQUENCY POWER GAIN vs. FREQUENCY 12 10 IIP3 (dBm) 6 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5 POWER GAIN vs. FREQUENCY 14 TA = +85°C 7 6 82 20 TA = +25°C 10 8 83 11 TA = -40°C 11 9 8 84 12 Zs = 75Ω CL = 1.5pF 12 TA = -40°C 85 13 GAIN (dB) 88 11 POWER GAIN vs. FREQUENCY 14 MAX3524 toc03 MAX3524toc01 89 ICC (mA) 12 MAX3524 toc02 CURRENT vs. VOLTAGE 90 VCC = 5.25V 10 8 VCC = 4.75V VCC = 5.00V 8 6 4 30 50 150 250 350 450 550 650 750 850 950 FREQUENCY (MHz) 100 200 300 400 500 600 700 800 900 1000 FREQUENCY (MHz) 40 140 240 340 440 540 640 740 840 940 FREQUENCY (MHz) _______________________________________________________________________________________ 3 MAX3524 Typical Operating Characteristics Typical Operating Characteristics (continued) (MAX3524 EV kit as shown in Figure 1, VCC = +5V, PRFIN = -20dBm, ZL = 50Ω || 2pF, RBIAS = 5.9Ω, LBIAS = 680nH, insertion loss of balun subtracted, TA = +25°C.) ISOLATION vs. FREQUENCY PSRR vs. FREQUENCY MAX3524toc11 -45 -45 -50 -50 -55 -55 PSRR (dB) ISOLATION (dB) -40 MAX3524toc10 -40 -60 -60 -65 -65 -70 -70 -75 -75 -80 -80 40 440 240 640 840 20 ZIN = R II C OP AMP CLOSED-LOOP VOLTAGE GAIN OF 2 vs. FREQUENCY 2.5 6 350 5 CAPACITANCE 150 1.5 4 VGAIN (dB) 2.0 250 CAPACITANCE (pF) RESISTANCE 200 220 MAX3524 toc13 MAX3524 toc12 300 170 FREQUENCY (MHz) RESISTANCE AND CAPACITANCE vs. FREQUENCY 400 120 70 FREQUENCY (MHz) RESISTANCE (Ω) MAX3524 Low-Noise, High-Linearity Broadband Amplifier 3 2 100 1 50 1 0 40 240 440 640 0 840 0 FREQUENCY (MHz) 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 FREQUENCY (MHz) Pin Description 4 PIN NAME FUNCTION 1, 9 VCC Supply Voltage Input. Connect both pins together. Bypass with a 10µF and 47pF capacitor to GND. 2 RFIN RF Input of LNA. Requires DC blocking capacitor. 3 RFGND Bypass to GND through 10nF capacitor. 4 OPOUT Operational Amplifier Output 5 OPIN- Inverting Input of Operational Amplifier 6 BIAS LNA Bias Setting Pin. For nominal bias, connect 5.9Ω resistor in series with 680nH to GND (total DC resistance = resistance of RBIAS + DC resistance of the inductor = 7.3Ω). The value of the resistor is adjusted to alter the current and therefore linearity of the LNA. 7 OPIN+ Noninverting Input of Operational Amplifier 8 RFOUT- Inverting Output of LNA 10 RFOUT+ Slug GND Noninverting Output of LNA Ground _______________________________________________________________________________________ Low-Noise, High-Linearity Broadband Amplifier The MAX3524 is a broadband amplifier with a singleended input and differential outputs, including an operational amplifier that can be used to control an external attenuator circuit. Figure 1 is the MAX3524 EV kit schematic. Low-Noise Amplifier The low-noise amplifier operates from 44MHz to 880MHz and is designed specifically for cable TV and cable modem applications. The LNA provides 15dB of insertion voltage gain (see Figure 2) when driving a 3kΩ load. At 300MHz, the noise figure is 4.2dB, IIP2 and IIP3 are 42dBm and 14dBm, respectively. Operational Amplifier The operational amplifier is suitable for interfacing to a PIN attenuator circuit which is typically employed at the input of the LNA. The common-mode input range is 0.5V to 3V and the output voltage swing is 0.5V to VCC 0.5V while sinking or sourcing 20mA. Input bias current and input offset voltage are 1µA and 1mV, respectively. The open-loop voltage gain is greater than 10,000. The gain bandwidth product is greater than 1MHz for a closed-loop voltage gain of one. VCC C15 0.1µF C1 47pF R1 13.3Ω C10 RF INPUT 0.1µF VCC R2 C11 0.1µF RF OUTPUT C14 47pF C15 0.1µF VCC2 C2 2pF RF OUT+ R4 50kΩ C12 0.1µF VCC RFIN VCC TO ATTENUATOR RF OUT- RFGND R3 50kΩ R9 100Ω OPIN+ 0.1µF OP OUT R10 3kΩ BIAS D1 OP IN R8 3kΩ R7 10kΩ D2 LBIAS VCC RBIAS 5.81Ω D1, D2 SMALL-SIGNAL SCHOTTKY DIODES, TYPICALLY CMDSH-3 Figure 1. MAX3524 EV Kit Schematic VCC (PIN9) 75Ω RFIN AV = (VRFOUT +) - (VRFOUT-) = 5.7 VIN AV(dB) = 20log10 AV = 15dB V1 ZS 330Ω 2VIN 1.8pF 30Ω 30Ω RFOUT+ 0.06V1 RFOUT- Figure 2. LNA Equivalent Circuit and Open-Circuit Voltage Gain Calculation _______________________________________________________________________________________ 5 MAX3524 Detailed Description MAX3524 Low-Noise, High-Linearity Broadband Amplifier Table 1. Shunt-Resistor Noise-Figure Values RSHUNT(Ω) S11(LNA) (dB) NOISE FIGURE (dB) 450 -6 5 to 5.5 250 -8 5.5 to 6 125 -10 6 to 6.5 Applications Information Bias Current The resistor, RBIAS, connected between BIAS and GND controls the LNA current. To make the current insensitive to temperature fluctuations, select a 1%, low temperature coefficient resistor for R BIAS . The current drawn by the LNA is calculated using the following formula: IBIAS ≈ 0.58V / (RBIAS + DC resistance of LBIAS) It is important to include the inductor resistance in the above equation as it is typically 1Ω to 2Ω. The MAX3524 EV kit uses a nominal inductor with DC resistance of 1.4Ω. Higher values of RBIAS may be used to reduce supply current predominantly at the expense of linearity. Circuit board layout and source impedance may require the value of IBIAS to be optimized for best linearity. RF Input Power Control Using the Operational Amplifier In a cable system, the power level at the LNA input is typically restricted to a maximum value to maintain linearity. This is accomplished by connecting a variable attenuator at the input of the LNA and varying the attenuation with the operational amplifier output. The operational amplifier receives a DC control input that is proportional to LNA output power. See Typical Application Circuit. Layout Issues A properly designed PC board is essential to any RF/microwave circuit. Use short interconnect and controlled impedance lines on all high-frequency inputs and outputs. Use low inductance connections to ground on all GND nodes and place decoupling capacitors close to all VCC connections. The EP is the ground for the MAX3524 and must be soldered to ground for proper operation. Pin Configuration TOP VIEW VCC 1 Input and Output RFIN The LNA input is single-ended. The RF input signal is coupled to RFIN through a DC blocking capacitor. The LNA outputs drive a differential load, such as a mixer, through DC blocking capacitors. The equivalent input LNA impedance is 330Ω resistive in parallel with 1.8pf, as shown in Figure 2. The approximate equivalent differential output impedance of the LNA is 60Ω. To achieve S11 less than -6dB, an insertion loss of greater than 1dB must exist between the cable input and MAX3524. This loss typically comes from a diplexer and PIN attenuator in a cable modem application. A shunt resistor may be added at the input of the LNA to improve the return loss (S11). Typically the return loss of the system is 2dB better, as explained above. The S11 and noise-figure values for different shunt resistors are given in Table 1. RFGND 3 OPOUT OPIN- 6 10 RFOUT+ 2 9 VCC 8 REFOUT- 4 7 OPIN+ 5 6 BIAS MAX3524 µMAX Chip Information TRANSISTOR COUNT: 550 _______________________________________________________________________________________ Low-Noise, High-Linearity Broadband Amplifier 10LUMAX.EPS e 4X S 10 10 INCHES H fl 0.50–0.1 0.6–0.1 1 1 0.6–0.1 BOTTOM VIEW TOP VIEW D2 MILLIMETERS MAX DIM MIN 0.043 A 0.006 A1 0.002 A2 0.030 0.037 0.120 D1 0.116 0.118 D2 0.114 0.120 E1 0.116 0.118 E2 0.114 0.199 H 0.187 L 0.0157 0.0275 L1 0.037 REF 0.0106 b 0.007 e 0.0197 BSC c 0.0035 0.0078 0.0196 REF S α 0¡ 6¡ MAX MIN 1.10 0.15 0.05 0.75 0.95 3.05 2.95 3.00 2.89 2.95 3.05 2.89 3.00 4.75 5.05 0.40 0.70 0.940 REF 0.177 0.270 0.500 BSC 0.090 0.200 0.498 REF 0¡ 6¡ E2 GAGE PLANE A2 c A b A1 α E1 L D1 L1 FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, 10L uMAX/uSOP APPROVAL DOCUMENT CONTROL NO. 21-0061 REV. I 1 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 7 © 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc. MAX3524 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)