19-2799; Rev 0; 4/03 Digitally Controlled, Variable-Gain, Differential ADC Driver/Amplifier Applications Cellular Base Stations PHS/PAS Infrastructure Features ♦ 30MHz to 300MHz Frequency Range ♦ Single-Ended-to-Differential Conversion ♦ -3dB to +20dB Variable Gain ♦ 40dBm Output IP3 (at All Gain States and 70MHz) ♦ 2nd Harmonic -76dBc ♦ 3rd Harmonic -69dBc ♦ Noise Figure: 5.8dB at Maximum Gain ♦ Digitally Controlled Gain with 1dB Resolution and ±0.2dB Accuracy ♦ Adjustable Bias Current Ordering Information PART MAX2055EUP-T TEMP RANGE PIN-PACKAGE -40°C to +85°C 20 TSSOP-EP* *EP = Exposed paddle. Receiver Gain Control Broadband Systems Pin Configuration/ Functional Diagram Automatic Test Equipment Terrestrial Links High-Performance ADC Drivers TOP VIEW 20 GND VCC 1 19 ATTNOUT RF_IN 2 GND 3 MAX2055 17 ISET B4 4 B3 5 B2 6 B1 7 18 GND ATTENUATION LOGIC CONTROL 16 CC 15 AMPIN 14 LE B0 8 13 CBP VCC 9 12 IBIAS 11 RF_OUT+ RF_OUT- 10 TSSOP ________________________________________________________________ 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 MAX2055 General Description The MAX2055 high-performance, digitally controlled, variable-gain, differential analog-to-digital converter (ADC) driver/amplifier (DVGA) is designed for use from 30MHz to 300MHz in base station receivers. The device integrates a digitally controlled attenuator and a high-linearity single-ended-to-differential output amplifier, which can either eliminate an external transformer, or can improve the even-order distortion performance of a transformer-coupled circuit, thus relaxing the requirements of the anti-alias filter preceding an ADC. Targeted for ADC driver applications to adjust gain either dynamically or as a one-time channel gain setting, the MAX2055 is ideal for applications requiring high performance. The attenuator provides 23dB of attenuation range with ±0.2dB accuracy. The MAX2055 is available in a thermally enhanced 20pin TSSOP-EP package and operates over the -40°C to +85°C temperature range. MAX2055 Digitally Controlled, Variable-Gain, Differential ADC Driver/Amplifier ABSOLUTE MAXIMUM RATINGS All Pins to GND. .....................................-0.3V to +(VCC + 0.25V) Input Signal (RF_IN)............................…………………….20dBm Output Power (RF_OUT) ...................................................24dBm Continuous Power Dissipation (TA = +70°C) 20-Pin TSSOP (derate 21.7mW/°C above +70°C) ...........2.1W Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +165°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. DC ELECTRICAL CHARACTERISTICS (Circuit of Figure 1; VCC = +4.75V to +5.25V, GND = 0V. No input signals applied, and input and output ports are terminated with 50Ω. R1 = 1.13kΩ, TA = -40°C to +85°C. Typical values are at VCC = +5V and TA = +25°C, unless otherwise noted.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 4.75 5.0 5.25 V 290 SUPPLY Supply Voltage VCC Supply Current ICC 240 ISET Current ISET 1.1 mA mA 5 Bits CONTROL INPUTS Control Bits Parallel Input Logic High 2 V Input Logic Low Input Leakage Current -1.2 0.6 V +1.2 µA AC ELECTRICAL CHARACTERISTICS (Circuit of Figure 1; VCC = +4.75V to +5.25V, GND = 0V, max gain (B0 = B1 = B2 = B3 = B4 = 0), R1 = 1.13kΩ, POUT = 5dBm, fIN = 70MHz, 50Ω system impedance. Typical values are at VCC = +5V and TA = +25°C, unless otherwise noted.) (Notes 1, 2) PARAMETER SYMBOL Frequency Range fR Gain G CONDITIONS MIN TYP 30 19.9 MAX UNITS 300 MHz dB Amplitude Unbalance (Note 3) 0.06 dB Phase Unbalance (Note 3) 0.7 Degrees 29 dB Minimum Reverse Isolation Noise Figure NF 5.8 dB Output 1dB Compression Point P1dB 25.7 dBm 2nd-Order Output Intercept Point OIP2 f1 + f2, f1 = 70MHz, f2 = 71MHz, 5dBm/tone at RF_OUT 75 dBm 3rd-Order Output Intercept Point OIP3 All gain conditions, 5dBm/tone at RF_OUT 40 dBm 2nd Harmonic 2fIN -76 dBc 3rd Harmonic 3fIN -69 dBc RF Gain-Control Range 23 dB Gain-Control Resolution 1 dB ±0.2 dB +0.05/ -0.2 dB ±0.3 dB Attenuation Absolute Accuracy Compared to the ideal expected attenuation Attenuation Relative Accuracy Between adjacent states Gain Drift Over Temperature TA = -40°C to +85°C 2 _______________________________________________________________________________________ Digitally Controlled, Variable-Gain, Differential ADC Driver/Amplifier (Circuit of Figure 1; VCC = +4.75V to +5.25V, GND = 0V, max gain (B0 = B1 = B2 = B3 = B4 = 0), R1 = 1.13kΩ, POUT = 5dBm, fIN = 70MHz, 50Ω system impedance. Typical values are at VCC = +5V and TA = +25°C, unless otherwise noted.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Gain Flatness Over 50MHz Bandwidth Peak-to-peak for all settings Attenuator Switching Time 50% control to 90% RF 40 ns Input Return Loss fR = 30MHz to 300MHz, all gain conditions 15 dB fR = 30MHz to 250MHz, all gain conditions 15 fR = 250MHz to 300MHz, all gain conditions 12 Output Return Loss 0.5 dB dB Note 1: Guaranteed by design and characterization. Note 2: All limits reflect losses of external components. Output measurements are taken at RF_OUT using the application circuit shown in Figure 1. Note 3: The amplitude and phase unbalance are tested with 50Ω resistors connected from OUT+/OUT- to GND. Typical Operating Characteristics (Circuit of Figure 1, VCC = 5.0V, R1 = 1.13kΩ, max gain (B0 = B1 = B2 = B3 = B4 = 0), POUT = 5dBm, TA = +25°C, unless otherwise noted.) INPUT RETURN LOSS vs. RF FREQUENCY (ALL STATES) VCC = 5.0V 240 230 VCC = 4.75V 220 210 -15 10 35 60 15 20 25 30 25 30 35 30 60 90 120 150 180 210 240 270 300 30 MAX2055 toc04 24 22 TA = -40°C GAIN vs. RF FREQUENCY 24 22 18 TA = +25°C 16 TA = +85°C 18 VCC = 5.25V 14 14 -5 12 12 10 90 120 150 180 210 240 270 300 FREQUENCY (MHz) VCC = 5.0V 16 0 -10 VCC = 4.75V 20 GAIN (dB) GAIN (dB) 5 90 120 150 180 210 240 270 300 FREQUENCY (MHz) GAIN vs. RF FREQUENCY 10 60 60 FREQUENCY (MHz) 20 30 MAX2055 toc03 20 40 85 15 GAIN (dB) 15 35 GAIN vs. RF FREQUENCY (ALL STATES) 20 10 40 TEMPERATURE (°C) 25 5 MAX2055 toc05 -40 10 0 MAX2055 toc06 VCC = 5.25V 250 MAX2055 toc02 5 INPUT RETURN LOSS (dB) 260 SUPPLY CURRENT (mA) 0 MAX2055 toc01 270 OUTPUT RETURN LOSS vs. RF FREQUENCY (ALL STATES) OUTPUT RETURN LOSS (dB) SUPPLY CURRENT vs. TEMPERATURE 10 30 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) 30 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) _______________________________________________________________________________________ 3 MAX2055 AC ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (Circuit of Figure 1, VCC = 5.0V, R1 = 1.13kΩ, max gain (B0 = B1 = B2 = B3 = B4 = 0), POUT = 5dBm, TA = +25°C, unless otherwise noted.) 0.8 0.2 0 -0.2 -0.4 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.6 -0.8 -0.8 -1.0 90 120 150 180 210 240 270 300 30 60 FREQUENCY (MHz) OUTPUT P-1dB vs. FREQUENCY 27 MAX2055 toc10 26 OUTPUT P-1dB (dBm) 7.5 NOISE FIGURE (dB) 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) TA = +85°C 6.5 6.0 TA = +25°C TA = -40°C OUTPUT P-1dB vs. FREQUENCY TA = +85°C 25 24 TA = -40°C 27 26 OUTPUT P-1dB (dBm) NOISE FIGURE vs. FREQUENCY 5.5 30 FREQUENCY (MHz) 8.0 7.0 28 20 90 120 150 180 210 240 270 300 MAX2055 toc11 60 32 24 -1.0 30 36 TA = +25°C 23 MAX2055 toc12 0.4 REVERSE ISOLATION (dB) RELATIVE ACCURACY (dB) 0.6 REVERSE ISOLATION vs. RF FREQUENCY 40 MAX2055 toc08 0.8 ABSOLUTE ACCURACY (dB) 1.0 MAX2055 toc07 1.0 ATTENUATION RELATIVE ACCURACY (ALL STATES) MAX2055 toc09 ATTENUATION ABSOLUTE ACCURACY (ALL STATES) VCC = +5.25V 25 24 VCC = +5V VCC = +4.75V 23 5.0 22 4.0 22 21 60 90 120 150 180 210 240 270 300 21 30 60 FREQUENCY (MHz) 30 OUTPUT IP3 vs. FREQUENCY 42 INPUT IP3 vs. ATTENUATION STATE 55 VCC = +5.25V 45 TA = +25°C 38 VCC = +5V 36 VCC = +4.75V TA = -40°C 34 IIP3 (dBm) 38 34 32 PRF1 = PRF2 = 5dBm AT OUTPUT, ∆f = 1MHz 30 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) 40 35 30 25 32 PRF1 = PRF2 = 5dBm AT OUTPUT, ∆f = 1MHz 30 30 PRF1 = PRF2 = 5dBm AT OUTPUT, ∆f = 1MHz, fIN = 70MHz 50 40 OIP3 (dBm) 40 TA = +85°C 90 120 150 180 210 240 270 300 FREQUENCY (MHz) OUTPUT IP3 vs. FREQUENCY 44 MAX2055 toc13 42 36 60 FREQUENCY (MHz) 44 4 90 120 150 180 210 240 270 300 MAX2055 toc14 30 MAX2055 toc15 4.5 OIP3 (dBm) MAX2055 Digitally Controlled, Variable-Gain, Differential ADC Driver/Amplifier 20 15 30 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) 0 4 8 12 16 ATTENUATION STATE _______________________________________________________________________________________ 20 24 Digitally Controlled, Variable-Gain, Differential ADC Driver/Amplifier 2ND HARMONIC vs. FREQUENCY -60 MAX2055 toc17 MAX2055 toc16 TA = -40°C -60 3RD HARMONIC vs. FREQUENCY -55 -60 TA = +85°C TA = -40°C -65 MAX2055 toc18 3RD HARMONIC vs. FREQUENCY -55 TA = +25°C TA = +85°C -75 -80 -65 -70 VCC = +5V VCC = +4.75V -75 90 120 150 180 210 240 270 300 30 60 FREQUENCY (MHz) OUTPUT IP2 vs. FREQUENCY (f1 + f2) VCC = +4.75V 80 VCC = +5.0 VCC = +4.75V 75 OIP2 (dBm) OIP2 (dBm) -75 VCC = +5V OUTPUT IP2 vs. FREQUENCY (f1 + f2) 85 75 -70 70 65 TA = -40°C 60 -85 55 -90 90 120 150 180 210 240 270 300 60 90 120 150 180 210 240 270 300 PRF1 = PRF2 = 5dBm AT OUTPUT, ∆f = 1MHz 30 FREQUENCY (MHz) 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) OUTPUT-PORT AMPLITUDE UNBALANCE vs. FREQUENCY OUTPUT-PORT PHASE UNBALANCE vs. FREQUENCY 0.15 0.10 0.05 MAX2055 toc23 3.0 PHASE UNBALANCE (DEGREES) 0.20 VCC = +5.25V 50 30 FREQUENCY (MHz) 0.25 65 55 PRF1 = PRF2 = 5dBm AT OUTPUT, ∆f = 1MHz MAX2055 toc22 60 70 60 TA = +85°C 50 30 AMPLITUDE UNBALANCE (dB) HARMONIC (dBc) VCC = +5.25V -80 TA = +25°C 80 90 120 150 180 210 240 270 300 FREQUENCY (MHz) 85 MAX2055 toc19 -65 60 FREQUENCY (MHz) 2ND HARMONIC vs. FREQUENCY -60 TA = +25°C 30 90 120 150 180 210 240 270 300 MAX2055 toc20 60 -80 -90 -85 30 -75 -85 -80 -85 -70 MAX2055 toc21 -70 HARMONIC (dBc) HARMONIC (dBc) HARMONIC (dBc) VCC = +5.25V -65 2.5 2.0 1.5 1.0 0.5 0 0 30 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) 30 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) _______________________________________________________________________________________ 5 MAX2055 Typical Operating Characteristics (continued) (Circuit of Figure 1, VCC = 5.0V, R1 = 1.13kΩ, max gain (B0 = B1 = B2 = B3 = B4 = 0), POUT = 5dBm, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (Circuit of Figure 2, VCC = 5.0V, R1 = 909Ω, max gain, (B0 = B1 = B2 = B3 = B4 = 0), POUT = 5dBm, TA = +25°C, unless otherwise noted.) INPUT RETURN LOSS vs. RF FREQUENCY (ALL STATES) VCC = 5.0V 240 230 VCC = 4.75V 30 40 -15 10 35 60 60 GAIN vs. RF FREQUENCY (ALL STATES) 90 120 150 180 210 240 270 300 30 60 22 GAIN vs. RF FREQUENCY 24 22 10 5 VCC = 4.75V 20 GAIN (dB) 20 GAIN (dB) 15 TA = -40°C 90 120 150 180 210 240 270 300 FREQUENCY (MHz) GAIN vs. RF FREQUENCY 24 MAX2055 toc27 20 40 FREQUENCY (MHz) TEMPERATURE (°C) 25 30 60 30 85 MAX2055 toc28 -40 20 50 60 210 GAIN (dB) 10 50 220 MAX2055 toc26 MAX2055 toc25 20 0 18 TA = +25°C 16 18 VCC = 5.25V 16 VCC = 5.0V TA = +85°C 0 14 14 -5 12 12 10 30 60 90 120 150 180 210 240 270 300 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) FREQUENCY (MHz) ATTENUATION ABSOLUTE ACCURACY (ALL STATES) ATTENUATION RELATIVE ACCURACY (ALL STATES) 0.8 RELATIVE ACCURACY (dB) 0.6 0.4 0.2 0 -0.2 -0.4 0.6 0.2 0 -0.2 -0.4 -0.6 -0.8 -0.8 -1.0 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) 40 36 32 28 24 -1.0 30 90 120 150 180 210 240 270 300 REVERSE ISOLATION vs. RF FREQUENCY 0.4 -0.6 60 FREQUENCY (MHz) REVERSE ISOLATION (dB) 0.8 30 MAX2055 toc31 1.0 MAX2055 toc30 1.0 6 10 30 MAX2055 toc32 -10 MAX2055 toc29 VCC = 5.25V 250 10 INPUT RETURN LOSS (dB) 260 SUPPLY CURRENT (mA) 0 MAX2055 toc24 270 OUTPUT RETURN LOSS vs. FREQUENCY (ALL STATES) OUTPUT RETURN LOSS (dB) SUPPLY CURRENT vs. TEMPERATURE ABSOLUTE ACCURACY (dB) MAX2055 Digitally Controlled, Variable-Gain, Differential ADC Driver/Amplifier 30 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) 20 30 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) _______________________________________________________________________________________ Digitally Controlled, Variable-Gain, Differential ADC Driver/Amplifier 6.5 6.0 5.5 TA = +25°C TA = +85°C 25 24 TA = +25°C TA = -40°C 26 23 MAX2055 toc35 26 OUTPUT P-1dB (dBm) NOISE FIGURE (dB) 7.0 OUTPUT P-1dB vs. FREQUENCY 27 MAX2055 toc34 MAX2055 toc33 TA = +85°C 7.5 OUTPUT P-1dB vs. FREQUENCY 27 OUTPUT P-1dB (dBm) NOISE FIGURE vs. FREQUENCY 8.0 VCC = +5.25V 25 24 VCC = +5V VCC = +4.75V 23 5.0 22 4.0 22 21 90 120 150 180 210 240 270 300 21 30 60 FREQUENCY (MHz) OUTPUT IP3 vs. FREQUENCY 60 90 120 150 180 210 240 270 300 TA = +25°C FREQUENCY (MHz) INPUT IP3 vs. ATTENUATION STATE OUTPUT IP3 vs. FREQUENCY 44 MAX2055 toc36 42 42 VCC = +5.25V TA = +85°C 36 55 PRF1 = PRF2 = 5dBm AT OUTPUT, ∆f = 1MHz, fIN = 70MHz 50 45 40 OIP3 (dBm) 40 38 30 FREQUENCY (MHz) 44 OIP3 (dBm) 90 120 150 180 210 240 270 300 VCC = +4.75V 38 IIP3 (dBm) 60 MAX2055 toc37 30 MAX2055 toc38 TA = -40°C 4.5 VCC = +5V 36 40 35 30 TA = -40°C 32 34 25 32 PRF1 = PRF2 = 5dBm AT OUTPUT, ∆f = 1MHz 30 PRF1 = PRF2 = 5dBm AT OUTPUT, ∆f = 1MHz 20 15 30 30 60 90 120 150 180 210 240 270 300 30 60 FREQUENCY (MHz) 3RD HARMONIC vs. FREQUENCY -75 -65 VCC = +5.25V -70 20 -55 VCC = +5V -75 HARMONIC (dBc) -70 16 24 2ND HARMONIC vs. FREQUENCY MAX2055 toc40 -60 HARMONIC (dBc) HARMONIC (dBc) TA = -40°C 12 -50 -60 -65 8 ATTENUATION STATE -55 MAX2055 toc39 -60 4 FREQUENCY (MHz) 3RD HARMONIC vs. FREQUENCY -55 0 90 120 150 180 210 240 270 300 MAX2055 toc41 34 TA = -40°C TA = +25°C -65 -70 -75 -80 TA = +85°C -80 TA = +25°C -80 VCC = +4.75V -85 -90 -85 30 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) TA = +85°C -85 30 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) 30 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) _______________________________________________________________________________________ 7 MAX2055 Typical Operating Characteristics (continued) (Circuit of Figure 2, VCC = 5.0V, R1 = 909Ω, max gain, (B0 = B1 = B2 = B3 = B4 = 0), POUT = 5dBm, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (Circuit of Figure 2, VCC = 5.0V, R1 = 909Ω, max gain, (B0 = B1 = B2 = B3 = B4 = 0), POUT = 5dBm, TA = +25°C, unless otherwise noted.) OUTPUT IP2 vs. FREQUENCY (f1 + f2) -55 TA = +85°C 80 -60 OUTPUT IP2 vs. FREQUENCY (f1 + f2) 75 75 -70 -75 VCC = +5V 70 65 TA = +25°C VCC = +4.75V 60 -90 60 90 120 150 180 210 240 270 300 60 90 120 150 180 210 240 270 300 30 FREQUENCY (MHz) 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) OUTPUT-PORT PHASE UNBALANCE vs. FREQUENCY 0.15 0.10 0.05 MAX2055 toc46 3.0 PHASE UNBALANCE (DEGREES) MAX2055 toc45 AMPLITUDE UNBALANCE (dB) PRF1 = PRF2 = 5dBm AT OUTPUT, ∆f = 1MHz 50 30 OUTPUT-PORT AMPLITUDE UNBALANCE vs. FREQUENCY 0.20 VCC = +5.25V 55 PRF1 = PRF2 = 5dBm AT OUTPUT, ∆f = 1MHz FREQUENCY (MHz) 0.25 65 60 50 30 VCC = +4.75V TA = -40°C 55 -85 VCC = +5.0V 70 OIP2 (dBm) OIP2 (dBm) VCC = +5.25V -65 -80 2.5 2.0 1.5 1.0 0.5 0 0 30 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) 8 80 MAX2055 toc43 MAX2055 toc42 85 MAX2055 toc44 2ND HARMONIC vs. FREQUENCY -50 HARMONIC (dBc) MAX2055 Digitally Controlled, Variable-Gain, Differential ADC Driver/Amplifier 30 60 90 120 150 180 210 240 270 300 FREQUENCY (MHz) _______________________________________________________________________________________ Digitally Controlled, Variable-Gain, Differential ADC Driver/Amplifier PIN NAME FUNCTION 1, 9 VCC 2 RF_IN Signal Input. Internally matched to 50Ω over the operating frequency. See the typical application circuit for recommended component values. 3, 18, 20, EP GND Ground. Use low-inductance layout techniques on the PC board. Solder the exposed paddle to the board ground plane. 4–8 B4–B0 10 RF_OUT- Inverted Differential Signal Output. Requires an external pullup choke inductor (120mA typical current) to VCC along with a DC-blocking capacitor; see Figures 1 and 2. 11 RF_OUT+ Noninverted Differential Signal Output. Requires an external pullup choke inductor (120mA typical current) to VCC along with a DC-blocking capacitor; see Figures 1 and 2. 12 IBIAS Amplifier Bias Input. See Figures 1 and 2 for detailed connection. 13 CBP Bypass Capacitor. See Figures 1 and 2 for detailed connection. 14 LE 15 AMPIN 16 CC Compensation Capacitor. Requires connection to AMPIN (pin 15) for stability. 17 ISET Connect R1 from ISET to GND (see Table 1 or Table 2 for values). 19 ATTNOUT Power Supply. Bypass to GND with capacitors as close to the pin as possible as shown in the typical application circuits (Figures 1 and 2). Attenuation Control Bits. Digital input for attenuation control. See Table 3 for attenuation setting. Amplifier DC Ground. Requires choke inductor that can handle supply current. DC resistance of inductor should be less than 0.2Ω. Amplifier Input. Requires DC-coupling to allow biasing. Attenuator Output. Requires external DC-blocking capacitor. Table 1. Suggested Components of Circuit of Figure 1 COMPONENT Table 2. Suggested Components of Circuit of Figure 2 VALUE SIZE 1nF 0603 C1, C3, C4, C5, C7–C10, C12 C2, C11 100pF 0603 L1, L3 330nH L2 VALUE SIZE 1nF 0603 C2, C11 100pF 0603 0603 L1, L2, L3 330nH 0603 100nH 0603 L4, L5 680nH 1008 L4, L5 680nH 1008 R1 909Ω 0603 R1 1.13kΩ 0603 R7 10Ω 0603 R7 10Ω 0603 T2 1:1 — T1, T2 1:1 — C1, C3–C6, C8, C9, C10, C12 COMPONENT _______________________________________________________________________________________ 9 MAX2055 Pin Description MAX2055 Digitally Controlled, Variable-Gain, Differential ADC Driver/Amplifier VCC C3 C2 C4 1 20 GND ATTNOUT 19 VCC 2 RF_IN RF_IN 3 C1 5 B3 6 B2 7 B1 ATTENUATION LOGIC CONTROL C12 C5 LE 14 1 L2 L1 CBP 13 9 V CC VCC R1 16 CC AMPIN 15 8 B0 R7 T1 18 GND ISET 17 GND 4 B4 CONTROL INPUTS C6 MAX2055 IBIAS 12 11 C11 L3 RF_OUT+ 10 RF_OUTVCC L5 L4 C10 C8 C9 1 T2 RF_OUT Figure 1. Typical Application Circuit Detailed Description The MAX2055 is a high-dynamic-range, digitally controlled, variable-gain differential ADC driver/amplifier (DVGA) for use in applications from 30MHz to 300MHz. The amplifier is designed for 50Ω single-ended input and 50Ω differential output systems. The MAX2055 integrates a digital attenuator with a 23dB selectable attenuation range and a high-linearity, single-ended-to-differential output amplifier. The attenuator is digitally controlled through five logic lines: B0–B4. The on-chip attenuator provides up to 23dB of attenuation with ±0.2dB accuracy. The single-ended input to differential output amplifier utilizes negative 10 feedback to achieve high gain and linearity over a wide bandwidth. Applications Information Digitally Controlled Attenuator The digital attenuator is controlled through five logic lines: B0, B1, B2, B3, and B4. Table 3 lists the attenuation settings. The input and output of this attenuator require external DC blocking capacitors. The attenuator’s insertion loss is approximately 2dB, when the control bits are set to 0dB (B0 = B1 = B2 = B3 = B4 = 0). Single-Ended-to-Differential Amplifier The MAX2055 integrates a single-ended-to-differential amplifier with a nominal gain of 22dB in a negative ______________________________________________________________________________________ Digitally Controlled, Variable-Gain, Differential ADC Driver/Amplifier MAX2055 VCC C3 C2 1 V CC GND 20 ATTNOUT 19 2 RF_IN RF_IN 3 C1 GND 18 GND 5 B3 CONTROL INPUTS 6 B2 7 B1 VCC AMPIN 15 LE 14 L2 CBP 13 9 V CC C12 MAX2055 IBIAS L1 12 C7 11 C11 C4 C5 CC 16 ATTENUATION LOGIC CONTROL 8 B0 R7 R1 ISET 17 4 B4 10 RF_OUT- L3 RF_OUT+ VCC L5 L4 C10 C8 C9 1 T2 RF_OUT Figure 2. Low-Cost Application Circuit feedback topology. This amplifier is optimized for a frequency range of operation from 30MHz to 300MHz with a high-output third-order intercept point (OIP3). The bias current is chosen to optimize the IP3 of the amplifier. When R 1 is 1.13kΩ (909Ω if using the circuit of Figure 2), the current consumption is 240mA while exhibiting a 40dBm typical output IP3 at 70MHz. The common-mode inductor, L2, provides a high commonmode rejection with excellent amplitude and phase balance at the output. L2 must handle the supply current and have DC resistance less than 0.2Ω. Choke Inductor The single-ended amplifier input and differential output ports require external choke inductors. At the input, connect a 330nH bias inductor from AMPIN (pin 15) to IBIAS (pin 12). Connect 680nH choke inductors from RF_OUT+ (pin 11) and RF_OUT- (pin 10) to VCC. These connections provide bias current to the amplifier. Layout Considerations A properly designed PC board is an essential part of any RF/microwave circuit. Keep RF signal lines as short as possible to reduce losses, radiation, and inductance. For best performance, route the ground-pin traces directly to the exposed pad underneath the ______________________________________________________________________________________ 11 MAX2055 Digitally Controlled, Variable-Gain, Differential ADC Driver/Amplifier package. This pad should be connected to the ground plane of the board by using multiple vias under the device to provide the best RF/thermal conduction path. Solder the exposed pad on the bottom of the device package to a PC board exposed pad. The MAX2055 Evaluation Kit can be used as a reference for board layout. Gerber files are available upon request at www.maxim-ic.com. Power-Supply Bypassing Proper voltage-supply bypassing is essential for highfrequency circuit stability. Bypass each VCC pin with a 1000pF and 100pF capacitor. Connect the 100pF capacitor as close to the device as possible. Resistor R7 helps reduce switching transients. If switching transients are not a concern, R7 is not required. Therefore, connect pin 9 directly to VCC. Exposed Paddle RF Thermal Considerations The EP of the MAX2055’s 20-pin TSSOP-EP package provides a low thermal-resistance path to the die. It is important that the PC board on which the IC is mounted be designed to conduct heat from this contact. In addition, the EP provides a low-inductance RF ground path for the device. It is recommended that the EP be soldered to a ground plane on the PC board, either directly or through an array of plated via holes. Soldering the pad to ground is also critical for efficient heat transfer. Use a solid ground plane wherever possible. Chip Information Table 3. Attenuation Setting vs. GainControl Bits ATTENUATION B4 B3* B2 B1 B0 0 0 0 0 0 0 1 0 0 0 0 1 2 0 0 0 1 0 3 0 0 0 1 1 4 0 0 1 0 0 5 0 0 1 0 1 6 0 0 1 1 0 7 0 0 1 1 1 8 0 1 0 0 0 9 0 1 0 0 1 10 0 1 0 1 0 11 0 1 0 1 1 12 0 1 1 0 0 13 0 1 1 0 1 14 0 1 1 1 0 15 0 1 1 1 1 16 1 X 0 0 0 17 1 X 0 0 1 18 1 X 0 1 0 19 1 X 0 1 1 20 1 X 1 0 0 21 1 X 1 0 1 22 1 X 1 1 0 23 1 X 1 1 1 *Enabling B4 disables B3 and the minimum attenuation is 16dB. TRANSISTOR COUNT: 325 PROCESS: BiCMOS 12 ______________________________________________________________________________________ Digitally Controlled, Variable-Gain, Differential ADC Driver/Amplifier TSSOP4.40mm.EPS 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 ____________________ 13 © 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX2055 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.)