LMH6622 Dual Wideband, Low Noise, 160MHz, Operational Amplifiers General Description Features The LMH6622 is a dual high speed voltage feedback operational amplifier specifically optimized for low noise. A voltage noise specification of 1.6nV/ , a current noise specification 1.5pA/ , a bandwidth of 160MHz, and a harmonic distortion specification that exceeds 90dBc combine to make the LMH6622 an ideal choice for the receive channel amplifier in ADSL, VDSL, or other xDSL designs. The LMH6622 operates from ± 2.5V to ± 6V in dual supply mode and from +5V to +12V in single supply configuration. The LMH6622 is stable for AV ≥ 2 or AV ≤ −1. The fabrication of the LMH6622 on National Semiconductor’s advanced VIP10 process enables excellent (160MHz) bandwidth at a current consumption of only 4.3mA/amplifier. Packages for this dual amplifier are the 8-lead SOIC and the 8-lead MSOP. VS = ± 6V, TA = 25˚C, Typical values unless specified n Bandwidth (AV = +2) 160MHz ± 2.5V to ± 6V n Supply Voltage Range +5V to +12 n Slew rate 85V/µs n Supply current 4.3mA/amp n Input common mode voltage −4.75V to +5.7V ± 4.6V n Output Voltage Swing (RL = 100Ω) n Input voltage noise 1.6nV/ n Input current noise 1.5pA/ n Linear output current 90mA n Excellent harmonic distortion 90dBc Applications n n n n n xDSL receiver Low noise instrumentation front end Ultrasound preamp Active filters Cellphone basestation 20029226 xDSL Analog Front End © 2002 National Semiconductor Corporation DS200292 www.national.com LMH6622 Dual Wideband, Low Noise, 160MHz, Operational Amplifiers February 2002 LMH6622 Absolute Maximum Ratings Wave Soldering (10 sec) (Note 1) Storage Temperature Range If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Operating Ratings 2kV (Note 2) Machine Model 200V (Note 2) ± 1.2V VIN Differential + − Supply Voltage (V – V ) Voltage at Input Pins 13.2V +150˚C (Note 1) Supply Voltage (V+– V−) ± 2.25V to ± 6V Junction Temperature Range (Note 3), (Note 4) −40˚C to +85˚C Package Thermal Resistance (Note 4) (θJA) V+ +0.5V, V− −0.5V Soldering Information Infrared or Convection (20 sec) −65˚C to +150˚C Junction Temperature (Note 4) ESD Tolerance Human Body Model 260˚C 235˚C 8-pin SOIC 166˚C/W 8-pin MSOP 211˚C/W ± 6V Electrical Characteristics Unless otherwise specified, TJ = 25˚C, V+ = 6V, V− = −6V, VCM = 0V, AV = +2, RF = 500Ω, RL = 100Ω. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Min (Note 6) Typ (Note 5) Max (Note 6) Units Dynamic Performance fCL −3dB BW VO = 200mVPP 160 MHz BW0.1dB 0.1dB Gain Flatness VO = 200mVPP 30 MHz SR Slew Rate (Note 8) VO = 2VPP 85 V/µs TS Settling Time VO = 2VPP to ± 0.1% 40 VO = 2VPP to ± 1.0% 35 ns Tr Rise Time VO = 0.2V Step, 10% to 90% 2.3 ns Tf Fall Time VO = 0.2V Step, 10% to 90% 2.3 ns f = 100kHz 1.6 nV/ pA/ Distortion and Noise Response en Input Referred Voltage Noise in Input Referred Current Noise f = 100kHz 1.5 DG Differential Gain RL = 150Ω, RF = 470Ω, NTSC 0.03 % DP Differential Phase RL = 150Ω, RF = 470Ω, NTSC 0.03 deg HD2 2nd Harmonic Distortion fc = 1MHz, VO = 2VPP, RL = 100Ω −90 fc = 1MHz, VO = 2VPP, RL = 500Ω −100 HD3 MTPR 3rd Harmonic Distortion fc = 1MHz, VO = 2VPP, RL = 100Ω −94 fc = 1MHz, VO = 2VPP, RL = 500Ω −100 Upstream VO = 0.6 VRMS, 26kHz to 132kHz (see test circuit 5) −78 Downstream VO = 0.6 VRMS, 144kHz to 1.1MHz (see test circuit 5) −70 dBc dBc dBc Input Characteristics VOS Input Offset Voltage VCM = 0V TC VOS Input Offset Average Drift VCM = 0V (Note 7) IOS Input Offset Current VCM = 0V IB Input Bias Current VCM = 0V RIN Input Resistance CIN Input Capacitance www.national.com −1.2 −2 +0.2 +1.2 +2 −1 −1.5 −0.04 1 1.5 µA 4.7 10 15 µA −2.5 mV µV/˚C Common Mode 17 MΩ Differential Mode 12 kΩ Common Mode 0.9 pF Differential Mode 1.0 pF 2 (Continued) Unless otherwise specified, TJ = 25˚C, V+ = 6V, V− = −6V, VCM = 0V, AV = +2, RF = 500Ω, RL = 100Ω. Boldface limits apply at the temperature extremes. Symbol CMVR CMRR Parameter Conditions Input Common Mode Voltage Range CMRR ≥ 60dB Common-Mode Rejection Ratio Min (Note 6) Typ (Note 5) Max (Note 6) −4.75 −4.5 Units V 5.5 +5.7 Input Referred, VCM = −4.2 to +5.2V 80 75 100 dB 74 70 83 dB −75 dB Transfer Characteristics AVOL Large Signal Voltage Gain VO = 4VPP Xt Crosstalk f = 1MHz Output Characteristics VO Output Swing No Load, Positive Swing 4.8 4.6 No Load, Negative Swing RL = 100Ω, Positive Swing 5.2 −5.0 4.0 3.8 RL = 100Ω, Negative Swing −4.6 RO Output Impedance f = 1MHz Output Short Circuit Current Sourcing to Ground ∆VIN = 200mV (Note 3), (Note 9) 100 135 Sinking to Ground ∆VIN = −200mV (Note 3), (Note 9) 100 130 Output Current V 4.6 ISC IOUT −4.6 −4.4 −4 −3.8 Ω 0.08 mA 90 Sourcing, VO = +4.3V Sinking, VO = −4.3V mA Power Supply +PSRR Positive Power Supply Rejection Ratio Input Referred, VS = +5V to +6V 80 74 95 −PSRR Negative Power Supply Rejection Ratio Input Referred, VS = −5V to −6V 75 69 90 IS Supply Current (per amplifier) No Load 4.3 dB 6 6.5 mA ± 2.5V Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 2.5V, V− = −2.5V, VCM = 0V, AV = +2, RF = 500Ω, RL = 100Ω. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Min (Note 6) Typ (Note 5) Max (Note 6) Units Dynamic Performance fCL −3dB BW VO = 200mVPP 150 MHz BW0.1dB 0.1dB Gain Flatness VO = 200mVPP 20 MHz SR Slew Rate (Note 8) VO = 2VPP 80 V/µs TS Settling Time VO = 2VPP to ± 0.1% 45 VO = 2VPP to ± 1.0% 40 ns Tr Rise Time VO = 0.2V Step, 10% to 90% 2.5 ns Tf Fall Time VO = 0.2V Step, 10% to 90% 2.5 ns Distortion and Noise Response en Input Referred Voltage Noise f = 100kHz 1.7 nV/ in Input Referred Current Noise f = 100kHz 1.5 pA/ 3 www.national.com LMH6622 ± 6V Electrical Characteristics LMH6622 ± 2.5V Electrical Characteristics (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 2.5V, V− = −2.5V, VCM = 0V, AV = +2, RF = 500Ω, RL = 100Ω. Boldface limits apply at the temperature extremes. Symbol HD2 HD3 MTPR Parameter 2nd Harmonic Distortion Conditions Min (Note 6) Typ (Note 5) fc = 1MHz, VO = 2VPP, RL = 100Ω −88 fc = 1MHz, VO = 2VPP, RL = 500Ω −98 fc = 1MHz, VO = 2VPP, RL = 100Ω −92 fc = 1MHz, VO = 2VPP, RL = 500Ω −100 Upstream VO = 0.4VRMS,26kHz to 132kHz (see test circuit 5) −76 Downstream VO = 0.4VRMS,144kHz to 1.1MHz (see test circuit 5) −68 3rd Harmonic Distortion Max (Note 6) Units dBc dBc dBc Input Characteristics VOS Input Offset Voltage VCM = 0V TC VOS Input Offset Average Drift VCM = 0V (Note 7) IOS Input Offset Current VCM = 0V IB Input Bias Current VCM = 0V RIN Input Resistance CIN CMVR CMRR Input Capacitance −1.5 −2.3 +0.3 +1.5 +2.3 −1.5 −2.5 +0.01 1.5 2.5 µA 4.6 10 15 µA −2.5 mV µV/˚C Common Mode 17 MΩ Differential Mode 12 kΩ Common Mode 0.9 pF Differential Mode 1.0 pF Input Common Mode Voltage Range CMRR ≥ 60dB Common Mode Rejection Ratio −1.25 −1 V 2 +2.2 Input Referred, VCM = −0.7 to +1.7V 80 75 100 dB 74 82 dB −75 dB Transfer Characteristics AVOL Large Signal Voltage Gain VO = 1VPP Xt Crosstalk f = 1MHz Output Characteristics VO Output Swing No Load, Positive Swing 1.4 1.2 No Load, Negative Swing RL = 100Ω, Positive Swing 1.7 −1.5 1.2 1 1.5 RL = 100Ω, Negative Swing −1.4 0.1 RO Output Impedance f = 1MHz ISC Output Short Circuit Current Sourcing to Ground ∆VIN = 200mV (Note 3), (Note 9) 100 137 Sinking to Ground ∆VIN = −200mV (Note 3), (Note 9) 100 134 IOUT Output Current 90 Sourcing, VO = +0.8V Sinking, VO = −0.8V −1.2 −1 V −1.1 −0.9 Ω mA mA Power Supply +PSRR Positive Power Supply Rejection Ratio Input Referred, VS = +2.5V to +3V 78 72 93 −PSRR Negative Power Supply Rejection Ratio Input Referred, VS = −2.5V to −3V 75 70 88 www.national.com 4 dB dB LMH6622 ± 2.5V Electrical Characteristics (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 2.5V, V− = −2.5V, VCM = 0V, AV = +2, RF = 500Ω, RL = 100Ω. Boldface limits apply at the temperature extremes. Symbol IS Parameter Supply Current (per amplifier) Conditions No Load Min (Note 6) Typ (Note 5) Max (Note 6) 4.1 5.8 6.4 Units mA Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics. Note 2: Human body model, 1.5kΩ in series with 100pF. Machine model, 0Ω in series with 200pF. Note 3: Applies to both single-supply and split-supply operation. Continuous short circuit operation at elevated ambient temperature can result in exceeding the maximum allowed junction temperature of 150˚C. Note 4: The maximum power dissipation is a function of TJ(MAX), θJA and TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(MAX) − TA)/θJA. All numbers apply for packages soldered directly onto a PC board. Note 5: Typical values represent the most likely parametric norm. Note 6: All limits are guaranteed by testing or statistical analysis. Note 7: Offset voltage average drift is determined by dividing the change in VOS at temperature extremes into the total temperature change. Note 8: Slew rate is the slowest of the rising and falling slew rates. Note 9: Short circuit test is a momentary test. Output short circuit duration is infinite for VS ≤ ± 2.5V, at room temperature and below. For VS > ± 2.5V, allowable short circuit duration is 1.5ms. 5 www.national.com LMH6622 Typical Performance Characteristics Current and Voltage Noise vs. Frequency Current and Voltage Noise vs. Frequency 20029225 20029224 Frequency Response vs. Input Signal Level Frequency Response vs. Input Signal Level 20029202 20029203 Inverting Amplifier Frequency Response Non-Inverting Amplifier Frequency Response 20029246 www.national.com 20029247 6 LMH6622 Typical Performance Characteristics (Continued) Open Loop Gain and Phase Response Crosstalk vs. Frequency 20029201 20029205 PSRR vs. Frequency CMRR vs. Frequency 20029206 20029204 Positive Output Swing vs. Source Current Negative Output Swing vs. Sink Current 20029248 20029249 7 www.national.com LMH6622 Typical Performance Characteristics (Continued) Non-Inverting Small Signal Pulse Response VS = ± 2.5V, RL = 100Ω, AV = +2, RF = 500Ω Non-Inverting Small Signal Pulse Response VS = ± 6V, RL = 100Ω, AV = +2, RF = 500Ω 20029207 20029209 Non-Inverting Large Signal Pulse Response VS = ± 2.5V, RL = 100Ω, AV = +2, RF = 500Ω Non-Inverting Large Signal Pulse Response VS = ± 6V, RL = 100Ω, AV = +2, RF = 500Ω 20029208 20029210 Harmonic Distortion vs. Input Signal Level Harmonic Distortion vs. Input Signal Level 20029212 www.national.com 20029213 8 LMH6622 Typical Performance Characteristics (Continued) Harmonic Distortion vs. Frequency Harmonic Distortion vs. Frequency 20029214 20029215 Harmonic Distortion vs. Input Signal Level Harmonic Distortion vs. input Signal Level 20029216 20029217 Harmonic Distortion vs. Input Frequency Harmonic Distortion vs. Input Frequency 20029218 20029219 9 www.national.com LMH6622 Typical Performance Characteristics (Continued) Full Rate ADSL (DMT) Upstream MTPR @ VS = ± 2.5V Full Rate ADSL (DMT) Downstream MTPR @ VS = ± 2.5V 20029256 20029258 Full Rate ADSL (DMT) Upstream MTPR @ VS = ± 6V Full Rate ADSL (DMT) Downstream MTPR @ VS = ± 6V 20029257 www.national.com 20029259 10 LMH6622 Connection Diagram 8-Pin SOIC/MSOP 20029211 Top View Ordering Information Package Part Number Package Marking Transport Media NSC Drawing 8-Pin SOIC LMH6622MA LMH6622MA 95 Units per Rail M08A LMH6622MAX 8-Pin MSOP 2.5k Units Tape and Reel LMH6622MM A80A 1k Units Tape and Reel LMH6622MMX MUA08A 3.5k Units Tape and Reel Test Circuits 20029253 3) Voltage Noise RG = 1Ω for f ≤ 100kHz, RG = 20Ω for f > 100kHz 20029250 1) Non-Inverting Amplifier 20029252 4) Current Noise RG = 1Ω for f ≤ 100kHz, RG = 20Ω for f > 100kHz 20029251 2) CMRR 11 www.national.com LMH6622 Test Circuits (Continued) 20029255 5) Multitone Power Ratio, RF = 500Ω, RG = 174Ω, RL = 437Ω DSL Receive Channel Applications 20029223 FIGURE 1. ADSL Signal Description receiver pre-amp which is both low noise and highly linear for ADSL-standard operation. The LMH6622 is designed for the twin performance parameters of low noise and high linearity. Applications ranging from +5V to +12V or ± 2.5V to ± 6V are fully supported by the LMH6622. In Figure 2, the LMH6622 is used as an inverting summing amplifier to provide both received pre-amp channel gain and driver output signal cancellation, i.e., the function of a hybrid coupler. The LMH6622 is a dual, wideband operational amplifier designed for use as a DSL line receiver. In the receive band of a Customer Premises Equipment (CPE) ADSL modem it is possible that as many as 255 Discrete Multi-Tone (DMT) QAM signals will be present, each with its own carrier frequency, modulation, and signal level. The ADSL standard requires a line referred noise power density of -140dBm/Hz within the CPE receive band of 100KHz to 1.1MHz. The CPE driver output signal will leak into the receive path because of full duplex operation and the imperfections of the hybrid coupler circuit. The DSL analog front end must incorporate a www.national.com 12 LMH6622 DSL Receive Channel Applications (Continued) 20029227 FIGURE 2. ADSL Receive Applications Circuit 13 www.national.com LMH6622 DSL Receive Channel Applications (Continued) The two RS resistors are used to provide impedance matching through the 1:N transformer. Receive Channel Noise Calculation The circuit of Figure 2 also has the characteristic that it cancels noise power from the drive channel. The noise gain of the receive pre-amp is found to be: Where RL is the impedance of the twisted pair line. N is the turns ratio of the transformer. The resistors R2 and RF are used to set the receive gain of the pre-amp. The receive gain is selected to meet the ADC full-scale requirement of a DSL chipset. Resistor R1 and R2 along with RF are used to achieve cancellation of the output driver signal at the output of the receiver. Since the LMH6622 is configured as an inverting summing amplifier, VOUT is found to be, Noise power at each of the output of LMH6622: where The expression for V1 and V2 can be found by using superposition principle. When VS = 0, Vn Input referred voltage noise in Input referred current noise inon-inv Input referred non-inverting current noise iinv Input referred inverting current noise k Boltzmann’s constant, K = 1.38 x 10−23 T Resistor temperature in k R+ Source resistance at the non-inverting input to balance offset voltage, typically very small for this inverting summing applications For a voltage feedback amplifier, When VA = 0, Therefore, total output noise from the differential pre-amp is: Therefore, The factor ’2 ’ appears here because of differential output. Differential Analog-to-Digital Driver And then, Setting R1 = 2*R2 to cancel unwanted driver signal in the receive path, then we have We can also find that, And then 20029239 FIGURE 3. Circuit for Differential A/D Driver In conclusion, the peak-to-peak voltage to the ADC would be, www.national.com 14 LMH6622 DSL Receive Channel Applications (Continued) The LMH6622 is a low noise, low distortion high speed operational amplifier. The LMH6622 comes in either SOIC-8 or MSOP-8 packages. Because two channels are available in each package the LMH6622 can be used as a high dynamic range differential amplifier for the purpose of driving a high speed analog-to-digital converter. Driving a 1kΩ load, the differential amplifier of Figure 3 provides 20dB gain, a flat frequency response up to 6MHz, and harmonic distortion that is lower than 80dBc. This circuit makes use of a transformer to convert a single-ended signal to a differential signal. The input resistor RIN is chosen by the following equation, 20029222 FIGURE 5. Total Output Referred Noise Density The gain of this differential amplifier can be adjusted by RC and RF, 20029221 FIGURE 4. Frequency Response 15 www.national.com LMH6622 DSL Receive Channel Applications Device (Continued) Circuit Layout Considerations National Semiconductor suggests the copper patterns on the evaluation boards listed below as a guide for high frequency layout. These boards are also useful as an aid in device testing and characterization. As is the case with all highspeed amplifiers, accepted-practice RF design technique on the PCB layout is mandatory. Generally, a good high frequency layout exhibits a separation of power supply and ground traces from the inverting input and output pins. Parasitic capacitances between these nodes and ground will cause frequency response peaking and possible circuit oscillations (see Application Note OA-15 for more information). High quality chip capacitors with values in the range of 1000pF to 0.1µF should be used for power supply bypassing. One terminal of each chip capacitor is connected to the ground plane and the other terminal is connected to a point that is as close as possible to each supply pin as allowed by the manufacturer’s design rules. In addition, a tantalum capacitor with a value between 4.7µF and 10µF should be connected in parallel with the chip capacitor. Signal lines connecting the feedback and gain resistors should be as short as possible to minimize inductance and microstrip line effect. Input and output termination resistors should be placed as close as possible to the input/output pins. Traces greater than 1 inch in length should be impedance matched to the corresponding load termination. Symmetry between the positive and negative paths in the layout of differential circuitry should be maintained so as to minimize the imbalance of amplitude and phase of the differential signal. www.national.com Package Evaluation Board P/N LMH6622MA SOIC-8 CLC730036 LMH6622MM MSOP-8 CLC730123 These free evaluation boards are shipped when a device sample request is placed with National Semiconductor. Component value selection is another important parameter in working with high speed/high performance amplifiers. Choosing external resistors that are large in value compared to the value of other critical components will affect the closed loop behavior of the stage because of the interaction of these resistors with parasitic capacitances. These parasitic capacitors could either be inherent to the device or be a by-product of the board layout and component placement. Moreover, a large resistor will also add more thermal noise to the signal path. Either way, keeping the resistor values low will diminish this interaction. On the other hand, choosing very low value resistors could load down nodes and will contribute to higher overall power dissipation and worse distortion. Driving Capacitive Load Capacitive Loads decrease the phase margin of all op amps. The output impedance of a feedback amplifier becomes inductive at high frequencies, creating a resonant circuit when the load is capacitive. This can lead to overshoot, ringing and oscillation. To eliminate oscillation or reduce ringing, an isolation resistor can be placed between the load and the output. In general, the bigger the isolation resistor, the more damped the pulse response becomes. For initial evaluation, a 50Ω isolation resistor is recommended. 16 LMH6622 Physical Dimensions inches (millimeters) unless otherwise noted 8-Pin SOIC NS Package Number M08A 8-Pin MSOP NS Package Number MUA08A 17 www.national.com LMH6622 Dual Wideband, Low Noise, 160MHz, Operational Amplifiers Notes LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. National Semiconductor Corporation Americas Email: [email protected] www.national.com National Semiconductor Europe Fax: +49 (0) 180-530 85 86 Email: [email protected] Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: [email protected] National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507 National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.