350MHz, Ultra-Low-Noise Op Amps

Transcription

1 9-442; Rev ; /95 EVALUATION KIT AVAILABLE 35MHz, Ultra-Low-Noise Op Amps General Description The / op amps combine high-speed performance with ultra-low-noise performance. The is compensated for closed-loop gains of 5V/V, while the is stable in closed-loop gains of V/V or greater. The / require only ma of supply current while delivering a 35MHz or a 3MHz bandwidth, respectively. Voltage noise is an ultra-low.75nv/ Hz, while a low-distortion architecture provides a spurious-free dynamic range (SFDR) of 63dB at 5MHz. These high-speed op amps have a wide output voltage swing of ±3.2V and a high current-drive capability of 8mA. Applications Ultra-Low-Noise ADC Preamp Ultrasound Low-Noise Preamplifier High-Performance Receivers Active Filters Pulse/RF Amplifier Features 35MHz -3dB Bandwidth () 275V/µs Slew Rate () 5V/µs Slew Rate () ns Settling Time to.%.75nv/ Hz Voltage Noise High Output Drive: 8mA Ordering Information PART ESA ESA TEMP. RANGE -4 C to +85 C -4 C to +85 C P-PACKAGE 8 SO 8 SO / Typical Application Circuit Pin Configuration +5V TOP VIEW.µF pf PUT.µF pf 8 to -BIT HIGH-SPEED ADC N.C N.C. V CC -5V V EE 4 5 N.C. R G 27Ω R F Ω SO ADC BUFFER WITH GA (A VCL = V/V) Maxim Integrated Products Call toll free for free samples or literature.

2 35MHz, Ultra-Low-Noise Op Amps / ABSOLUTE MAXIMUM RATGS Power-Supply Voltage (V CC to V EE)...2V Voltage on Any Pin to Ground or Any Other Pin...V CC to V EE Short-Circuit Duration (V to )...Continuous Continuous Power Dissipation (T A = +7 C) SO (derate 5.88mW/ C above +7 C)...47mW 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. ELECTRICAL CHARACTERISTICS (V CC = 5V, V EE = -5V, T A = T M to T MAX, typical values are at T A = +25 C, unless otherwise noted.) PARAMETER DC SPECIFICATIONS Input Offset Voltage Input Offset Voltage Drift Input Bias Current Input Offset Current Common-Mode Input Resistance SYMBOL V OS TCV OS I B I OS R CM V = V V = V V = V, V = -V OS V = V, V = -V OS Either input Operating Temperature Range ESA/ESA...-4 C to +85 C Storage Temperature Range C to + C Junction Temperature...+ C Lead Temperature (soldering, sec)...+3 C CONDITIONS M TYP MAX UNITS mv µv/ C µa µa MΩ Common-Mode Input Capacitance C CM Either input pf Input Voltage Noise e n f = khz.75 nv/ Hz Integrated Voltage Noise E nrms f = MHz to MHz 9.5 µv RMS Input Current Noise I n f = khz 2.5 pa/ Hz Integrated Current Noise I nrms f = MHz to MHz 3 na RMS Common-Mode Input Voltage V CM V Common-Mode Rejection CMR V CM = ±2.5V 7 db Power-Supply Rejection PSR V S = ±4.5V to ±5.5V 75 db Open-Loop Voltage Gain A VOL V = ±2.V, V CM = V R L = R L = Ω 8 8 db Supply Current I S V = V 9 ma Output Voltage Swing V R L = R L = Ω ±3.2 ±3.8 ±3. ±3.5 V Output Current Drive I R L = 3Ω, T A = C to +85 C 65 8 ma Short-Circuit Output Current I SC Short to ground 9 ma 2

3 35MHz, Ultra-Low-Noise Op Amps ELECTRICAL CHARACTERISTICS (continued) (V CC = 5V, V EE = -5V, T A = T M to T MAX, typical values are at T A = +25 C, unless otherwise noted.) PARAMETER AC SPECIFICATIONS -3dB Bandwidth.dB Bandwidth Slew Rate Settling Time Rise/Fall Times Differential Gain Differential Phase Input Capacitance Output Impedance Spurious-Free Dynamic Range Two-Tone Third-Order Intercept SYMBOL BW -3dB BW.dB SR t S t R, t F DG DP C Z SFDR IP3 V.V RMS, A VCL = +5, A VCL = + -2V V 2V -V V V, R L = Ω, to.% -V V V, R L = Ω, to.% f = 3.58MHz f = 3.58MHz f = MHz f C = MHz CONDITIONS % to 9%, -2V V 2V, R L = Ω % to 9%, -5mV V 5mV, R L = Ω f C = 5MHz, V = 2Vp-p, A VCL = +5, A VCL = +, A VCL = +5, A VCL = +, A VCL = +5, A VCL = + M TYP MAX UNITS MHz MHz V/µs ns ns % degrees pf Ω dbc dbm / 3

4 35MHz, Ultra-Low-Noise Op Amps / Typical Operating Characteristics (V CC = +5V, V EE = -5V, R L = Ω, T A = +25 C, unless otherwise noted.) GA (db) SMALL-SIGNAL GA (A VCL = +5, +6) A VCL = +6 A VCL = +5 9.M M M M /7- GA (db) SMALL-SIGNAL GA (A VCL = +).M M M M /7-2 GA (db) SMALL-SIGNAL GA (A VCL = +) M M M M /7-3 GA (db) SMALL-SIGNAL GA (A VCL = +) /7-4 VOLTAGE NOISE (nv/ Hz) VOLTAGE NOISE /7-5 CURRENT NOISE (pa/ Hz) CURRENT NOISE /7-6 2.M M M M. k k k M M FREQUENCY (Hz, Log) k k k M M FREQUENCY (Hz, Log) SMALL-SIGNAL PULSE RESPONSE (A VCL = +5) SMALL-SIGNAL PULSE RESPONSE (A VCL = +) LARGE-SIGNAL PULSE RESPONSE (A VCL = +5) /7-7 /7-8 /7-9 VOLTAGE (mv/div) VOLTAGE (mv/div) VOLTAGE (V/div) TIME (ns/div) TIME (ns/div) TIME (ns/div) 4

5 35MHz, Ultra-Low-Noise Op Amps Typical Operating Characteristics (continued) (V CC = +5V, V EE = -5V, R L = Ω, T A = +25 C, unless otherwise noted.) VOLTAGE (V/div) VOLTAGE (V/div) LARGE-SIGNAL PULSE RESPONSE (A VCL = +) TIME (ns/div) LARGE-SIGNAL PULSE RESPONSE (A VCL = +) TIME (ns/div) /7- /7-3 VOLTAGE (mv/div) VOLTAGE (V/div) SMALL-SIGNAL PULSE RESPONSE (A VCL = +) TIME (ns/div) LARGE-SIGNAL PULSE RESPONSE (A VCL = +) TIME (ns/div) /7- /7- VOLTAGE (mv/div) RESISTANCE (Ω) 7k 2.2k SMALL-SIGNAL PULSE RESPONSE (A VCL = +) TIME (ns/div) CLOSED-LOOP PUT IMPEDANCE.7.M M M M /7-2 /7- / PSR (db) POWER-SUPPLY REJECTION /7- CMR (db) COMMON-MODE REJECTION /7-7 CMR (db) COMMON-MODE REJECTION /7- -6.M M M M -5 k k M M M -4 3k k M M M 5

6 35MHz, Ultra-Low-Noise Op Amps / Typical Operating Characteristics (continued) (V CC = +5V, V EE = -5V, R L = Ω, T A = +25 C, unless otherwise noted.) THIRD-ORDER TERCEPT (dbm) TWO-TONE THIRD-ORDER TERCEPT FREQUENCY (MHz) HARMONIC DISTORTION (A VCL = +) -.M M M M MHz HARMONIC DISTORTION vs. PUT SWG A VCL = +5 R L = Ω PUT SWG (V P-P) /7-9 /7- / HARMONIC DISTORTION (A VCL = +5) V O = 2Vp-p R L = Ω -. FREQUENCY (MHz) MHz HARMONIC DISTORTION vs. LOAD RESISITANCE A VCL = +5 V O = 2Vp-p LOAD RESISTANCE (Ω) 5MHz HARMONIC DISTORTION vs. PUT SWG A VCL = + R L = Ω /7- / PUT SWG (V P-P) /7-26 DIFF. GA (%) DIFF. PHASE ( ) HARMONIC DISTORTION (A VCL = +) V O = 2Vp-p R L = Ω -. FREQUENCY (MHz) MHz HARMONIC DISTORTION vs. LOAD RESISTANCE A VCL = + V O = 2Vp-p LOAD RESISTANCE (Ω) DIFFERENTIAL GA AND PHASE R L = Ω /7-2 /7- IRE.3.2 R L = Ω /7-27 IRE 6

7 35MHz, Ultra-Low-Noise Op Amps Typical Operating Characteristics (continued) (V CC = +5V, V EE = -5V, R L = Ω, T A = +25 C, unless otherwise noted.) DIFF. GA (%) DIFF. PHASE ( ) NEGATIVE PUT VOLTAGE (V) DIFFERENTIAL GA AND PHASE IRE IRE NEGATIVE PUT VOLTAGE SWG vs. TEMPERATURE R L = Ω R L = TEMPERATURE ( C) /7-3 /7-28 PUT SWG (VP-P) SUPPLY CURRENT (ma) PUT SWG vs. LOAD RESISTANCE LOAD RESISTANCE (Ω) POWER-SUPPLY CURRENT vs. TEMPERATURE I CC - I EE TEMPERATURE ( C) /7-29 /7-32 POSITIVE PUT VOLTAGE (V) PUT BIAS CURRENT (µa) POSITIVE PUT VOLTAGE SWG vs. TEMPERATURE R L = R L = Ω TEMPERATURE ( C) PUT BIAS CURRENT vs. TEMPERATURE TEMPERATURE ( C) /7-3 /7-33 / PUT OFFSET CURRENT (µa) PUT OFFSET CURRENT vs. TEMPERATURE TEMPERATURE ( C) /7-34 PUT OFFSET VOLTAGE (mv) PUT OFFSET VOLTAGE vs. TEMPERATURE TEMPERATURE ( C) /7-35 7

8 35MHz, Ultra-Low-Noise Op Amps / Pin Description P, 5, NAME N.C. - + V EE V CC No Connection, not internally connected Inverting Input Noninverting Input Negative Power Supply, connect to -5V Amplifier Output FUNCTION Positive Power Supply, connect to +5V General Description Choosing Resistor Values The values of the gain-setting feedback and input resistors are important design considerations. Large resistor values will increase voltage noise, and will interact with the amplifier s input and PC board capacitance to generate undesirable poles and zeros, which can decrease bandwidth or cause oscillations. For example, a noninverting gain of +5 (), using a kω feedback resistor combined with 2pF of input capacitance and.5pf of board capacitance, will cause a feedback pole at 3MHz. If this pole is within the anticipated amplifier bandwidth, it will jeopardize stability. Reducing the kω feedback resistor to 4Ω will extend the pole frequency to 8GHz, but could limit output swing by adding 5Ω in parallel with the amplifier s load. Clearly the selection of resistor values must be tailored to the specific application. The / are ultra-low-noise, high-bandwidth op amps. The output noise voltage can be dominated by resistor thermal noise, so keep the feedback and input resistors small. Setting the input resistor to 3Ω and choosing the feedback resistor to suit the gain will provide excellent AC performance without significantly degrading noise performance. Driving Capacitive Loads The / are optimized for AC performance. They are not designed to drive highly reactive loads. Reactive loads will decrease phase margin and may produce excessive ringing and oscillation. Figure a shows a circuit that eliminates this problem, and Figure b is a graph of the optimal isolation resistor (RS) vs. capacitive load. Figures 2a and 2b show how a capacitive load causes excessive peaking of the amplifier s bandwidth if the capacitive load is not isolated (RS) from the amplifier. A small isolation resistor (usually Ω to Ω) placed before the reactive load prevents ringing and oscillation. At higher capacitive loads, AC performance will be controlled by the interaction of the load capacitance and isolation resistor. Figures 3a and 3b show the effect of an isolation resistor on the / closed-loop response. Coaxial cable and other transmission lines are easily driven when terminated at both ends with their characteristic impedance. When driving back-terminated transmission lines, the capacitance of the transmission line is essentially eliminated. R G 3Ω R F 3 25 /7-B V R S C L R L RESISTANCE (Ω) 5 PART RF (Ω) 27 GA (V/V) +5 + Figure a. Using an Isolation Resistor for High Capacitive Loads CAPACITANCE (pf) Figure b. Optimal Isolation Resistor (R S) vs. Capacitive Load 8

9 35MHz, Ultra-Low-Noise Op Amps CLOSED-LOOP GA (db) 2 8 R S = Ω A VCL = +5 6.M M M M C L = pf C L = 5pF /7-2A CLOSED-LOOP GA (db) 26 2 R S = Ω A VCL = + C L = pf C L = pf C L = 5pF.M M M M /7-2B / Figure 2a. Response vs. Capacitive Load No Resistive (R S) Isolation (circuit shown in Figure ) Figure 2b. Response vs. Capacitive Load No Isolation (R S) Resistor (circuit shown in Figure ) CLOSED-LOOP GA (db) 2 8 C L = pf A VCL = +5 R S = 4.7Ω R S = Ω R S = Ω /7-3A CLOSED-LOOP GA (db) 26 C L = pf A VCL = + R S = 2.2Ω R S = Ω R S = Ω /7-3B M M M M.M M M M Figure 3a. Response vs. Capacitive Load with Resistive (R S) Isolation (circuit shown in Figure ) Figure 3b. Response vs. Capacitive Load with Resistive (R S) Isolation (circuit shown in Figure ) 9

10 / 35MHz, Ultra-Low-Noise Op Amps Chip Information Package Information TRANSISTOR COUNT: 55 DIM A A B C E e H L M MAX M MAX CHES MILLIMETERS 2-4A Narrow SO SMALL-LE PACKAGE (. in.) DIM D D D M MAX M MAX CHES MILLIMETERS PS L -8 H E D e A A C.mm.4in. B

11 35MHz, Ultra-Low-Noise Op Amps /

12 35MHz, Ultra-Low-Noise Op Amps / 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. 2 Maxim Integrated Products, San Gabriel Drive, Sunnyvale, CA 9486 (48) Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.