link to page 27 Data SheetADA4817-1/ADA4817-2HIGH SPEED JFET INPUT INSTRUMENTATION The system bandwidth for G = 1 is 400 MHz. For gains higher AMPLIFIER than 2, the bandwidth is set by the preamp, and it can be Figure 66 shows an example of a high speed instrumentation approximated by amplifier with a high input impedance using the ADA4817-1/ In-amp−3 dB = (fCR × RG)/(2 × RF) ADA4817-2. The dc transfer function is The match of resistor ratios, R1:R2 to R3:R4, primarily determine the common-mode rejection of the in-amp and it is estimated by V (V V ) 2R = − 1+ F (16) OUT N P G R V (δ1− δ2) O = (17) For G = 1, it is recommended that the feedback resistors for the CM V (1+ δ ) 1 δ2 two preamps be set to 0 Ω and the gain resistor be open. The summing junction impedance for the preamps is equal to RF | 0.5(RG). Keep this value relatively low to improve the bandwidth response like in the previous example. VCC0.1µF10µFRS1R2V350ΩNADA4817-2 U1VCC0.1µF10µFVEE0.1µF10µFR1350ΩRF = 500ΩADA4817-1VORGR3RF = 500Ω350Ω0.1µF10µFVCCR4V350ΩEE0.1µF10µFADA4817-2RU2S20.1µF10µFVP 050 VEE 07756- Figure 66. High Speed Instrumentation Amplifier Rev. G | Page 27 of 31 Document Outline FEATURES APPLICATIONS CONNECTION DIAGRAMS TABLE OF CONTENTS REVISION HISTORY GENERAL DESCRIPTION SPECIFICATIONS ±5 V OPERATION 5 V OPERATION ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE MAXIMUM SAFE POWER DISSIPATION ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS TEST CIRCUITS THEORY OF OPERATION CLOSED-LOOP FREQUENCY RESPONSE NONINVERTING CLOSED-LOOP FREQUENCY RESPONSE INVERTING CLOSED-LOOP FREQUENCY RESPONSE WIDEBAND OPERATION DRIVING CAPACITIVE LOADS THERMAL CONSIDERATIONS POWER-DOWN OPERATION CAPACITIVE FEEDBACK HIGHER FREQUENCY ATTENUATION LAYOUT, GROUNDING, AND BYPASSING CONSIDERATIONS SIGNAL ROUTING POWER SUPPLY BYPASSING GROUNDING EXPOSED PAD LEAKAGE CURRENTS INPUT CAPACITANCE INPUT-TO-INPUT/OUTPUT COUPLING APPLICATIONS INFORMATION LOW DISTORTION PINOUT WIDEBAND PHOTODIODE PREAMP HIGH SPEED JFET INPUT INSTRUMENTATION AMPLIFIER ACTIVE LOW-PASS FILTER (LPF) OUTLINE DIMENSIONS ORDERING GUIDE