link to page 8 link to page 8 AD706C1R1R2C3+VS1M1M0.1FR3R4INPUT3 +1/2C21M1M815 +AD7061/22 –4C47OUTPUTAD706*WITHOUT THE NETWORK,0.16 –FPINS 1 AND 2, AND 6 AND 7 OF THE AD706 ARE TIED–VSTOGETHER.R6C6CAPACITORS C1 AND C2R5C52M0.01FARE SOUTHERN ELECTRONICS2M0.01FMPCC, POLYCARB5%, 50VOPTIONAL BALANCE RESISTOR NETWORKS* Figure 7. 1 Hz, 4-Pole Active Filter 1 Hz, 4-Pole, Active Filter180V Figure 7 shows the AD706 in an active filter application. An important characteristic of the AD706 is that both the input bias 120WITHOUT OPTIONALBALANCE RESISTOR, R3 current, input offset current, and their drift remain low over most of the op amp’s rated temperature range. Therefore, for 60 most applications, there is no need to use the normal balancing resistor. Adding the balancing resistor enhances performance at 0 high temperatures, as shown by Figure 8. WITH OPTIONAL BALANCERESISTOR, R3–60–120OFFSET VOLTAGE OF FILTER CIRCUIT (RTI) – –180–4004080120TEMPERATURE –C Figure 8. VOS vs. Temperature Performance of the 1 Hz Filter Table II. 1 Hz, 4-Pole, Low Pass Filter Recommended Component ValuesSection 1Section 2Desired LowFrequencyFrequencyC1C2C3C4Pass Response(Hz)Q(Hz)Q(F)(F)(F)(F) Bessel 1.43 0.522 1.60 0.806 0.116 0.107 0.160 0.0616 Butterworth 1.00 0.541 1.00 1.31 0.172 0.147 0.416 0.0609 0.1 dB Chebychev 0.648 0.619 0.948 2.18 0.304 0.198 0.733 0.0385 0.2 dB Chebychev 0.603 0.646 0.941 2.44 0.341 0.204 0.823 0.0347 0.5 dB Chebychev 0.540 0.705 0.932 2.94 0.416 0.209 1.00 0.0290 1.0 dB Chebychev 0.492 0.785 0.925 3.56 0.508 0.206 1.23 0.0242 NOTE Specified Values are for a –3 dB point of 1.0 Hz. For other frequencies simply scale capacitors C1 through C4 directly, i.e. for 3 Hz Bessel response, C1 = 0.0387 µF, C2 = 0.0357 µF, C3 = 0.0533 µF, C4 = 0.0205 µF. REV. G –8– Document Outline FEATURES APPLICATIONS CONNECTION DIAGRAM GENERAL DESCRIPTION PRODUCT HIGHLIGHTS SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS METALIZATION PHOTOGRAPH TYPICAL PERFORMANCE CHARACTERISTICS 1 HZ, 4-POLE, ACTIVE FILTER OUTLINE DIMENSIONS ORDERING GUIDE REVISION HISTORY