LT6604-10 APPLICATIONS INFORMATIONInterfacing to the LT6604-10 operating with a single 3.3V supply and unity passband gain; the input signal is DC coupled. The common mode Note: The LT6604-10 contains two identical fi lters. The input voltage is 0.5V, and the differential input voltage is following applications information only refers to one fi lter. 2V The two fi lters are independent except that they share P-P. The common mode output voltage is 1.65V, and the differential output voltage is 2V the same negative supply voltage V–. The two fi lters P-P for frequencies below 10MHz. The common mode output voltage is determined can be used simultaneously by replicating the example by the voltage at V circuits. The referenced pin numbers correspond to the OCM. Since VOCM is shorted to VMID, the output common mode is the mid-supply voltage. In channel A fi lter. addition, the common mode input voltage can be equal The LT6604-10 channel requires two equal external resis- to the mid-supply voltage of VMID. tors, RIN, to set the differential gain to 402Ω/RIN. The inputs Figure 2 shows how to AC couple signals into the LT6604-10. to the fi lter are the voltages V + – IN and VIN presented to these In this instance, the input is a single-ended signal. AC external components, Figure 1. The difference between V + IN coupling allows the processing of single-ended or dif- and V – IN is the differential input voltage. The average of ferential signals with arbitrary common mode levels. The V + – IN and VIN is the common mode input voltage. Simi- 0.1μF coupling capacitor and the 402Ω gain setting resistor larly, the voltages V + – OUT and VOUT appearing at Pins 27 form a high pass fi lter, attenuating signals below 4kHz. and 29 of the LT6604-10 are the fi lter outputs. The differ- Larger values of coupling capacitors will proportionally ence between V + – OUT and VOUT is the differential output reduce this highpass 3dB frequency. voltage. The average of V + – OUT and VOUT is the common mode output voltage. Figure 1 illustrates the LT6604-10 3.3V 0.1μF V V 3 402Ω 25 – 4 3 VIN – 27 + 34 1/2 + V + OUT V 2 2 OUT LT6604-10 6 V + – IN 0.01μF – V 1 OUT + 2 – VOUT 1 V 29 IN + 402Ω 7 0 t 0 t – 660410 F01 VIN Figure 1 3.3V 0.1μF V V 0.1μF 25 402Ω 2 4 – 3 + 34 1/2 + 27 VOUT V + OUT 1 LT6604-10 2 6 V + 0.1μF IN 0.01μF – – VOUT 0 t + 2 – VOUT 1 V 29 IN + 402Ω 7 –1 0 660410 F02 Figure 2 660410fb 9