Datasheet LT6604-15 (Analog Devices) - 10
| Manufacturer | Analog Devices |
| Description | Dual Very Low Noise, Differential Amplifier and 15MHz Lowpass Filter |
| Pages / Page | 16 / 10 — APPLICATIONS INFORMATION. Evaluating the LT6604-15. Figure 3. Figure 4. … |
| File Format / Size | PDF / 213 Kb |
| Document Language | English |
APPLICATIONS INFORMATION. Evaluating the LT6604-15. Figure 3. Figure 4. Figure 5
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LT6604-15
APPLICATIONS INFORMATION
In Figure 3 the LT6604-15 is providing 12dB of gain. The voltage at VMID, for VS = 3.3V, is 1.65V. The voltage at the gain resistor has an optional 62pF in parallel to improve DAC pins is given by: the passband fl atness near 15MHz. The common mode R1 R1• R2 output voltage is set to 2V. V • • DAC = VMID +I R1 IN +R2+ 536 R1+R2 Use Figure 4 to determine the interface between the LT6604-15 and a current output DAC. The gain, or “tran- = 77mV +I • 45.3Ω simpedance,” is defi ned as A = V IN OUT/IIN. To compute the transimpedance, use the following equation: I + – IN is IIN or IIN . The transimpedance in this example is 49.8Ω. 536 • R1 A = (Ω) (R1+R2)
Evaluating the LT6604-15
By setting R1 + R2 = 536Ω, the gain equation reduces The low impedance levels and high frequency operation to A = R1 (Ω). of the LT6604-15 require some attention to the matching The voltage at the pins of the DAC is determined by R1, networks between the LT6604-15 and other devices. The R2, the voltage on V previous examples assume an ideal (0Ω) source impedance MID and the DAC output current. Consider Figure 4 with R1 = 49.9Ω and R2 = 487Ω. The and a large (1k) load resistance. Among practical examples 62pF 5V 0.1μF V V 133Ω 25 – 4 3 3 VIN – + + 34 1/2 + 27 VOUT VOUT 2 LT6604-15 2 6 0.01μF – – VOUT 500mVP-P (DIFF) + 2 – VOUT 1 1 V 29 IN + V + 133Ω IN 7 0 t – + 0 t V 660415 F03 IN – 2V 62pF
Figure 3
CURRENT 3.3V 2.5V OUTPUT 0.1μF 0.1μF DAC COILCRAFT COILCRAFT NETWORK NETWORK – 25 I TTWB-1010 TTWB-16A IN R2 4 ANALYZER ANALYZER – 25 27 SOURCE 1:1 523Ω 4 4:1 INPUT 34 1/2 + V + 402Ω OUT – 27 R1 34 1/2 + 0.01μF 6 LT6604-15 50Ω LT6604-15 52.3Ω 6 50Ω I + R2 – IN 2 – + VOUT 29 2 – + 29 7 R1 402Ω 523Ω 7 0.1μF 660415 F05 V + – OUT – VOUT 536 • R1 = I + – I – R1 + R2 660415 F04 IN IN –2.5V
Figure 4 Figure 5
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APPLICATIONS INFORMATION
In Figure 3 the LT6604-15 is providing 12dB of gain. The voltage at VMID, for VS = 3.3V, is 1.65V. The voltage at the gain resistor has an optional 62pF in parallel to improve DAC pins is given by: the passband fl atness near 15MHz. The common mode R1 R1• R2 output voltage is set to 2V. V • • DAC = VMID +I R1 IN +R2+ 536 R1+R2 Use Figure 4 to determine the interface between the LT6604-15 and a current output DAC. The gain, or “tran- = 77mV +I • 45.3Ω simpedance,” is defi ned as A = V IN OUT/IIN. To compute the transimpedance, use the following equation: I + – IN is IIN or IIN . The transimpedance in this example is 49.8Ω. 536 • R1 A = (Ω) (R1+R2)
Evaluating the LT6604-15
By setting R1 + R2 = 536Ω, the gain equation reduces The low impedance levels and high frequency operation to A = R1 (Ω). of the LT6604-15 require some attention to the matching The voltage at the pins of the DAC is determined by R1, networks between the LT6604-15 and other devices. The R2, the voltage on V previous examples assume an ideal (0Ω) source impedance MID and the DAC output current. Consider Figure 4 with R1 = 49.9Ω and R2 = 487Ω. The and a large (1k) load resistance. Among practical examples 62pF 5V 0.1μF V V 133Ω 25 – 4 3 3 VIN – + + 34 1/2 + 27 VOUT VOUT 2 LT6604-15 2 6 0.01μF – – VOUT 500mVP-P (DIFF) + 2 – VOUT 1 1 V 29 IN + V + 133Ω IN 7 0 t – + 0 t V 660415 F03 IN – 2V 62pF
Figure 3
CURRENT 3.3V 2.5V OUTPUT 0.1μF 0.1μF DAC COILCRAFT COILCRAFT NETWORK NETWORK – 25 I TTWB-1010 TTWB-16A IN R2 4 ANALYZER ANALYZER – 25 27 SOURCE 1:1 523Ω 4 4:1 INPUT 34 1/2 + V + 402Ω OUT – 27 R1 34 1/2 + 0.01μF 6 LT6604-15 50Ω LT6604-15 52.3Ω 6 50Ω I + R2 – IN 2 – + VOUT 29 2 – + 29 7 R1 402Ω 523Ω 7 0.1μF 660415 F05 V + – OUT – VOUT 536 • R1 = I + – I – R1 + R2 660415 F04 IN IN –2.5V
Figure 4 Figure 5
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