Datasheet LT1567 (Analog Devices) - 8
| Manufacturer | Analog Devices |
| Description | 1.4nV/√Hz 180MHz Filter Building Block |
| Pages / Page | 16 / 8 — APPLICATIO S I FOR ATIO. Functional Description. LT1567 Free Design … |
| File Format / Size | PDF / 208 Kb |
| Document Language | English |
APPLICATIO S I FOR ATIO. Functional Description. LT1567 Free Design Software. Gain vs Frequency
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LT1567
U U W U APPLICATIO S I FOR ATIO Functional Description
addressing the different sensitivities to these effects when used as a filter section. This combination produces The LT1567 contains two low noise rail-to-rail output, a low noise filter with better distortion performance than wideband operational amplifiers, one of them connected would be possible with identical amplifiers. internally as a unity-gain inverter. These two amplifiers can form a second order multiple feedback filter configu-
LT1567 Free Design Software
ration (Figure 1) for megahertz signal frequencies, with exceptionally low total noise. The amplifier in the dedi- A spreadsheet-based design tool is available at cated inverter (INV) is optimized for better high fre- www.linear.com for designing lowpass and bandpass quency linearity while the uncommitted operational filters using the LT1567. amplifier (OA) is optimized for lower input noise voltage, V – OUT 1 6 DESIGN EQUATIONS: R2 C1 LT1567 R2 (GAIN = ) 600Ω GAIN = 1 AND fC ≤ 1MHz R1 600Ω R1 R3 2 – fC IS THE FILTER’S CUTOFF FREQUENCY VIN 1 R1 = R2, C1 = C2, C1 C2 ≤ 1000 • f – C + 7 1 BUTTERWORTH R2 = 0.1µF V + 4.44 • C1 • f OUT C 3 + R2 R3 = 2 7pF 1 5 150Ω CHEBYSHEV 0.25dB RIPPLE R2 = 5.65 • C1 • fC V+ R2 V– R3 = 2.62 8 0.1µF 4 0.1µF V+ V– 1567 F01a
Gain vs Frequency
3 0 CHEBYSHEV –3 BUTTERWORTH –6 f 1 O = 2π√R2R3 C2 –9 –12 R2 Q = R3 –15 GAIN + 1 GAIN (dB) –18 (2πf TRANSFER FUNCTION H(s) = O)2 (2πfO) –21 s2 + s + (2πf Q O)2 –24 –27 –30 100k 1M 10M FREQUENCY (Hz) 1567 F01b GAIN IS MEASURED TO EITHER OUTPUT ALONE. IF OUTPUT USED DIFFERENTIALLY, V + – OUT – VOUT = 2× VIN
Figure 1. 2nd Order Lowpass Filter and Gain Response for fC = 1MHz (Butterworth: C1 = C2 = 390pF, R1 = R2 = 576
Ω
, R3 = 280
Ω
Chebyshev: C1 = C2 = 390pF, R1 = R2 = 453
Ω
, R3 = 174
Ω
)
1567fa 8
U U W U APPLICATIO S I FOR ATIO Functional Description
addressing the different sensitivities to these effects when used as a filter section. This combination produces The LT1567 contains two low noise rail-to-rail output, a low noise filter with better distortion performance than wideband operational amplifiers, one of them connected would be possible with identical amplifiers. internally as a unity-gain inverter. These two amplifiers can form a second order multiple feedback filter configu-
LT1567 Free Design Software
ration (Figure 1) for megahertz signal frequencies, with exceptionally low total noise. The amplifier in the dedi- A spreadsheet-based design tool is available at cated inverter (INV) is optimized for better high fre- www.linear.com for designing lowpass and bandpass quency linearity while the uncommitted operational filters using the LT1567. amplifier (OA) is optimized for lower input noise voltage, V – OUT 1 6 DESIGN EQUATIONS: R2 C1 LT1567 R2 (GAIN = ) 600Ω GAIN = 1 AND fC ≤ 1MHz R1 600Ω R1 R3 2 – fC IS THE FILTER’S CUTOFF FREQUENCY VIN 1 R1 = R2, C1 = C2, C1 C2 ≤ 1000 • f – C + 7 1 BUTTERWORTH R2 = 0.1µF V + 4.44 • C1 • f OUT C 3 + R2 R3 = 2 7pF 1 5 150Ω CHEBYSHEV 0.25dB RIPPLE R2 = 5.65 • C1 • fC V+ R2 V– R3 = 2.62 8 0.1µF 4 0.1µF V+ V– 1567 F01a
Gain vs Frequency
3 0 CHEBYSHEV –3 BUTTERWORTH –6 f 1 O = 2π√R2R3 C2 –9 –12 R2 Q = R3 –15 GAIN + 1 GAIN (dB) –18 (2πf TRANSFER FUNCTION H(s) = O)2 (2πfO) –21 s2 + s + (2πf Q O)2 –24 –27 –30 100k 1M 10M FREQUENCY (Hz) 1567 F01b GAIN IS MEASURED TO EITHER OUTPUT ALONE. IF OUTPUT USED DIFFERENTIALLY, V + – OUT – VOUT = 2× VIN
Figure 1. 2nd Order Lowpass Filter and Gain Response for fC = 1MHz (Butterworth: C1 = C2 = 390pF, R1 = R2 = 576
Ω
, R3 = 280
Ω
Chebyshev: C1 = C2 = 390pF, R1 = R2 = 453
Ω
, R3 = 174
Ω
)
1567fa 8
