Datasheet LT1024 (Analog Devices) - 7
| Manufacturer | Analog Devices |
| Description | Dual, Matched Picoampere, Microvolt Input, Low Noise Op Amp |
| Pages / Page | 12 / 7 — APPLICATIO S I FOR ATIO. Advantages of Matched Dual Op Amps. Three Op Amp … |
| File Format / Size | PDF / 179 Kb |
| Document Language | English |
APPLICATIO S I FOR ATIO. Advantages of Matched Dual Op Amps. Three Op Amp Instrumentation Amplifier
Model Line for this Datasheet
Text Version of Document
LT1024
U U W U APPLICATIO S I FOR ATIO
The LT1024 may be inserted directly into OP-10, OP-207 these two currents (I + OS ) is the offset current of the or 0P227 sockets with or without removal of external instrumentation amplifier. Common mode and power nulling components. supply rejections will be dependent only on the match between the two amplifiers (assuming perfect resistor The LT1024 is specified over a wide range of power supply matching). voltages from ±2V to ±18V. Operation with lower supplies is possible down to ±1.2V (two NiCad batteries). The concepts of common mode and power supply rejec- tion ratio match (∆CMRR and ∆PSRR) are best demon-
Advantages of Matched Dual Op Amps
strated with a numerical example: In many applications, the performance of a system Assume CMRRA = +1.0µV/V or 120dB depends on the matching between two operational and CMRRB = +0.5µV/V or 126dB, amplifiers rather than the individual characteristics of the then ∆CMRR = 0.5µV/V or 126dB two op amps. Two or three op amp instrumentation if CMRRB = –0.5µV/V, which is still 126dB, amplifiers, tracking voltage references, and low drift active then ∆CMRR = 1.5µV/V or 116.5dB. filters are some of the circuits requiring matching between Typical performance of the instrumentation amplifier: two op amps. Input offset voltage = 25µV. The well-known triple op amp configuration illustrates Input bias current = 30pA. these concepts. Output offset is a function of the dif- Input resistance = 1012Ω. ference between the offsets of the two halves of the Input offset current = 30pA. LT1024. This error cancellation principle holds for a Input noise = 0.7µVP-P. considerable number of input-referred parameters in Power bandwidth (VO = ±10V) = 80kHz. addition to offset voltage and its drift with temperature. Clearly, the LT1024, by specifying and guaranteeing all of Input bias current will be the average of the two these matching parameters, can significantly improve the noninverting input currents (I + B ). The difference between performance of matching dependent circuits.
Three Op Amp Instrumentation Amplifier
15V R4 R6 4 14 100Ω 10k –INPUT + A 13 1% 1% 1/2 LT1024 3 R1 – 12 10k 1% –15V 15V R3 C1 2 7 2.1k 100pF – 1% R10 6 LT1037 OUTPUT 100k R8 3 200 + Ω 4 15V R2 –15V R5 10k 10 7 100Ω 1% GAIN = 1000 – 1% B 6 1/2 LT1024 R7 11 +INPUT + 9.76k 5 1% –15V R9 500Ω TRIM R8 FOR GAIN TRIM R9 FOR DC COMMON MODE REJECTION TRIM R10 FOR AC COMMON MODE REJECTION LT1024 • AI01 1024fa 7
U U W U APPLICATIO S I FOR ATIO
The LT1024 may be inserted directly into OP-10, OP-207 these two currents (I + OS ) is the offset current of the or 0P227 sockets with or without removal of external instrumentation amplifier. Common mode and power nulling components. supply rejections will be dependent only on the match between the two amplifiers (assuming perfect resistor The LT1024 is specified over a wide range of power supply matching). voltages from ±2V to ±18V. Operation with lower supplies is possible down to ±1.2V (two NiCad batteries). The concepts of common mode and power supply rejec- tion ratio match (∆CMRR and ∆PSRR) are best demon-
Advantages of Matched Dual Op Amps
strated with a numerical example: In many applications, the performance of a system Assume CMRRA = +1.0µV/V or 120dB depends on the matching between two operational and CMRRB = +0.5µV/V or 126dB, amplifiers rather than the individual characteristics of the then ∆CMRR = 0.5µV/V or 126dB two op amps. Two or three op amp instrumentation if CMRRB = –0.5µV/V, which is still 126dB, amplifiers, tracking voltage references, and low drift active then ∆CMRR = 1.5µV/V or 116.5dB. filters are some of the circuits requiring matching between Typical performance of the instrumentation amplifier: two op amps. Input offset voltage = 25µV. The well-known triple op amp configuration illustrates Input bias current = 30pA. these concepts. Output offset is a function of the dif- Input resistance = 1012Ω. ference between the offsets of the two halves of the Input offset current = 30pA. LT1024. This error cancellation principle holds for a Input noise = 0.7µVP-P. considerable number of input-referred parameters in Power bandwidth (VO = ±10V) = 80kHz. addition to offset voltage and its drift with temperature. Clearly, the LT1024, by specifying and guaranteeing all of Input bias current will be the average of the two these matching parameters, can significantly improve the noninverting input currents (I + B ). The difference between performance of matching dependent circuits.
Three Op Amp Instrumentation Amplifier
15V R4 R6 4 14 100Ω 10k –INPUT + A 13 1% 1% 1/2 LT1024 3 R1 – 12 10k 1% –15V 15V R3 C1 2 7 2.1k 100pF – 1% R10 6 LT1037 OUTPUT 100k R8 3 200 + Ω 4 15V R2 –15V R5 10k 10 7 100Ω 1% GAIN = 1000 – 1% B 6 1/2 LT1024 R7 11 +INPUT + 9.76k 5 1% –15V R9 500Ω TRIM R8 FOR GAIN TRIM R9 FOR DC COMMON MODE REJECTION TRIM R10 FOR AC COMMON MODE REJECTION LT1024 • AI01 1024fa 7
