Datasheet LT1793 (Analog Devices) - 7
| Hersteller | Analog Devices |
| Beschreibung | Low Noise, Picoampere Bias Current, JFET Input Op Amp |
| Seiten / Seite | 12 / 7 — TYPICAL PERFOR A CE CH. ARA TERISTICS. Short-Circuit Output Current. … |
| Dateiformat / Größe | PDF / 176 Kb |
| Dokumentensprache | Englisch |
TYPICAL PERFOR A CE CH. ARA TERISTICS. Short-Circuit Output Current. Input Bias and Offset Currents. vs Temperature
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LT1793
W U TYPICAL PERFOR A CE CH C ARA TERISTICS Short-Circuit Output Current Input Bias and Offset Currents vs Temperature Supply Current vs Temperature vs Chip Temperature
40 5 30n VS = ±15V V 10n S = ±15V VCM = –10 TO 13V 35 3n 1n 30 BIAS SINK SOURCE VS = ±15V 300p CURRENT 25 4 100p VS = ±5V 30p 20 10p OFFSET OUTPUT CURRENT (mA) CURRENT 3p 15 SUPPLY CURRENT PER AMPLIFIER (mA) INPUT BIAS AND OFFSET CURRENTS (A) 1p 10 3 0.3p – 75 – 50 – 25 0 25 50 75 100 125 – 75 – 50 – 25 0 25 50 75 100 125 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 1793 G19 1793 G20 1793 G21
O U U W U APPLICATI S I FOR ATIO LT1793 vs the Competition
The extremely high input impedance (1013Ω) assures that the input bias current is almost constant over the entire With improved noise performance, the LT1793 in the common mode range. Figure 1 shows how the LT1793 PDIP directly replaces such JFET op amps as the OPA111 stands up to the competition. Unlike the competition, as the and the AD645. The combination of low current and input voltage is swept across the entire common mode voltage noise of the LT1793 allows it to surpass most dual range the input bias current of the LT1793 hardly changes. and single JFET op amps. The LT1793 can replace many As a result the current noise does not degrade. This makes of the lowest noise bipolar amps that are used in amplify- the LT1793 the best choice in applications where an ing low level signals from high impedance transducers. amplifier has to buffer signals from a high impedance The best bipolar op amps (with higher current noise) will transducer. eventually lose out to the LT1793 when transducer im- pedance increases. Offset nulling will be compatible with these devices with the wiper of the potentiometer tied to the negative supply 100 (Figure 2a). No appreciable change in offset voltage drift CURRENT NOISE = √2qIB 80 60 15V 15V 40 OP215 20 2 – 7 2 – 7 LT1793 0 6 6 –20 3 + 4 3 + 4 AD822 5 5 –40 ∆V ∆V 1 OS = ±13mV 1 OS = ±1.3mV INPUT BIAS CURRENT (pA) –60 50k 10k 10k –80 –100 – 15V –15 –10 –5 0 5 10 15 50k COMMON MODE RANGE (V) – 15V 1793 F01 1793 F02
(a) (b) Figure 1. Comparison of LT1793, OP215, and AD822 Input Bias Current vs Common Mode Range Figure 2
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W U TYPICAL PERFOR A CE CH C ARA TERISTICS Short-Circuit Output Current Input Bias and Offset Currents vs Temperature Supply Current vs Temperature vs Chip Temperature
40 5 30n VS = ±15V V 10n S = ±15V VCM = –10 TO 13V 35 3n 1n 30 BIAS SINK SOURCE VS = ±15V 300p CURRENT 25 4 100p VS = ±5V 30p 20 10p OFFSET OUTPUT CURRENT (mA) CURRENT 3p 15 SUPPLY CURRENT PER AMPLIFIER (mA) INPUT BIAS AND OFFSET CURRENTS (A) 1p 10 3 0.3p – 75 – 50 – 25 0 25 50 75 100 125 – 75 – 50 – 25 0 25 50 75 100 125 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 1793 G19 1793 G20 1793 G21
O U U W U APPLICATI S I FOR ATIO LT1793 vs the Competition
The extremely high input impedance (1013Ω) assures that the input bias current is almost constant over the entire With improved noise performance, the LT1793 in the common mode range. Figure 1 shows how the LT1793 PDIP directly replaces such JFET op amps as the OPA111 stands up to the competition. Unlike the competition, as the and the AD645. The combination of low current and input voltage is swept across the entire common mode voltage noise of the LT1793 allows it to surpass most dual range the input bias current of the LT1793 hardly changes. and single JFET op amps. The LT1793 can replace many As a result the current noise does not degrade. This makes of the lowest noise bipolar amps that are used in amplify- the LT1793 the best choice in applications where an ing low level signals from high impedance transducers. amplifier has to buffer signals from a high impedance The best bipolar op amps (with higher current noise) will transducer. eventually lose out to the LT1793 when transducer im- pedance increases. Offset nulling will be compatible with these devices with the wiper of the potentiometer tied to the negative supply 100 (Figure 2a). No appreciable change in offset voltage drift CURRENT NOISE = √2qIB 80 60 15V 15V 40 OP215 20 2 – 7 2 – 7 LT1793 0 6 6 –20 3 + 4 3 + 4 AD822 5 5 –40 ∆V ∆V 1 OS = ±13mV 1 OS = ±1.3mV INPUT BIAS CURRENT (pA) –60 50k 10k 10k –80 –100 – 15V –15 –10 –5 0 5 10 15 50k COMMON MODE RANGE (V) – 15V 1793 F01 1793 F02
(a) (b) Figure 1. Comparison of LT1793, OP215, and AD822 Input Bias Current vs Common Mode Range Figure 2
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