Datasheet LT1113 (Analog Devices) - 9

LT1113
Typical perForMance characTerisTics THD and Noise vs Output THD and Noise vs Output CCIF IMD Test (Equal Amplitude Amplitude for Noninverting Gain Amplitude for Inverting Gain Tones at 13kHz, 14kHz)*
1 1 0.1 ZL = 2k||15pF, fO = 1kHz Z V A L = 2k||15pF, fO = 1kHz S = ±15V V = +1, +10, +100 A R MEASUREMENT BANDWIDTH V = –1, –10, –100 L = 2k MEASUREMENT BANDWIDTH TA = 25°C 0.1 = 10Hz TO 22kHz 0.1 = 10Hz TO 22kHz 0.01 AV = 100 0.01 0.01 AV = –100 AV = ±10 AV = –10 AV = 10 0.001 0.001 A 0.001 V = 1 AV = –1 NOISE FLOOR NOISE FLOOR TOTAL HARMONIC DISTORTION + NOISE (%) TOTAL HARMONIC DISTORTION + NOISE (%) 0.0001 0.0001 INTERMODULATION DISTORTION (AT 1kHz)(%) 0.0001 0.3 1 10 30 0.3 1 10 30 20m 0.1 1 10 30 OUTPUT SWING (VP-P) OUTPUT SWING (VP-P) OUTPUT SWING (VP-P) 1113 • G25 1113 • G26 1113 • G27
applicaTions inForMaTion
The LT1113 dual in the plastic and ceramic DIP packages impedance increases due to higher current noise. The low are pin compatible with and directly replace such JFET op voltage noise of the LT1113 allows it to surpass every amps as the OPA2111 and OPA2604 with improved noise dual and most single JFET op amps available. For the best performance. Being the lowest noise dual JFET op amp performance versus area available anywhere, the LT1113 available to date, the LT1113 can replace many bipolar op is offered in the narrow SO-8 surface mount package with amps that are used in amplifying low level signals from standard pinout and no degradation in performance. high impedance transducers. The best bipolar op amps The low voltage and current noise offered by the LT1113 will eventually loose out to the LT1113 when transducer makes it useful in a wide range of applications, especially where high impedance, capacitive transducers are used 1k LT1124* such as hydrophones, precision accelerometers and photo C LT1113* diodes. The total output noise in such a system is the gain √Hz) S RS times the RMS sum of the op amp input referred voltage 100 – SOURCE RESISTANCE = 2R + LT1124† noise, the thermal noise of the transducer S = R , and the op VO * PLUS RESISTOR † R C PLUS RESISTOR | | 1000pF CAPACITOR S S amp bias current noise times the transducer impedance. Vn = AV √Vn2 Figure 1 shows total input voltage noise versus sour (OP AMP) + 4kTR + 2q IB • R2 ce 10 LT1113† resistance. In a low source resistance (<5k) application LT1113 INPUT NOISE VOLTAGE (nV the op amp voltage noise will dominate the total noise. 1k LT1124 LT1124* This means the LT1113 will beat out any dual JFET op RESISTOR NOISE ONLY 1 amp, only the lowest noise bipolar op amps have the edge 100 1k 10k 100k 1M 10M 100M C LT1113* √Hz) S SOURCE RESISTANCE (Ω) R (at low source resistances 1113 • F01 ). As the source resistance S 100 – SOURCE RESISTANCE = 2R + S = R increases from 5k to 50k, the LT1113 will match the best V LT1124† O * PLUS RESISTOR † R C PLUS RESISTOR | | 1000pF CAPACITOR bipolar op amps for noise performance, since the thermal S S Vn = AV √Vn2(OP AMP) + 4kTR + 2q IB • R2 noise of the transducer (4kTR) begins to dominate the 10 LT1113† total noise. A further increase in source resistance, above
Figure 1. Comparison of LT1113 and LT1124 Total
LT1113 50k, is where the op amp’s current noise component INPUT NOISE VOLTAGE (nV
Output 1kHz Voltage Noise Versus Source Resistance
LT1124 RESISTOR NOISE ONLY 1113fc 1100 1k 10k 100k 1M 10M 100M SOURCE RESISTANCE (Ω) 1113 • F01 For more information www.linear.com/LT1113 9