LT1793 Low Noise, Picoampere Bias Current, JFET Input Op Amp UFEATURESDESCRIPTIO ■ Input Bias Current, Warmed Up: 10pA Max The LT®1793 achieves a new standard of excellence in ■ 100% Tested Low Voltage Noise: 8nV/ √ Hz Max noise performance for a JFET op amp. For the first time low ■ A Grade 100% Temperature Tested voltage noise (6nV/√Hz) is simultaneously offered with ■ Offset Voltage Over Temp: 1mV Max extremely low current noise (0.8fA/√Hz), providing the ■ Input Resistance: 1013Ω lowest total noise for high impedance transducer applica- ■ Very Low Input Capacitance: 1.5pF tions. Unlike most JFET op amps, the very low input bias ■ Voltage Gain: 1 Million Min current (3pA typ) is maintained over the entire common ■ Gain-Bandwidth Product: 4.2MHz Typ mode range which results in an extremely high input resis- ■ Guaranteed Specifications with ±5V Supplies tance (1013Ω). When combined with a very low input ca- pacitance (1.5pF) an extremely high input impedance U results, making the LT1793 the first choice for amplifying APPLICATIO S low level signals from high impedance transducers. The ■ low input capacitance also assures high gain linearity when Photocurrent Amplifiers ■ buffering AC signals from high impedance transducers. Hydrophone Amplifiers ■ High Sensitivity Piezoelectric Accelerometers The LT1793 is unconditionally stable for gains of 1 or more, ■ Low Voltage and Current Noise Instrumentation even with 1000pF capacitive loads. Other key features are Amplifier Front Ends 250µV VOS and a voltage gain over 4 million. Each indi- ■ Two and Three Op Amp Instrumentation Amplifiers vidual amplifier is 100% tested for voltage noise, slew rate ■ Active Filters (3.4V/µs) and gain-bandwidth product (4.2MHz). , LTC and LT are registered trademarks of Linear Technology Corporation. Specifications at ±5V supply operation are also provided. For an even lower voltage noise please see the LT1792 data sheet. UTYPICAL APPLICATIOLow Noise Light Sensor with DC Servo C1 1kHz Output Voltage Noise 2pF Density vs Source Resistance 10k √Hz) V + R1 – 1M 2 – 7 VN 1k + 6 LT1793 VOUT RSOURCE D2 3 + C2 0.022µF 1N914 4 100 V – V + R2 CD D1 – 100k R3 1N914 10 V 1k N 2N3904 LT1097 SOURCE TA = 25°C + RESISTANCE VS = ±15V HAMAMATSU R5 R4 ONLY TOTAL 1kHz VOLTAGE NOISE DENSITY (nV/ 1 S1336-5BK 10k 1k 100 1k 10k 100k 1M 10M 100M 1G 1793 TA01 (908) 231-0960 R2C2 > C1R1 V – SOURCE RESISTANCE (Ω) CD = PARASITIC PHOTODIODE CAPACITANCE V – V V 2 OUT = 100mV/µWATT FOR 200nm WAVE LENGTH N = √(VOP AMP)2 + 4kTRS + 2qIBRS 330mV/µWATT FOR 633nm WAVE LENGTH 1793 TA02 1
