1 Features
1• Advantages
– Replace Expensive Hybrid and Module FET
Op Amps
– Rugged JFETs Allow Blow-Out Free Handling
Compared With MOSFET Input Devices
– Excellent for Low Noise Applications Using
Either High or Low Source Impedance—Very
Low 1/f Corner
– Offset Adjust Does Not Degrade Drift or
Common-Mode Rejection as in Most
Monolithic Amplifiers
– New Output Stage Allows Use of Large
Capacitive Loads (5,000 pF) Without Stability
Problems
– Internal Compensation and Large Differential
Input Voltage Capability
• Common Features
– Low Input Bias Current: 30 pA
– Low Input Offset Current: 3 pA
– High Input Impedance: 1012 Ω
– Low Input Noise Current: 0.01 pA/√Hz
– High Common-Mode Rejection Ratio: 100 dB
– Large DC Voltage Gain: 106 dB
• Uncommon Features
– Extremely Fast Settling Time to 0.01%:
– 4 μs for the LFx55 devices
– 1.5 μs for the LFx56
– 1.5 μs for the LFx57 (AV = 5)
– Fast Slew Rate:
– 5 V/μs for the LFx55
– 12 V/μs for the LFx56
– 50 V/μs for the LFx57 (AV = 5)
– Wide Gain Bandwidth:
– 2.5 MHz for the LFx55 devices
– 5 MHz for the LFx56
– 20 MHz for the LFx57 (AV = 5)
– Low Input Noise Voltage:
– 20 nV/√Hz for the LFx55
– 12 nV/√Hz for the LFx56
– 12 nV/√Hz for the LFx57 (AV = 5)

2 Applications
• Precision High-Speed Integrators
• Fast D/A and A/D Converters
• High Impedance Buffers
• Wideband, Low Noise, Low Drift Amplifiers
• Logarithmic Amplifiers
• Photocell Amplifiers
• Sample and Hold Circuits

3 Description
The LFx5x devices are the first monolithic JFET input
operational amplifiers to incorporate well-matched,
high-voltage JFETs on the same chip with standard
bipolar transistors (BI-FET™ Technology). These
amplifiers feature low input bias and offset
currents/low offset voltage and offset voltage drift,
coupled with offset adjust, which does not degrade drift or common-mode rejection. The devices are also
designed for high slew rate, wide bandwidth,
extremely fast settling time, low voltage and current
noise and a low 1/f noise corner.