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.