LF156 - JFET Input Operational Amplifier

Overview

The LF156 is a monolithic JFET input operational amplifier that combines well-matched, high-voltage JFETs with standard bipolar transistors using BI-FET™ technology. This integration provides superior performance characteristics, making it suitable for high-precision applications. The LF156 is part of a family that includes the LF155A, LF156A, and LF157A, all designed to deliver low input bias and offset currents, low noise, and high-speed performance.

This operational amplifier is particularly noted for its high input impedance, low offset voltage drift, and excellent common-mode rejection ratio (CMRR). Its design ensures fast settling times, wide bandwidth, and high slew rates, making it ideal for applications requiring precision and speed.

Features

• Low Input Bias Current: 30 pA (typical)
• Low Input Offset Current: 3 pA (typical)
• High Input Impedance: 10¹² Ω (typical)
• Low Input Offset Voltage: 1 mV (typical)
• Low Input Offset Voltage Temperature Drift: 3 µV/°C (typical)
• Low Input Noise Current: 0.01 pA/√Hz (typical)
• High Common-Mode Rejection Ratio (CMRR): 100 dB (typical)
• Large DC Voltage Gain: 106 dB (typical)
• High Slew Rate: 12 V/µs (typical)
• Wide Bandwidth: 5 MHz (typical)
• Fast Settling Time: 1.5 µs to 0.1% (typical)

Applications

The LF156 is designed for use in a wide range of precision and high-speed applications, including:

• Instrumentation Amplifiers: Due to its low noise and high input impedance, the LF156 is ideal for sensitive measurement equipment.
• Active Filters: The high slew rate and wide bandwidth make it suitable for active filter designs.
• Data Acquisition Systems: Its fast settling time and precision are beneficial in analog-to-digital conversion circuits.
• Medical Electronics: The low input bias current and high CMRR are critical for medical instrumentation.
• Audio Processing: The low noise and high gain make it suitable for high-fidelity audio applications.
• Voltage Followers: The high input impedance and low offset voltage are advantageous in buffer applications.

Electrical Characteristics

The following table summarizes the key electrical characteristics of the LF156 operational amplifier under typical operating conditions (V_CC = ±15V, T_A = 25°C unless otherwise specified).

DC Characteristics

• Input Offset Voltage: 1 mV (max: 5 mV)
• Input Bias Current: 30 pA (max: 200 pA)
• Input Offset Current: 3 pA (max: 50 pA)
• Input Resistance: 10¹² Ω (min)
• Common-Mode Rejection Ratio (CMRR): 100 dB (min)
• Power Supply Rejection Ratio (PSRR): 90 dB (min)
• Large-Signal Voltage Gain: 106 dB (min)

AC Characteristics

• Slew Rate: 12 V/µs (min: 10 V/µs)
• Gain Bandwidth Product: 5 MHz (typical)
• Settling Time (to 0.1%): 1.5 µs (typical)
• Input Noise Voltage: 15 nV/√Hz (typical at 1 kHz)
• Input Noise Current: 0.01 pA/√Hz (typical at 1 kHz)

Power Supply Characteristics

• Supply Voltage Range: ±5V to ±18V
• Quiescent Current: 3.5 mA (typical)
• Power Consumption: 105 mW (typical at ±15V)

Package Information

The LF156 is available in multiple package options to suit various application requirements. The following packages are commonly available:

Standard Packages

• 8-Pin PDIP (Plastic Dual In-Line Package):
  • Dimensions: 9.81 mm x 6.35 mm
  • Pin spacing: 2.54 mm
  • Operating temperature range: -55°C to +125°C
• 8-Pin SOIC (Small Outline Integrated Circuit):
  • Dimensions: 4.90 mm x 3.91 mm
  • Pin spacing: 1.27 mm
  • Operating temperature range: -40°C to +85°C

Thermal Characteristics

• Junction-to-Ambient Thermal Resistance (θ_JA): 100°C/W (PDIP), 160°C/W (SOIC)
• Maximum Junction Temperature (T_J): 150°C
• Storage Temperature Range: -65°C to +150°C

Conclusion

The LF156 operational amplifier is a high-performance component that combines the benefits of JFET and bipolar technologies. Its low noise, high input impedance, and fast response make it an excellent choice for precision analog applications. Whether used in instrumentation, filtering, or data acquisition, the LF156 delivers reliable and consistent performance across a wide range of operating conditions.