LM13600 Dual Operational Transconductance Amplifier

Overview

The LM13600 is a dual operational transconductance amplifier (OTA) that provides excellent performance in applications requiring voltage-controlled amplification or filtering. This integrated circuit contains two independent, current-controlled transconductance amplifiers with differential inputs and push-pull outputs. The device is particularly notable for its linearizing diodes at the inputs, which significantly reduce distortion and improve signal-to-noise ratio.

Designed for precision analog applications, the LM13600 offers a wide transconductance adjustment range spanning six decades, making it exceptionally versatile for various analog signal processing tasks. The shared power supply configuration while maintaining independent operation makes this component ideal for stereo applications or any design requiring multiple, matched OTAs.

Key Features

• Dual matched operational transconductance amplifiers in single package
• Linearizing diodes for reduced distortion and improved input levels
• 10 dB signal-to-noise improvement at 0.5% THD
• Transconductance (gm) adjustable over six decades
• Differential voltage inputs with high impedance
• Push-pull output buffers with controlled impedance
• Wide power supply range: ±4V to ±18V
• Excellent temperature stability
• Matched amplifier characteristics for stereo applications
• Buffers optimized for dynamic range complementation

Applications

The LM13600 finds use in numerous analog signal processing applications, particularly where voltage control is required:

Audio Processing

• Voltage-controlled amplifiers (VCAs)
• Voltage-controlled filters (VCFs)
• Dynamic range compressors/expanders
• Analog synthesizer modules
• Automatic gain control circuits

Instrumentation and Control

• Precision current-controlled circuits
• Analog multipliers
• Sample-and-hold circuits
• Waveform generators
• Modulators/demodulators

Communications Systems

• Variable bandwidth filters
• AGC amplifiers
• Signal processing modules
• Frequency mixers

Electrical Characteristics

The following specifications are typical at ±15V power supply and TA = 25°C unless otherwise noted:

Amplifier Section

• Transconductance range: 0 to 2.6 mS (typical)
• Transconductance adjustment range: 6 decades
• Input bias current: 500 nA (maximum)
• Input offset current: 100 nA (maximum)
• Input offset voltage: 2 mV (maximum)
• Common mode rejection ratio: 110 dB (typical)
• Power supply rejection ratio: 100 dB (typical)

Buffer Section

• Output current: ±20 mA (maximum)
• Output resistance: 30 Ω (typical)
• Bandwidth: 2 MHz (typical)
• Slew rate: 50 V/μs (typical)

General Characteristics

• Power supply range: ±4V to ±18V
• Quiescent current: 2 mA per amplifier (typical)
• Operating temperature range: 0°C to +70°C
• Total harmonic distortion: 0.5% (typical at 1 kHz)
• Signal-to-noise ratio: 10 dB improvement over standard OTAs

Package Information

The LM13600 is available in multiple package options to suit different application requirements:

16-Pin Plastic DIP (N Package)

• Package dimensions: 19.3mm x 6.35mm
• Lead pitch: 2.54mm
• Operating temperature: 0°C to +70°C
• Moisture sensitivity level (MSL): 1

16-Pin SOIC (D Package)

• Package dimensions: 9.9mm x 3.9mm
• Lead pitch: 1.27mm
• Operating temperature: 0°C to +70°C
• Moisture sensitivity level (MSL): 1

Thermal Characteristics

• Thermal resistance, θJA (DIP): 80°C/W
• Thermal resistance, θJA (SOIC): 160°C/W
• Maximum junction temperature: 150°C

Design Considerations

When implementing the LM13600 in circuit designs, several important factors should be considered:

Power Supply Decoupling

Proper power supply decoupling is essential for optimal performance. A 0.1μF ceramic capacitor should be placed as close as possible to each power supply pin, with larger electrolytic capacitors (10μF or greater) used for bulk decoupling.

Input Protection

While the built-in linearizing diodes provide some protection, input signals should be limited to within the supply voltage range. For applications where input signals may exceed these limits, external clamping diodes or current-limiting resistors may be required.

Thermal Management

In high-current applications or when operating at elevated ambient temperatures, thermal considerations become important. The SOIC package has approximately double the thermal resistance of the DIP package, which may necessitate reduced power dissipation or improved airflow in compact designs.

PCB Layout

Careful PCB layout is recommended, particularly for high-frequency applications. Keep input traces short and well-shielded from output traces to prevent oscillation. The high-impedance inputs should be guarded from potential noise sources.

Conclusion

The LM13600 dual operational transconductance amplifier offers exceptional performance and flexibility for a wide range of analog signal processing applications. Its combination of matched amplifiers, linearizing diodes, and wide transconductance adjustment range make it particularly valuable in audio processing, instrumentation, and communication systems. The availability in both through-hole and surface-mount packages ensures compatibility with various manufacturing processes and design requirements.

When properly implemented with attention to power supply decoupling, thermal management, and PCB layout considerations, the LM13600 can provide reliable, high-performance operation in demanding analog circuit applications.