The LSK489

Linear Systems has introduced the LSK489, a monolithic dual N-Channel JFET engineered to deliver exceptional performance in both audio and instrumentation applications. This component stands out due to its ultra-low noise characteristics, with a typical noise density of 1.8 nV/√Hz at 1 kHz, ensuring minimal signal interference in sensitive analog circuits.

A notable feature of the LSK489 is its remarkably low input capacitance of 4 pF, significantly lower than comparable JFETs, which often exhibit capacitances around 25 pF. This reduced capacitance minimizes intermodulation distortion and allows for simpler circuit designs without the need for complex cascode configurations that can introduce additional noise.

The device's design includes interleaved JFETs on the same silicon die, providing excellent matching and thermal tracking between the two channels. This construction ensures consistent performance across varying temperatures and

operating conditions, making it ideal for precision applications.

The LSK489 is available in multiple package options to accommodate diverse design requirements:

• TO-71 6L: A through-hole metal can package offering robust performance.

• SOIC 8L: A surface-mount option facilitating compact designs.

• SOT-23 6L: A smaller surface-mount package suitable for space-constrained applications.

All versions are RoHS-compliant, aligning with environmental and safety standards.

In terms of electrical characteristics, the LSK489 offers a gate-to-source cutoff voltage ranging from -1.5 V to -3.5 V and a drain-to-source saturation current (IDSS) between 2.5 mA and 15 mA, depending on the grade. These specifications provide designers with flexibility in biasing and application suitability.

The LSK489 is particularly well-suited for applications requiring high input impedance and low noise, such as:

• Microphone Preamplifiers: Enhancing audio signal fidelity.

• Phono Preamplifiers: Improving the quality of vinyl record playback.

• Instrumentation Amplifiers: Ensuring precise measurements in scientific equipment.

• Acoustic Sensors: Capturing accurate sound measurements in various environments.