Beyond Low Noise: Why Input Capacitance Matters
- JC - Linear Systems
- 6 days ago
- 1 min read
Last week we discussed why engineers continue to choose discrete JFETs for precision analog designs. But selecting the right JFET involves more than comparing noise specifications.
For high-impedance applications such as photodiodes, hydrophones, piezoelectric sensors, condenser microphones, and precision instrumentation, input capacitance can have a significant impact on circuit performance.
Higher input capacitance can reduce bandwidth, increase signal loading, and make compensation more challenging. That's why many engineers evaluate both ultra-low noise and low input capacitance when selecting an input device.
The LSK489Â was designed with this balance in mind, combining:
Ultra-low noise (1.8 nV/√Hz typical)
Typical 4 pF input capacitance
Excellent monolithic matching
Multiple package options, including bare die
The result is a device well suited for demanding analog front ends where preserving weak signals is critical.
Over the coming months, we'll continue sharing practical engineering insights like this as part of the new Linear Systems Learning Series, exploring the concepts behind precision analog design—not just the products.
What analog design topic would you like us to cover next?