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Lowpass Filters

Low-insertion-loss lowpass filters (0.1 dB) are essential for many of today’s defense platforms and modern wireless environments that require high spectral fidelity. Spectrum Control’s low-insertion-loss lowpass filters help receivers detect and process low-power targets, as well as discern targets of interest in interference-heavy environments. Spectrum Control offers lowpass filters with 0.1 dB loss to help identify weak communication transmissions and recognize valuable intelligence signals in a crowded spectrum.

Visit Spectrum Control's Lowpass Filter Customization Tool today to optimize your demanding lowpass filter requirements.

Spectrum Control’s database of low-loss lowpass filter designs, with insertion loss as low as 0.1 dB, helps eliminate the need for additional gain in size, weight, and power (SWaP)-constrained systems. Spectrum Control’s low-loss lowpass filters also suppress harmonics at the receiver front end, helping maintain a flat amplitude response and prevent distortion and unwanted spurious modulation.

Spectrum Control’s low-loss lowpass filter designs optimize pole placement to achieve high rejection in a compact package. These filters help maintain receiver sensitivity in crowded wireless spectra while reducing heat, cooling requirements, and package weight.

Low-loss lowpass filters also improve signal-to-noise ratio (SNR) and maintain spectral purity without degrading bit error rate (BER). Spectrum Control offers Rapid Filter options with Chebyshev and elliptic responses to meet critical demand requirements.

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Spectrum Control Lowpass Filter Advantages

check mark.png  Wide variety of lowpass filter topologies, including lumped, cavity, SAW, and glass

check mark.png Creative layouts that minimize the lowpass filter footprint

check mark.png Integral shielding that improves isolation

check mark.png Strategic pole placement that maximizes rejection

check mark.png Topology blending to maximize rejection and minimize loss

check mark.png Lowpass cavity filters machined from lightweight alloys to reduce weight

Key Performance

 
Feature
 Specification
Frequency
 100 kHz to 40 GHz
Size
 As small as 3 mm
Temp Drift
 1 ppm/°C
Power Handling
 400 Watts CW max.
Insertion Loss
 As low as 0.1 dB

 

How Lowpass Filters Work

Lumped element lowpass designs

Built from carefully selected discrete inductors and capacitors, these lowpass lumped element filters operate from 1 kHz to 3 GHz. Component values and performance characteristics are optimized to achieve the desired cutoff frequency, low insertion loss, and strong rejection of unwanted high-frequency signals. Because the components are much smaller than the operating wavelength, lumped element designs also provide a compact footprint and can be readily customized for specific electrical and packaging requirements.

Suspended substrate designs

Spectrum Control’s suspended-substrate lowpass filters combine lumped and distributed elements in one package to achieve responses neither approach provides alone. This mixed-topology construction maintains low insertion loss, while gold vias improve isolation. A Cauer response with strategic transmission zeros sharpens cutoff and strengthens stopband rejection without added size. Integrated cleanup stages extend high-frequency suppression, creating a compact filter that meets demanding specifications otherwise requiring multiple components.

Glass RF filters

Spectrum Control’s ultra-miniature glass lowpass filters deliver high-Q performance in one of the smallest packages available, with operation up to 10 GHz and insertion loss below 2 dB in many designs. Their high-Q construction provides up to 70 dB of stopband rejection, effectively suppressing unwanted high-frequency signals despite the compact footprint. Passband group delay remains stable within 1 ns across temperature, making these filters ideal for phase-sensitive applications. Each design handles up to 1 watt of input power and can be customized for specific cutoff frequency, rejection, or packaging requirements.

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How Lowpass Topologies Compare to One Another

check mark.png  Lumped Element: Discrete inductors and capacitors provide a compact, economical solution from 1 kHz to 3 GHz, with excellent flexibility for customizing cutoff frequency and rejection.

check mark.png  3D Glass SMT: High-Q glass-substrate integration provides low insertion loss, precise cutoff characteristics, and strong stopband rejection in an ultraminiature package for applications up to 10 GHz.

Applications

Defense and Radar Systems

  • Suppression of harmonics and unwanted high frequency signals
  • Low insertion loss within the operating passband
  • Stable performance under thermal cycling and vibrationl

High Power Wireless Infrastructure

  • Harmonic and spurious-signal suppression in base stations and repeaters
  • High power handling with minimal passband loss
  • Strong stopband rejection above the desired cutoff frequency

Available Across Filter Functions

Lowpass filtering is available across Spectrum Control’s portfolio of frequency selective components, providing a range of technologies to meet different frequency, power, rejection, and packaging requirements:

  • Cavity Filters: High-power lowpass solutions provide low insertion loss, sharp cutoff characteristics, and strong stopband rejection.
  • Notch Filters: Suppress a specific interfering frequency while leaving the surrounding passband largely unaffected.
  • Diplexers: Use lowpass and highpass filter paths to split or combine two frequency bands within one compact assembly.
  • Triplexers: Combine three filtered paths while maintaining low insertion loss and high isolation between bands.
  • Multiplexers: Integrate multiple lowpass, highpass, or bandpass sections to channelize four or more frequency bands in complex systems.

Ready to spec a lowpass filter for your application? Try our Filter Customization Tool.