Highpass RF Filters

Spectrum Control's database of low-loss highpass filter designs, with insertion loss as low as 0.1 dB, helps eliminate the need for additional gain when size, weight, and power (SWaP) initiatives are in place. These highpass filters suppress unwanted low-frequency interference, DC content, and subharmonic signals at the receiver front end while passing the desired higher-frequency spectrum. A flat passband response helps preserve pulse and chirp fidelity without introducing unwanted amplitude distortion. Spectrum Control optimizes pole and transmission-zero placement to achieve a sharp cutoff, strong rejection below the cutoff frequency, and low insertion loss in a compact design. This low-loss signal path helps maintain receiver sensitivity and signal-to-noise ratio (SNR) without harmful bit-error-rate (BER) degradation. Rapid Filter options are also available with Chebyshev and elliptic responses for critical delivery requirements.

Spectrum Control's highpass filter advantages

 Wide variety of highpass filter topologies: lumped, suspended substrate, and glass.

 Creative layouts minimize highpass filter footprint.

 Integral shielding improves isolation.

 Strategic pole and transmission-zero placement maximizes low-frequency rejection.

 Topology blending maximizes rejection while minimizing passband loss.

 Highpass filters can be machined from lightweight alloys to reduce weight.

Key Performance

Lumped Element Highpass Designs

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

Suspended Substrate Designs

Spectrum Control's suspended-substrate highpass filters combine lumped and distributed elements within a single package to achieve complex responses that neither approach could provide alone. This mixed-topology construction maintains low passband insertion loss, while gold vias improve isolation between filter sections. A Cauer response with strategically placed transmission zeros sharpens the cutoff and strengthens rejection below the cutoff frequency without increasing package size. Integrated cleanup stages extend low-frequency suppression, creating a compact filter capable of meeting demanding specifications that might otherwise require multiple components.

Glass RF Filters

Spectrum Control's ultra-miniature glass highpass 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 low-frequency signals below the cutoff. Passband group delay remains stable, as tight as 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.