VHF-Band LC Bandpass Filter

Our Range of VHF-Band LC Bandpass Filter

Our range of VHF-Band bandpass filters are mostly LC filters. The VHF-Band, which covers from 30MHz to 300MHz, is very well suited to LC filter technologies for a given size and cost. Cavity filters at this frequency would be very huge and therefore costly. Although VHF SAW filters are widely available, they tend to have high passband insertion loss. It is typical to have insertion loss in the range of 15-30 dB for VHF SAW filters. Ceramic filters are available, but these tend to be customized.

One of our popular VHF-Band LC bandpass filter is ABPF-100MBW20M-01.

ABPF-100MBW20M-01 : 100 MHz Bandpass filter

ABPF-100MBW20M-01 is a VHF Band bandpass filter with a center frequency of 100MHz.  It has a 1-dB bandwidth of 20 MHz. The passband is from 90 MHz to 110MHz. The passband ripple is less than 0.6 dB and, according to the datasheets,  it has a maximum passband insertion loss of 2 dB. In reality, measured data shows that the insertion loss is less than 1 dB.

Applications of 100MHz Band Pass Filter

ABPF-100MBW20M-01 was initially designed as harmonic rejection filter for the 100MHz OXCO clock that are used in synthesizers. It is able to reject second and third harmonics of 100MHz by at least 60dBc.

Customers have also used this filter for the IF (Intermediate Frequency) filter in down-converters.

The pertinent parameters of ABPF-100MBW20M-01 are as listed in the table below:

ABPF-100MBW20M-01 100MHZ Band Pass Filter
Part NumberABPF-100MBW20M-01
Center Frequency100 MHz
Passband Frequency Range90MHz – 110MHz
Passband Bandwidth20 MHz
Passband Insertion Loss2 dB max
Rejection> 60dBc @ 200MHz, 300MHz

Other VHF-Band LC Filters

We have a number of VHF-Band LC Bandpass Filters. These include:

  • 50 MHz Band Pass Filter
  • 60 MHz Band Pass Filter
  • 70 MHz Band Pass Filter
  • 90 MHz Band Pass Filter
  • 100MHz Band Pass Filter
  • 144 MHz Band Pass Filter
  • 175 MHz Band Pass Filter
  • 200 MHZ Band Pass Filter
  • 235 MHz Band Pass Filter
  • and many more

Our VHF-Band LC filters include narrowband filters to wideband filters. Contact us for a full  listing of our VHF LC bandpass filter. Alternatively, contact us to get a custom LC filter designed to your specifications.

VHF-Band LC Bandpass Filter : Lumped Element and Band Pass Filters: The Basics

Band pass filters often use LC filters, or lumped element filters, and these filters are usually helpful in some RF designs. Not only are the resulting filters tighten, but they have zero “natural” re-entrant modes that one may encounter with other filtering technologies.

In every resonator of a HF, UHF or a VHF Band LC Filter, one may see both an inductor and a capacitor. In the series aspect, the L-C is fused in the series. Meanwhile in the shunt elements, the LC is fused in the parallel. If installation of such should fail, it can generate a band-stop filter instead of a band pass filter.

More on Lumped Element Filters

Lumped elements, like inductors, capacitors and resistors, are the most commonly used and crucial component in RF and microwave circuits. In order to design RF circuits correctly and effectively, knowledge about lumped elements is necessary.

However, lumped elements can’t always be integrated in high frequency applications due to characteristic variation. Plus, lumped elements are not the center of every RF circuits. However, they make up the basic block of a big module.

Band Pass Filter Basics

A band pass filter is classed as a second-order type of filter due to it having two reactive components within its design, the capacitors. It’s made up of two LC filter circuits that were classified as first-order filters.

When filters are being cascaded with one another, the resulting circuit will be now classified as an “nth-order” filter. The “n” stands for the individual reactive component numbers and so the poles within the filter’s design. Filters can be, for example, a 2nd-order, 4th-order and so on.

The higher the filters order the more elevated the slope will be at n times -20dB/decade. However, one capacitor value may be fused together two or more individual capacitors still stands as a single capacitor.

VHF-Band: Band Pass Filters Applications

A simple utilization of these filters is in audio amplifier applications or circuits just like in loudspeaker crossover filters or pre-amplifier tone controls. Oftentimes, it’s essential to only let a specific range of frequencies that don’t start off at 0Hz (DC) or end at some upper high frequency point, but are inside a specific scope or frequency band, either narrow or wide.

Another use for the band pass filters are in wireless transmitters and receivers. The main function of such this filter inside a transmitter is to limit the bandwidth of the output signal to the minimum and is essential to convey information at the desired speed in the desired form.

In a receiver, a band pass filter permits signals within a selected frequency range to be heard or decoded, while preventing unwanted frequency signals from passing through. Also, band pass filters are known to optimize the signal-to-noise ratio (A.K.A the sensitivity) of a receiver.

In both applications, a well-designed and well-integrated LC band pass filter (it can be HF, UHF or a VHF Band LC Filter), having optimum bandwidth for the mode and speed of communication being utilized, maximize the number of signals being transferred. At the same time, it minimizes the interference or competition happening among signals.

Click here to get a custom design filter with your specifications.