Terminology » LTCC Filter : Types,Selection,Benefits & Manufacturers

LTCC Filter : Types,Selection,Benefits & Manufacturers

Introduction : For highly integrated RF designs, LTCC (Low Temperature Co-Fired Ceramic) filters are a game changer. These multilayer ceramic filters embed inductors, capacitors and resistors within compact, surface mountable packages.

What is LTCC Filter?

It is a high frequency filter fabricated using a low temperature co-fired ceramic process. This method involves stacking multiple ceramic layers with dielectric and conductor materials like copper or silver. They are fired together at about 900 degreeC which enables integration of passive elements viz. capacitors, inductors, resistors within a compact multilayer ceramic package.

Types of LTCC filter

Following are various types of LTCC filters.

Low pass, High pass and Band Pass
Differential filters : It offers excellent common mode rejection and matched phase/gain. This configuration type is vital for balanced systems such as mixers or ADC front ends.
Balun bandpass filters : Combines balun transformer and band pass filter in one LTCC module.
Substrate Integrated Waveguide (SIW) filters : Useful for high selectivity narrowband filtering

Selection Guide

Following parameters are considered for selecting LTCC filter.

Insertion Loss and Return Loss
Frequency Range & Bandwidth
Impedance Matching
Stop Band Rejection
Power handling capacity
Package size/Footprint

LTCC BPF

The figure depicts LTCC band pass filter (BPF) designed for mmwave (millimeter wave) frequency band.

Advantages of LTCC filter

Following are some of the benefits of LTCC filter.

It offers high component density and miniaturization
It offers low insertion loss, high selectivity and built-in shielding
It offers rugged and repeatable performance which is ideal for high volume and harsh environment use.
It supports higher frequency with small footprints especially used in mmwave designs

Popular LTCC filter manufacturers

Manufacturers	Description with part nos.
Mini-Circuits	Example : LTCC Low pass filter, DC - 12900 MHz, 50 Ohm
Taoglas	Example : LLP.5875.Y.A.30, LTCC LPF for 5875 MHz
Johanson Technology	Offers miniature LPF with LTCC technology ideal for wifi, IoT and bluetooth applications requiring low insertion loss and high stop band rejection.
TDK Corporation	Available in 628.5 MHz to 9.8 GHz frequency range for various applications including wifi, zigbee, bluetooth, gsm, UMTS etc. range
Murata Manufacturing Co. Ltd.	Offers two layout types viz. LGA pin layout and CQT pin layout

Conclusion: LTCC filters offer an excellent balance of performance, miniaturization, and ruggedness. While upfront customization and layout sensitivity add complexity; the long term benefits in size, performance and manufacturability make them a leading choice for scalable RF design. These filters are preferable for crowded RF front ends and high frequency circuits.