Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Cavity and LTCC filters

senmeis

Full Member level 2
Joined
Nov 26, 2014
Messages
128
Helped
0
Reputation
0
Reaction score
0
Trophy points
16
Activity points
962
Hi,

can anybody clarify the main difference between cavity and LTCC filters in mmWave field? They both seem to have a high Q.
 

ktr

Full Member level 3
Joined
Jun 11, 2018
Messages
162
Helped
16
Reputation
32
Reaction score
16
Trophy points
18
Location
Turkey
Activity points
1,420
I believe LTCC is a surface mount unit while cavity filters are more like a wave-guide like structure. Integrating cavity filters into a PCB requires different mounting techniques while LTCC can be made as SMT and soldered like a classic component.
 

JohnBG

Junior Member level 3
Joined
Feb 23, 2021
Messages
27
Helped
4
Reputation
8
Reaction score
2
Trophy points
3
Activity points
238
1. The term cavity is a broad one: traditionally microwave filtering/resonant cavities are made of metal, containing just air, compressed air, or a gas, sometimes liquid, or a solid that may melt to absorb heat and thus solve heat management.

2. But a dielectric or diamagnetic piece of material is also a cavity that resonates (high Q) at certain frequencies while showing high insertion loss on most of the input frequency band, literature reference Microwave Engineering 4th ed. D.Pozar.

3. LTC or LTCC filters is the marketing denomination of some manufacturers for microstrip built, lump components, that may include operational amplifiers, building blocks tagged as filters.

4. One can build filters with capacitors and inductors (SMD, ..) or/and transmission lines only. Or you can combine LC and microstrip lines with small resonators placed nearby tracks, acting as capacitors, but with higher Q.

Have at the following selection guide

5. Cavity only filters have higher frequency selectivity, but they may also have an overall higher insertion loss, requiring pre-amplifier, and my generate more output signal power, but may also produce more noise and/or harmonics, requiring additional output stages.

6. Now most of UHF spectrum has been auctioned to mobile operators but there are still some UHF channels available for TV broadcast. The CATV head end shown in following link


is built with one UHF amplifier per UHF channel. Each amplifier has a cavity filter at the input and another at the output.


7. The Klystron shown here

has cavities filtering the electron beam, what Mr Dehn mentions as bringing the electrons to same velocity.

Hope it helps

JohnBG
jgb2012@sky.com
 

LaTeX Commands Quick-Menu:

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top