BAW & SAW Filters
Michel Chomiki 1
06/01/2006B A W & S A W F i l t e r s
Bulk Acoustic Waves (Crystal) Filters
Surface Acoustic Waves Filters
B A W & S A W F i l t e r s
2
General presentation of BAW & SAW filters
BAW filters ?Quartz
?Lithium Tantalate ?Langasite
SAW filters ?FIR
?Low loss
BAW vs SAW high selectivity filters
Temperature insensitive IF SAW filters
? A powerful technique to compensate thermal drift of SAW
IF filters
B A W & S A W F i l t e r s
3
General
presentation BAW filters SAW filters BAW vs SAW
Temperature insensitive IF SAW filters
General presentation
B A W & S A W F i l t e r s
4
Band Pass Filters
Frequency range : 5 MHz to 2.5 GHz Fractional bandwidth : 10-4to 0.5
Shape factor : 1.05 (3dB/30dB) or 1.2 (3dB/60dB) min. Insertion loss : 1 dB min. (low loss filters) Out-of-band rejection : 100 dB max.
Operating temperature range : -40 °C to + 85 °C
Notch Crystal Filters
B A W & S A W F i l t e r s
5
B A W & S A W F i l t e r s
6
Bulk & Surface Acoustic Waves technologies Piezoelectric substrates
?Quartz, Lithium Niobate, Lithium Tantalate, Langasite
BAW & SAW die packaging ?Metallic or ceramic ?Hermetically sealed ?SMD or plug-in
SAW filters are monolithic
BAW filters are sub-assembly of Crystal resonators and high Q passive discrete (capacitor, coil, etc)
B A W & S A W F i l t e r s
7
Request for quotation
?BAW : Complete design achievable in 1 week ?SAW : Preliminary design achievable in 1 week
Complete design achievable in 3 to 4 weeks
?Including tolerance sensitivity study
?
Measurements fit simulation in more than 90 % of cases.
Prototypes delivery : ?BAW :12 weeks ?SAW : 6 to 8 weeks
?Plug and play, technical report, preliminary specification ?
Technical support to implement the filter on customers’
PCB if necessary
B A W & S A W F i l t e r s
8
General
presentation BAW filters SAW filters BAW vs SAW
Temperature insensitive IF SAW filters
BAW filters
B A W & S A W F i l t e r s
9
High selectivity & Linear phase band pass filters
?Butterworth, Chebyshev, Cauer, Bessel, Gaussian, … Amplitude & phase matching filters
Notch filters
Band-pass :
10 –80 MHz @ 3 dB IL = 3 dB
Notch :
Fc = 50 MHz
BW > 40 kHz @ 40 dB
20 kHz/div
10 dB/div
B A W & S A W F i l t e r s
10
Piezoelectric substrate
?Quartz, Lithium Tantalate,Langasite
One or two resonators (monolithic cell) per die Size (mm) : 20 x 10 x 10 to 60 x 30 x 20
SMD or plug-in
B A W & S A W F i l t e r s
11
High selectivity & Linear phase Up to 12 poles
6 dBm max. input power
Fc = 243 MHz B/Fc = 0.02 %IL = 7 dB
10 dB/div
30 kHz/div
B A W & S A W F i l t e r s
12
Parameter Unit Minimum
Maximum Center frequency MHz 5 300 Relative bandwidth % 0.01 0.4 / 0.2
Insertion loss dB 1 6 Out of band rejection dB 20 100 / 80
3 dB / 60 dB shape factor - 1.2 / 6
Nota : High selectivity / Linear phase
B A W & S A W F i l t e r s
13
! "
High selectivity & Linear phase 2 to 8 poles
10 dBm max. input power
Fc = 10.7 MHz B/Fc = 0.3 %IL = 5 dB
Flat group delay
1 dB/div
2 μs/div
10 kHz/div
B A W & S A W F i l t e r s
14
! "
Parameter Unit Minimum
Maximum Center frequency MHz 10 120 Relative bandwidth % 0.4 5 / 2.5 Insertion loss dB 2 8 Out of band rejection dB 20 80 3 dB / 60 dB shape factorQ - 2 / 6
Nota : High selectivity / Linear phase
B A W & S A W F i l t e r s
15
! #
Lower cost than equivalent filter on Lithium Tantalate Smaller size (monolithic cells)
6 dBm max. input power
Fc = 10.7 MHz B/Fc = 0.65 %IL = 5 dB
20 x 10 x 10 mm
10 kHz/div 1 dB/div
0.1 MHz/div 10 dB/div
B A W & S A W F i l t e r s
16
! #
Parameter Unit Minimum
Maximum
Center frequency MHz 10 22 Relative bandwidth % 0.04 1 / 0.5 Insertion loss dB 2 8 Out of band rejection dB 20 80 3 dB / 60 dB shape factor - 1.5 / 6
Nota : High selectivity / Linear phase
B A W & S A W F i l t e r s
17
General
presentation BAW filters SAW filters BAW vs SAW
Temperature insensitive IF SAW filters
SAW filters
B A W & S A W F i l t e r s
18
Piezoelectric substrate
?Quartz, Lithium Niobate, Lithium Tantalate, Langasite High shape factor (FIR) & low loss (Resonator) filters Size (mm) : 3 x 3 x 0.7 to 25 x 75 x 6.5
Ceramic or metallic package
SMD or plug-in
B A W & S A W F i l t e r s
$
Design in time domain (Finite Impulse Response) Very high shape factor : down to 1.05
Moderate to high insertion loss : IF applications
B A W & S A W F i l t e r s
Parameter
Unit Minimum
Maximum Center frequency MHz 50 1500 Relative bandwidth % 0.3 50 Insertion loss
dB 5 40 Out of band rejection dB 40 70 3 dB / 30 dB shape factor
- 1.05
67697173
-70
-60
-50
-40
-30
-20
-10
Fc = 70 MHz B/Fc = 1.8 %IL = 22 dB 73 x 20 mm
540
570
600
-60
-50
-40
-30
-20
-10
Fc = 570 MHz B/Fc = 1.2 %IL = 12 dB 9.5 x 9.5 mm