Transcript IWPC MB MM handsets Apr 2008

Optical Navigation Division
UMTS Multiband Architectures:
Handling Complexity in the RF Front End
William Mueller
Strategic Marketing Manager
Avago Technologies Wireless Semiconductor Division
18 April 2008
Wireless Semiconductor Division
Agenda
Definition of “Front End”
Architectural Progressions
Comparisons and Tradeoffs
Comments on Components
Wish List
Wireless Semiconductor Division
The “Front End”
Power Amplifiers
GaAs HBT
GaAs FET
Si MOSFET
Duplexers, Diplexers, Filters
acoustic (SAW, BAW, FBAR)
dielectric (ceramic, substrate)
Switches
FET (GaAs, SoS)
diode
mechanical
(MEMS)
Other
passives, substrate, …
Specialized Technologies Connecting the RFIC to the Antenna.
Avago Technologies (formerly HP Semiconductor, then Agilent Technologies) is a
leading supplier of duplexers and power amplifiers for mobile handsets
Wireless Semiconductor Division
Baseline: QB GSM Architecture
For 2G, most GSM phones were based on a
common simple architecture supporting all
worldwide bands
3 components for 4 bands
Uses 10 pins on RFIC
Experience from GSM sets expectations:
“adding a band is easy and inexpensive”.
Cost of front end dominated by the PA
Wireless Semiconductor Division
Moving to Multi-Band UMTS: QB GSM + 5 Bands UMTS
Proliferation of new UMTS bands has created
a much more challenging RF front end
24 components for 4 + 5 bands
Uses 37 pins on RFIC
Adding FDD bands isn’t as easy
as adding GSM bands was.
PA cost no longer as dominant
The result is complex:
routing, cost, and size issues
Wireless Semiconductor Division
Higher Isolation Removes Filters
A move to improved RFIC along with higher
isolation duplexers eliminates both Tx and Rx
filters from the UMTS chains. ISO Tx band /
Rx band originally 50/40, but now need 55/50.
Many RFICs adopt differential Rx ports.
14 components for 4 + 5 bands
Uses 25 pins on RFIC
New technology into duplexers
Routing of multiple differential Rx
lines causes major headaches
Still a lot of components.
High Isolation
duplexers
Wireless Semiconductor Division
Implementing Differential
The IC being differential doesn’t mean the duplexer has to be.
4 element network to match to RFIC and
provide DC block
Is really
100 W
200 W
100 W
Any matching at duplexer must
retain balance
Paired high impedance differential lines can be difficult to route while maintaining
magnitude and phase balance, especially if they need to cross into lower board layers.
4 element network to match to RFIC and perform
SE:DE transformation (DC block intrinsic with
FBAR)
Is really
200 W
Phone performance achieved (Band VIII).
2937CH
3013CH
3088CH
-109.5dBm
-109.0dBm
-109.0dBm
50 W
Single 50 ohm transmission line is
straightforward to route even if crossing into
lower board layers. This allows more flexibility in
duplexer placement.
Optional simple, flexible matching
at the duplexer
Wireless Semiconductor Division
Integration Speeds Design
Switch-filter and
PA-switch-filter modules
Intermediate integration for easier design,
better performance.
Dual band PAs for size and cost savings
PA-duplexer has better efficiency than
discretes due to interstage match
Multiplexers improve broadband rejection,
simplify switching
PA switch integration (but are switch
requirements standardized enough?)
6 components for 4 + 5 bands
“by band”
FEMs
SE lines and
baluns to solve
routing
Uses 25 pins on RFIC
Multiplexers
Intermediate integration
simplifies design,
improves performance.
Dual band PAs
Wireless Semiconductor Division
Multiband PAs Are Proposed to Cut Cost
Move to Multi-Band PAs to eliminate PAs. However
this also adds significant loss, from several sources:
1) IL of new switches
2) poorer PAE of PA due to wider loadline
3) poorer PAE to oversizing PA die to handle band
with most loss
4) additional switch loss to stop noise leakage from
common PA on UMTS bands with overlap
Switch-filter
structures
15 components for 4 + 5 bands
Uses 22 pins on RFIC
Significant impact on efficiency:
~100 mA added peak current
(but only a few mA more average current)
Multi-Band
linear PA
Wireless Semiconductor Division
Multi-Mode PAs to Go Even Further
Move to Multi-Band Multi-Mode PAs to further simplify.
Also uses Rx of duplexers for GSM Rx.
Further impact on efficiency:
1) even poorer PAE to oversizing PA die to handle
higher power of GSM: may broach peak current limit
2) “through” for GSM Tx creates noise leakage
path for all bands: more importance on high isolation
(hence lossy) switches.
However sets stage for multi-mode UMTS-LTE
GSM Rx through
duplexers?
Sensitivity impact from increased switch losses and
higher loss of duplexer filters compared to Rx filters,
including BW effects.
15 components for 4 + 5 bands
Uses 14 pins on RFIC
DC-DC
converter
Multi-Band
Multi-Mode PA
Costly insertion loss on GSM Tx (esp. low band)
Architecture may move rather than remove cost
Enough bandwidth for 700 MHz and Band VII?
Wireless Semiconductor Division
Noise Leakage Paths
B1
Noise Leakage paths
(6)
SW1
(5)
Multi-band
multi-mode
PA
(1)
(4)
B2, PCS Rx
GSM High: noise leakage around B1, B2, B3, B4/10, B9
B1: noise leakage around B2
B2: noise leakage path around B3/B9
B3, DCS Rx
GSM Low: noise leakage path around B5, B6, B8
B8: noise leakage path around B5/B6
GSM High
GSM Low
B5, 800 Rx
SW2
B8, 900 Rx
(7)
(3)
Example: When broadcasting on B2, noise from the
common high band PA at 1930-1990 MHz leaks across
SW1 (1) and reaches the antenna switch (3) with minimal
loss. It leaks across the antenna switch, and into the
output of the B2 duplexer, then passes through the
duplexer Rx filter (4) to add to the noise at B2 Rx.
Similarly, noise in the 1930-1980 MHz band leaks across
SW1 (5) and passes through the Tx filter of the B1
duplexer (6) with minimal loss. It then leaks across the
antenna switch (7) and back through the B2 duplexer Rx
filter (4), adding more noise.
Wireless Semiconductor Division
Switches and Isolation
Switch isolation comes from adding series-shunt
pairs of FETs.
While a second pair of FETs doubles the
isolation, it also doubles the insertion loss.
(2nd series)
(1st series)
Thus there is an insertion loss penalty for using
high isolation switches.
(2nd shunt)
(1st shunt)
“Rule of thumb” typical performance:
High band, one pair:
I.L. = 0.4 dB typ, ISO = 18 dB typ.
Low band, one pair:
I.L. = 0.3 dB typ, ISO = 22 dB typ.
Need 10 to 15 dB more ISO than duplexer filter
supplies for minimal impact on isolation: >60 dB
ISO required!
Representative switches
manufacturer
I.L.
Filtronics
ISO
Type (P/N)
Test freq
I.L. @ high for ISO >60
0.85 max / 0.65 typ 30 min / 32 typ
SP4T (FMS2016-001)
2 GHz
1.9 min / 1.3 typ
M/A Com
0.6 typ
SP2T (MASWSS0161V3)
2 GHz
1.8 typ
Peregrine
0.75 max / 0.55 typ 23.5 min / 27.5 typ SP4T (PE42641)
2 GHz
2.25 min / 1.65 typ
Sony
0.6 max / 0.45 typ
1.9 GHz
1.8 max / 1.35 typ
27 typ
25 min
SP5T (a6808865)
Wireless Semiconductor Division
Normalized Cost Comparison
GSM +1 Band
GSM + 3 Bands
GSM + 5 Bands
4.50
4.00
3.50
3.00
switches
2.50
PA
2.00
filters
1.50
1.00
0.50
QB EDGE
QB+ UMTS 1 QB + UMTS QB+ UMTS 1 QB + UMTS
1 MB
MBMM
1-2-5
For QB GSM, PA cost
dominates. However for
added UMTS bands, cost
is increasingly shared
with duplexers
For single band,
discretes are cheaper
than MB or MBMM –
no surprise.
QB + UMTS QB + UMTS QB + UMTS QB + UMTS QB + UMTS
1-2-5 MB
1-2-5 MBMM
1-2-4-5-8
1-2-4-5-8 MB
1-2-4-5-8
MBMM
For tri-band, there
isn’t that much cost
difference – but there
is a performance
difference.
For penta-band, there is a cost
savings from consolidating
PAs – but going MM mostly
just transfers cost from the PA
to the switch.
Wireless Semiconductor Division
Performance Comparison (Current Draw)
GSM peak current, low and high bands
UMTS B-1 peak and average current
600
1600
50
45
500
1500
40
35
400
30
300
25
20
200
1400
B1 peak
B1 avg
15
10
100
GSM L
1300
GSM H
1200
1100
5
M
+
Q
B
Q
B
+
+
UM
TS
UM
TS
124518
UM
24TS
518
M
2B
458
M
BM
M
BM
M
B
M
125
Q
B
+
Q
B
Q
B
+
UM
TS
UM
TS
UM
Q
B
+
TS
UM
125
TS
M
1
TS
125
BM
M
1
TS
UM
Q
B+
+
M
B
1
G
E
ED
UM
Q
B+
Q
B
TS
UM
Q
B
+
1000
Q
B
TS
UM
+
+
Q
B
12451UM
8
2
TS
4518
2M
4B
58
M
BM
M
BM
M
B
M
M
Q
B
Q
B
+
+
UM
TS
UM
TS
UM
+
Q
B
Q
B
125
TS
M
TS
UM
125
BM
M
1
TS
+
UM
Q
B+
Q
B
M
B
1
1
TS
UM
ED
Q
B+
Q
B
125
0
G
E
0
Multi-Band impacts UMTS peak current (~70 mA)
Impact on average current is relatively small (~5 mA)
Multi-Mode impacts GSM current (>100
mA penalty!)
Multi-Mode doesn’t add much additional penalty to UMTS
Multi-Band doesn’t impact GSM
Wireless Semiconductor Division
PA Formats
Optimized
Efficiency
Compatible
Power Control
Conventional –
optimized for min
current at full power
(battery peak current)
Best average current
– optimized for min
current at most
common power levels
(use time)
Bypass – optimized
for min current at
most common, plus
has bypass state
(use time)
PA only
PA with coupler
Integration:
cost, size, performance, time
Combined PAs:
Dual band
Multi-Band
Multi-Band Multi-Mode
PA plus switch
GSM + T/R
UMTS + routing
combined “std elements”
PA plus duplexer
PA with coupler
and detector
Wireless Semiconductor Division
Duplexer Formats
Design vs
Band Properties
Differential vs SE
Easy:
Broad-Band optimized
Gentle roll-off
B1, B4, B6, B9
Medium:
Out-of-band optimized
Moderate Roll-off
B5, B7
Hardest:
In-band optimized
Steep Roll-off
B2, B3, B8
Good for the IC vendor
Hard on layout (routing)
May cost Q (hence IL)
Not truly needed for ISO
Integration:
PA plus duplexer
Multiplexer
Good for layout
Requires baluns
Lowest IL solutions
Front End
Wireless Semiconductor Division
Some Closing Thoughts
Global solutions cost more (at least use more components) and don’t work
as well as optimized local solutions. However they have better economies of
scale and make better use of engineering resources.
There is a difference between a global reference design that demonstrates
the capability of a chipset and a phone that supports a particular geography.
The industry is still learning what is needed to handle data while roaming .
The answer may depend on whether future handsets are primarily voice
appliances or data appliances.
There is plenty of room for component suppliers to offer innovative new
solutions to solve the emerging problems of multi-band multi-mode handsets.
Wireless Semiconductor Division
It sure would be nice if….
1. the folks who decide such things would be more
open to discussing the trade-offs involved prior to
adopting new “industry standards” for product format.
I’d rather eat fusion cuisine than old chestnuts.
2. an opportunity existed for component houses to
discuss possible trade-offs jointly with Service Providers
and OEMs / IC houses / reference design creators, to set
the right balance between performance and cost. I don’t
always like to shop at Wal-Mart.
3. component suppliers had better access to information about IC pin-out so that
complimentary parts could be intelligently matched to chipsets. Blind Man’s Bluff was never my
favorite game.
4. And where is that small, free, lossless, infinite isolation switch, anyway?