Hirotaka Sugawara, Yoshiaki Yoshihara, Kenichi Okada, and Kazuya MasuPrecision and Intelligence Laboratory, Tokyo Institute of Technology, Japan
Reconfigurable CMOS LNA for Software Defined Radio Using Variable Inductor
Background Reconfigurable RF Circuit
Multi-band RF front-end Architectures
Conclusion
Tunable LNA
L150Ω
50Ω
Vgs=0.65 V
Vdd=1.8 V
L2
L=0.2 µmW=5 µmm=60
L=0.2 µmW=5 µmm=60Pin
Pout
Wireless Standardsn Mobile phone 900MHz, 1.5GHz, 2GHz
(+ 800MHz, 1.7GHz, 1.9GHz for the new system)
(+ 800MHz, 900MHz, 1.8GHz, 1.9GHz for GSM)
n WLAN 802.11b/g, Bluetooth 2.4GHz
n WLAN 802.11a/n 5GHz
n GPS 1.2GHz/1.5GHzn DTV 470 MHz~770 MHz
Purpose
PA
LNA
LO
LPF DAC
ADC
SW
RF Front-End
I Q
MIX
MIX LPF
Bas
eban
d LS
I
Proposed Concept
To provide multiple functions to circuitsMulti-function
Reconfigurable RF Circuit Design K. Okada, et al., in ASP- DAC, Jan. 2005, pp.683-686.
A multi-band/mode circuit for wireless communication chips
Self-compensation
Si CMOS Technology provide
Wireless Communication Circuits
Realization of Si CMOS RF circuits
Reconfigurable RF Circuit
RF circuit is controlled by digital circuit
Architecture
Proposed Architecture
Variable InductorVariable Inductor
The inductance continuously varies depending on the position of the metal plate.
The metal plate shields the magnetic flux whichpenetrate the inductor.
h
Spiral Inductor
Metal Plate
consists of a planar-type spiral inductor and a metal plate.
MEMS Parallel Plate actuator
V. M. Lubecke, and J. -C. Chiao: The IEEE 4th Int. Conf. on Telecommunications in Modern Satellite, Cable and Broadcasting Services, 1999 p. 1stationary electrode
movable electrode
Moving system is realized to use MEMS actuator
Measurement
Turns : 3Line width : 10 µmLine space : 1.2 µmOuter diameter : 300 µm
0.9 pF
0.6 pF
0.18 µm M5 CMOS Process1.28 mm
0.97
mm
1.28 mm
0.97
mm
Variable Characteristic
0 5 10 15 20Frequency [GHz]
PG
[dB
]
-20
-10
20
10@ 1.9 GHzPG=14.2 dBPin=-27 dBm
0
0 5 10 15 20Frequency [GHz]
-100
-60
-20
-40
S12
[dB
]
@ 1.9 GHzPG=-31.0 dBPin=-27 dBm
-80
-30 -20 -10 0 5Pin [dBm]
-5
5
Pou
t[dB
m] 0
-10
-15
0 5 10 15 20Frequency [GHz]
S22
[dB
]S
11[d
B]
-20
-10
5
0
-5
S11
S22
S22 S11
1 2 3 4 5Frequency [GHz]
NF
[dB
]
10
4
8
6
@ 1.9 GHzNF=5.2 dB
-15
-5-15-25
@ 1.9 GHzS11=-11.0 dBS22=-12.7 dBPin=-27 dBm
Freq.=1.9 GHzInput P1dB=-15.8 dBm
1.898 1.899 1.901 1.903Frequency [GHz]
Am
plitu
de [d
B]
-1401.900 1.902
-120
-80
-40
0
-60
-20
-100
-52.5 dBm @ 1.899 GHz-13.1 dBm @ 1.900 GHz-13.1 dBm @ 1.901 GHz-53.2 dBm @ 1.902 GHz
Power= -27 dBmIIP3 =-7.2 dBm
high density integrationhigh frequency performanceLow fabrication cost
Wireless communication standards use severalfrequency bands.
Multi standard Baseband
Software Defined Radio (SDR)
It is necessary for global roaming using SDRto realize Multi-band RF front-end
400 MHz-6 GHz
To realize Multi-band RF front-end
To provide a compensating mechanismProcess variations, Modeling error, Temperature etc.
Control Digital Circuit
Proposed Tunable LNA
Multi-band Down convertor
Wide-band Antenna
f
Gai
n ...
TuningLNA Down convertor
・・
・
LNA Down convertor
f...G
ain
Using some signal paths for each frequency band
It needs large chip area to extend the number of communication standards.
Wide-band LNA
Gai
n
Multi-band Down convertor
Wide-band Antenna
f
Distributed amplifier needs large chip area and power consumption.
Using Distribute amplifier
multi-band LNA using resonator
Multi-band Down convertor
Wide-band Antenna
f
Gai
n ...
The approach require large chip area due to many resonators.
Using some input resonatorsWide-tunable CMOS LNA is realized by the variable inductor.
The proposed LNA achieves wide-tuning range with narrow-band gain and can be used for reconfigurable RF front-end.
Turns : 3Line width : 20 µmLine space : 1.2 µmOuter diameter : 400 µm
L1 L2
L1 L2
Q
4.5
3.5
3.0
4.0
@1.9 GHzLmax/Lmin=1.5
Height of plate h [µm]
3
L [n
H]
0 100 400
6
5
300200 500
4
Q
4
3
2
Height of plate h [µm]
3
L [n
H]
0 100 400
7
5
300200 500
4
6
@1.9 GHzLmax/Lmin=2.0
1Frequency [GHz]
0.1
Q
4
3
2
1
100
Decrease in Metal Plate Height
1Frequency [GHz]
0.1
L [n
H]
4
2
100
10
8
6
Decrease in Metal Plate Height
h=10 µmh=15 µmh=20 µmh=30 µm
h=50 µmh=100 µmw/o Metal plate
1Frequency [GHz]
0.1
Q
4
3
2
1
100
Decrease in Metal Plate Height
1Frequency [GHz]
0.1
L [n
H]
4
2
100
10
8
6
Decrease in Metal Plate Height
L1
L2h=10 µmh=15 µmh=20 µmh=30 µm
h=50 µmh=100 µmw/o Metal plate
Basic Characteristic
Freq. [GHz]Vdd [V]
Idd [mA]PG [dB]
S22 [dB]S11 [dB]
NF [dB]
IIP3 [dBm]Input P1dB [dBm]
1.91.8
7.414.2-11.0-12.75.2
-15.8-7.2
Vgs [V] 0.65
Summary of Performance
1 2 4 5Frequency [GHz]
PG
[dB
]
15
5
03
10
1 2 3 4 5Frequency [GHz]
NF
[dB
]
10
4
8
6
h=10 µmh=15 µmh=20 µmh=30 µmh=50 µmh=100 µmw/o Metal Plate
Noise Figure (NF) : Shift to higher frequency as metal plate inserts
Si CMOS Tunable LNA using the on-chip variable inductors for the SDRThe variable ratios of the variable inductors are over 1.5. The proposed LNA achieves PG of over 10 dB from 1.6 GHz to 3.2 GHz. The minimum NF is shifted to higher frequency as inductances vary.
This tunable LNA is quite useful for multi-band RF communication system with the reconfigurable RF circuit design.
h
Spiral Inductor
Metal Plate
Power Gain (PG) : 15 dB and over 10 dB from 1.6 GHz to 3.2 GHz.
Decrease in Metal Plate Height
Decrease in Metal Plate Height
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