User manual for the BGU7008 GPS LNA evaluation board

UM10488
User manual for the BGU7008 GPS LNA evaluation board
Rev. 1.0 — 9 June 2011
User manual
Document information
Info
Content
Keywords
LNA, GPS, BGU7008
Abstract
This document explains the BGU7008 AEC-Q100 qualified GPS low
noise amplifier evaluation board
UM10488
NXP Semiconductors
BGU7008 GPS LNA EVB
Revision history
Rev
Date
Description
1.0
20110609
First Release.
Contact information
For additional information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: [email protected]
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1. Introduction
NXP Semiconductors’ BGU7008 is an AEC-Q100 qualified low-noise amplifier for GPS
receiver applications in a plastic, leadless 6 pin, extremely thin small outline SOT886
package. It has a gain of 18.5 dB and a noise figure of 0.9 dB (incl. board losses) or 0.85
dB (board losses subtracted). It has superior linearity performance to suppress
interference and noise from co-habitation cellular transmitters while retaining sensitivity.
The LNA has been designed using NXP Semiconductors’ advanced 110 GHz fT SiGe:C
process. The BGU7008 only requires two external components, one series inductor for
input matching and one decoupling capacitor. The BGU7008 contains one RF stage and
internal bias that is temperature stabilized. It is also supplied with an enable function
allowing it to be controlled by a logic signal.
The BGU7008 is ideal for use as GPS LNA in smart phones, feature phones and
Portable Navigation Devices.
The GPS LNA evaluation board (EVB), see Fig 1, is designed to evaluate the
performance of the BGU7008 applied as a GPS LNA. In this document, the application
diagram, board layout, bill of materials, and typical results are given, as well as some
explanations on GPS related performance parameters like out-of-band input third-order
intercept point, gain compression under jamming and noise under jamming.
Fig 1. BGU7008 GPS LNA evaluation board
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2. General description
NXP Semiconductors’ BGU7008 GPS low noise amplifier is dedicated for the GNSS
frequency band (GPS, GLONASS and Galileo positioning systems). The integrated
biasing circuit is temperature stabilized, which maintains a constant current over
temperature. It also enables the superior linearity performance of the BGU7008. It is also
supplied with an enable function that allows it to be controlled with a logic signal. In
disabled mode it consumes less than µA.
The output of the BGU7008 is internally matched for 1575.42 MHz whereas only one
series inductor at the input is needed to achieve the best RF performance. Both the input
and output are AC coupled via an integrated capacitor.
Only two external components are required to build a GPS LNA with the following
advantages:
 Low noise;
 High gain;
 High linearity under jamming;
 Very low package height 0.5mm;
 Low current consumption;
 Short power settling time;
The data sheet of the BGU7008 is available, and it is called “SiGe:C Low Noise Amplifier
MMIC for GPS applications”
3. Application Board
The BGU7008 GPS LNA evaluation board simplifies the evaluation of the BGU7008 GPS
LNA for the GPS application. The evaluation board enables testing of the device
performance and requires no additional support circuitry. The board is fully assembled
with the BGU7008, including the input series inductor as well as a decoupling capacitor
to optimize the performance. The board is supplied with two SMA connectors for input
and output connection to RF test equipment. The BGU7008 can operate from a 1.5 V to
2.85 V single supply and consumes about 5mA.
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Application Circuit
The circuit diagram of the evaluation board is shown in Fig 2.
With jumper JU1 the enable pin can be controlled to either to Vcc or GND.
Fig 2. Circuit diagram of the BGU7008 evaluation board
Board Layout
Fig 3. Printed circuit board lay-out of the BGU7008 GPS LNA evaluation board
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PCB layout
A good PCB layout is an essential part of an RF circuit design. The evaluation board of
the BGU7008 can serve as a guideline for laying out a board using the BGU7008. Use
controlled impedance lines for all high frequency inputs and outputs. Bypass V cc with
decoupling capacitors, preferably located as close as possible to the device. For long
bias lines it may be necessary to add decoupling capacitors along the line further away
from the device. Proper grounding of the GND pins is also essential for good RF
performance. Either connect the GND pins directly to the ground plane or through vias, or
do both. The material that has been used for the evaluation board is FR4 using the stack
shown in Fig 4
20um Cu
0.2mm FR4 critical
20um Cu
0.8mm FR4 only for
mechanical rigidity of PCB
20um Cu
Fig 4. Stack of the PCB material
Material supplier is ISOLA DURAVER; r = 4.6 - 4.9: Tan= 0.02
Bill of materials
Table 1 BOM of the BGU7008 GPS LNA EVB v2.1
Designator
Description Footprint
Value
Supplier Name/type
Ac
BGU7008
1.45x1.1mm
PCB
v2.1
35x20mm
BGU7008 GPS LNA EVB
C1
Capacitor
0402
1nF
Murata GRM1555
Decoupling
L1
Inductor
0402
5.6nH
Murata/LQW15A High Q low Rs
Input matching
X1,X2
SMA RF
connector
-
-
Johnson, End launch SMA
RF input/ RF
output
X3
DC header
-
-
Molex, PCB header, Right Angle, 1
row, 3 way 90121-0763
X4
JUMPER
stage
-
-
Molex, PCB header, Vertical, 1 row, Connect Ven to
3 way 90120-0763
Vcc or separate
Ven voltage
JU1
Jumper
Comment
LNA MMIC
142-0701-841
Bias connector
3.1.1 Series inductor
The evaluation board is supplied with Murata LQW15series inductor of 5.6nH. This is a
wire wound type of inductor with high quality factor (Q) and low series resistance (Rs).
This type of inductor is recommended in order to achieve the best noise performance.
High Q inductors from other suppliers can be used. If it is decided to use other low cost
inductors with lower Q and higher Rs the noise performance will degrade.
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4. Required Equipment
In order to measure the evaluation board the following is necessary:

DC Power Supply up to 30 mA at 1.5 V to 2.85 V;

Two RF signal generators capable of generating an RF signal at the operating
frequency of 1575.42 MHz, as well as the jammer frequencies 850 MHz, 1713.42
MHz, 1850 MHz and 1851.42 MHz;

An RF spectrum analyzer that covers at least the operating frequency of 1575.42
MHz as well as a few of the harmonics, so up to 6 GHz should be sufficient;

“Optional” a version with the capability of measuring noise figure is convenient;

Amp meter to measure the supply current (optional);

A network analyzer for measuring gain, return loss and reverse Isolation;

Noise figure analyzer and noise source;

Directional coupler;

Proper RF cables.
5. Connections and setup
The BGU7008 GPS LNA evaluation board is fully assembled and tested. Please follow
the steps below for a step-by-step guide to operate the evaluation board and testing the
device functions.
1. Measure the cable- and directional coupler losses at the frequencies which are used
during the evaluation (1575 MHz, 850 MHz and 1850 MHz). These losses are used
to correct the measured power levels.
2. Connect the DC power supply to the Vcc, and GND terminals. Set the power supply
to the desired supply voltage, between 1.5 V and 2.85 V, but never exceed 3.1 V as it
might damage the BGU7008.
3. Jumper JU1 is connected between the Vcc terminal of the evaluation board and the
Ven pin of the BGU7008.
4. To evaluate the power on settling time ton and the power off settling time toff, it is
also possible to use a separate voltage on the Ven, eventually this voltage can be
supplied by a pulse generator. In this case jumper JU1 should be removed. The
definition of ton is the time from 10 % to 90 % of the maximum signal level and for
toff¬ the time from 90 % to 10 % of the maximum signal level.
5. Connect the RF signal generator and the spectrum analyzer to the RF input and the
RF output of the evaluation board, respectively. Do not turn on the RF output of the
Signal generator yet, set it to -40 dBm output power at 1575.42 MHz, set the
spectrum analyzer at 1575.42 MHz center frequency and a reference level of 0 dBm.
6. Turn on the DC power supply and it should read approximately 5mA.
7. Enable the RF output of the generator; the spectrum analyzer displays a tone of
around –25 dBm at 1575.42 MHz.Instead of using a signal generator and spectrum
analyzer one can also use a network analyzer in order to measure gain as well as inand output return loss.
8. For noise figure evaluation, either a noise-figure analyzer or a spectrum analyzer with
noise option can be used. The use of a 15 dB noise source, like the Agilent 364B is
recommended. When measuring the noise figure of the evaluation board, any kind of
adaptors, cables etc between the noise source and the evaluation board should be
avoided, since this affects the noise performance.
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9. For noise under jamming conditions, the following is needed. A 15dB ENR noise
source, a directional coupler, GPS band pass filter, a noise-figure analyzer or a
spectrum analyzer with noise option can be used. See Fig 11
Fig 5. GPS LNA evaluation board including its connections
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6. Linearity
At the average power levels of –130 dBm that have to be received by a GPS receiver,
the system will not have in-band intermodulation problems caused by the GPS-signal
itself. Strong out-of-band cell phone TX jammers however can cause linearity problems,
and result in third-order intermodulation products in the GPS frequency band. In this
chapter the effects of these Jammer-signals on the Noise and Gain performance of the
BGU7008 are described. The effect of these Jammers on the In-band and Out-of-Band
Third-Order Intercept points are described in more detail in a separate User Manual:
UM10489: 2-Tone Test BGU7004 and BGU7008 GPS LNA.
6.1 1 dB gain compression at 1575 MHz with 850 MHz or 1850 MHz Jammers
As already stated before, signal levels in the GPS frequency band of –130 dBm average
will not cause linearity problems in the GPS band itself. This of course is also valid for the
1 dB gain compression in-band. The 1 dB compression point at 1575 MHz caused by cell
phone TX jammers however is important. Measurements have been carried out using the
set-up shown in Fig 6. The jammer signal is coupled via a directional coupler to the DUT.
For the P1dB measurements this not required, but connecting it this way the setup can
also be used for NF-measurements as described in the next paragraph.
Fig 6. Setup for 1 dB compression with jammers
The gain of the DUT was measured between port RFin and RFout of the EVB at the
GPS frequency 1575 MHz, while simultaneously a jammer power signal was swept at the
20 dB attenuated input port of the Directional Coupler. Please note that the drive power
of the jammer is 20 dB lower at the input of the DUT caused by the directional coupler.
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The figures below show the supply-current (Icc) and gain compression curves with 850
MHz and 1850 MHz jammers. At 1 dB Gain drop the Jammer-Generator read out for 850
MHz jammer is +5.6 dBm (Vcc=2.85 V). Taking into account the approx 20 dB
attenuation of the directional coupler this means Pi1 dB = –14.74 dBm (Figure 8). For
1850 MHz the Jammer-Generator read out is +12.8 dBm (Vcc=2.85 V. Taking into
account the approx 20 dB attenuation of the directional coupler this means Pi1 dB = –
7.54 dBm). (Figure10).
Gain vs Jammer power at 850MHz
Icc vs Jammer power at 850MHz
(Pin 1575MHz=-45dBm)
14
22.00
13
21.00
12
20.00
11
19.00
10
18.00
9
Vcc=1.5V
Vcc=1.8V
8
Gain [dB]
Icc [mA]
(Pin 1575MHz=-45dBm)
17.00
Vcc=1.8V
16.00
Vcc=2.85V
7
15.00
6
14.00
5
13.00
4
-40.00
Vcc=1.5V
Vcc=2.85V
12.00
-35.00
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
-40.00
-35.00
P_Jammer at input DUT [dBm]
-30.00
-25.00
(1) Jammer frequency is 850 MHz
-10.00
-5.00
0.00
Fig 8. Gain versus jammer power
Gain vs Jammer power at 1850MHz
Icc vs Jammer power at 1850MHz
(Pin 1575MHz=-45dBm)
(Pin 1575MHz=-45dBm)
14
22.00
13
21.00
12
20.00
11
19.00
10
18.00
9
Vcc=1.5V
Vcc=1.8V
8
Vcc=2.85V
Gain [dB]
Icc [mA]
-15.00
(2) Jammer frequency is 850 MHz
Fig 7. Icc versus jammer power
17.00
15.00
6
14.00
5
13.00
4
Vcc=1.5V
Vcc=1.8V
16.00
7
-40.00
-20.00
P_Jammer at input DUT [dBm]
Vcc=2.85V
12.00
-35.00
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
-40.00
P_Jammer at input DUT [dBm]
(3) Jammer frequency is 1850 MHz
Fig 9. Icc versus jammer power
-30.00
-25.00
-20.00
-15.00
-10.00
-5.00
0.00
P_Jammer at input DUT [dBm]
(4) Jammer frequency is 1850 MHz
Fig 10. Gain versus jammer power
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7. Noise figure as function of jammer power at 850 MHz and 1850 MHz
Noise figure under jamming conditions is a measure of how the LNA behaves when e.g.
a GSM TX interfering signal is at the input of the GPS antenna. To measure this behavior
the setup shown in Fig 11 is used.
The jammer signal is coupled via a directional coupler to the DUT: this is to avoid the
jammer signal damaging the noise source. The GPS BPF is needed to avoid driving the
second-stage LNA in saturation.
For the Jammer-Generator a low Phase-Noise type is advised. This is to avoid extra
noise caused by the Jammer-Generator at measurement frequency (1575 MHz).
Fig 11. Noise under jamming measurement setup
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In the figures below the supply-current (Icc), the noise figure (NF) and gain as function of
jammer power are given for 850 MHz and 1850 MHz jammer signals.
Icc vs Jammer Power at 1850MHz
15
14
14
13
13
12
12
11
11
10
Vcc=1.5V
9
Icc [mA]
Icc [mA]
Icc vs Jammer Power at 850MHz
15
Vcc=1.8V
8
10
Vcc=1.5V
9
Vcc=1.8V
8
Vcc=2.85V
7
7
6
6
5
5
Vcc=2.85V
4
4
-40
-35
-30
-25
-20
-15
-10
-40
-5
-35
-30
-25
-20
-15
-10
-5
P_jammer at input DUT [dBm]
P_jammer at input DUT [dBm]
(5) Jammer frequency is 850 MHz
(6) Jammer frequency is 1850 MHz
Fig 12. Icc versus jammer power
Fig 13. Icc versus jammer power
NF vs Jammer Power at 850MHz
NF vs Jammer Power at 1850MHz
3
3
2.5
2.5
2
2
Vcc=1.5V
1.5
Vcc=1.8V
NF [dB]
3.5
NF [dB]
3.5
Vcc=1.5V
1.5
Vcc=1.8V
Vcc=2.85V
Vcc=2.85V
1
1
0.5
0.5
0
0
-40
-35
-30
-25
-20
-15
-10
-5
-40
P_jammer at input DUT [dBm]
(7) Jammer frequency is 850 MHz
Fig 14. NF at 1.575 GHz versus jammer power
-30
-25
-20
-15
-10
-5
P_jammer at input DUT [dBm]
(8) Jammer frequency is 1850 MHz
Fig 15. NF at 1.575 GHz versus jammer power
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8. Typical Evaluation Board results
Table 2, typical results measured on the Evaluation Boards.
Operating Frequency is f=1575.42 MHz unless otherwise specified; Temp = 25 C.
Parameter
Symbol
BGU7008
BGU7008
BGU7008
Unit
Supply Voltage
Vcc
1.5
1.8
2.85
V
Supply Current
Icc
3.4
4.8
6.1
mA
Noise Figure
NF
0.9
0.9
0.9
dB
Pin < -40 dBm, no jammer
Power Gain
Gp
16.5
18.5
20.5
dB
Pin < -40 dBm, no jammer
Input Return Loss
RLin
5
7
dB
Pin < -40 dBm, no jammer
Output Return Loss
RLout
12
18
dB
Pin < -40 dBm, no jammer
Reverse Isolation
ISLrev
22
24
dB
Pin < -40 dBm, no jammer
Input 1dB Gain Compression
Pi1dB
-13
-12
-11
Compression
Input third order intercept point
dBm
IP3i
4
4
5
dBm
[1]
[2]
Remarks
[1]
The NF and Gain figures are being measured at the SMA connectors of the evaluation board, so the losses of the connectors and the
PCB of approximately 0.1dB are not subtracted.
[2]
Jammers at f1 = f+138 MHz and f2 = f+276 MHz, where f = 1575.42 MHz.
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9. Legal information
9.1 Definitions
Draft — The document is a draft version only. The content is still under
internal review and subject to formal approval, which may result in
modifications or additions. NXP Semiconductors does not give any
representations or warranties as to the accuracy or completeness of
information included herein and shall have no liability for the consequences
of use of such information.
9.2 Disclaimers
Limited warranty and liability — Information in this document is believed to
be accurate and reliable. However, NXP Semiconductors does not give any
representations or warranties, expressed or implied, as to the accuracy or
completeness of such information and shall have no liability for the
consequences of use of such information.
In no event shall NXP Semiconductors be liable for any indirect, incidental,
punitive, special or consequential damages (including - without limitation lost profits, lost savings, business interruption, costs related to the removal
or replacement of any products or rework charges) whether or not such
damages are based on tort (including negligence), warranty, breach of
contract or any other legal theory.
Notwithstanding any damages that customer might incur for any reason
whatsoever, NXP Semiconductors’ aggregate and cumulative liability
towards customer for the products described herein shall be limited in
accordance with the Terms and conditions of commercial sale of NXP
Semiconductors.
Right to make changes — NXP Semiconductors reserves the right to make
changes to information published in this document, including without
limitation specifications and product descriptions, at any time and without
notice. This document supersedes and replaces all information supplied prior
to the publication hereof.
Suitability for use — NXP Semiconductors products are not designed,
authorized or warranted to be suitable for use in life support, life-critical or
safety-critical systems or equipment, nor in applications where failure or
malfunction of an NXP Semiconductors product can reasonably be expected
to result in personal injury, death or severe property or environmental
damage. NXP Semiconductors accepts no liability for inclusion and/or use of
NXP Semiconductors products in such equipment or applications and
therefore such inclusion and/or use is at the customer’s own risk.
Applications — Applications that are described herein for any of these
products are for illustrative purposes only. NXP Semiconductors makes no
representation or warranty that such applications will be suitable for the
specified use without further testing or modification.
whether the NXP Semiconductors product is suitable and fit for the
customer’s applications and products planned, as well as for the planned
application and use of customer’s third party customer(s). Customers should
provide appropriate design and operating safeguards to minimize the risks
associated with their applications and products.
NXP Semiconductors does not accept any liability related to any default,
damage, costs or problem which is based on any weakness or default in the
customer’s applications or products, or the application or use by customer’s
third party customer(s). Customer is responsible for doing all necessary
testing for the customer’s applications and products using NXP
Semiconductors products in order to avoid a default of the applications and
the products or of the application or use by customer’s third party
customer(s). NXP does not accept any liability in this respect.
Export control — This document as well as the item(s) described herein
may be subject to export control regulations. Export might require a prior
authorization from national authorities.
Evaluation products — This product is provided on an “as is” and “with all
faults” basis for evaluation purposes only. NXP Semiconductors, its affiliates
and their suppliers expressly disclaim all warranties, whether express,
implied or statutory, including but not limited to the implied warranties of noninfringement, merchantability and fitness for a particular purpose. The entire
risk as to the quality, or arising out of the use or performance, of this product
remains with customer.
In no event shall NXP Semiconductors, its affiliates or their suppliers be
liable to customer for any special, indirect, consequential, punitive or
incidental damages (including without limitation damages for loss of
business, business interruption, loss of use, loss of data or information, and
the like) arising out the use of or inability to use the product, whether or not
based on tort (including negligence), strict liability, breach of contract, breach
of warranty or any other theory, even if advised of the possibility of such
damages.
Notwithstanding any damages that customer might incur for any reason
whatsoever (including without limitation, all damages referenced above and
all direct or general damages), the entire liability of NXP Semiconductors, its
affiliates and their suppliers and customer’s exclusive remedy for all of the
foregoing shall be limited to actual damages incurred by customer based on
reasonable reliance up to the greater of the amount actually paid by
customer for the product or five dollars (US$5.00). The foregoing limitations,
exclusions and disclaimers shall apply to the maximum extent permitted by
applicable law, even if any remedy fails of its essential purpose.
9.3 Trademarks
Notice: All referenced brands, product names, service names and
trademarks are property of their respective owners.
Customers are responsible for the design and operation of their applications
and products using NXP Semiconductors products, and NXP
Semiconductors accepts no liability for any assistance with applications or
customer product design. It is customer’s sole responsibility to determine
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10. Contents
1.
Introduction ......................................................... 3
2.
General description ............................................. 4
3.
Application Board ............................................... 4
Application Circuit ............................................................... 5
Board Layout ...................................................................... 5
PCB layout .......................................................................... 6
Bill of materials ................................................................... 6
3.1.1
Series inductor ................................................... 6
4.
Required Equipment ........................................... 7
5.
Connections and setup ....................................... 7
6.
Linearity ............................................................... 9
6.1
1dB gain compression at 1575 MHz with 850
MHz or 1850 MHz Jammers............................... 9
7.
Noise figure as function of jammer power at
850 MHz and 1850 MHz ..................................... 11
8.
Typical Evaluation Board results ..................... 13
9.
Legal information .............................................. 14
9.1
Definitions ........................................................ 14
9.2
Disclaimers....................................................... 14
9.3
Trademarks ...................................................... 14
10.
Contents ............................................................. 15
Please be aware that important notices concerning this document and the product(s)
described herein, have been included in the section 'Legal information'.
© NXP B.V. 2011. All rights reserved.
For more information, please visit: http://www.nxp.com
For sales office addresses, email to: [email protected]
Date of release: 9 June 2011
Document identifier: UM10488