Texas Instruments | AN110 – Using CC1190 Front End with CC112x/CC120x under FCC 15.247 (Rev. B) | Application notes | Texas Instruments AN110 – Using CC1190 Front End with CC112x/CC120x under FCC 15.247 (Rev. B) Application notes

Texas Instruments AN110 – Using CC1190 Front End with CC112x/CC120x under FCC 15.247 (Rev. B) Application notes
Application Note AN110
Using the CC1190 Front End with CC112x and CC120x under
FCC 15.247
By Torstein Ermesjø
Keywords





1
Range Extender
FCC Section 15.247
External PA
External LNA
CC1120




CC1121
CC1125
CC120x
CC1190
Introduction
The CC112x family of devices is fully
integrated single-chip radio transceivers
designed for high performance at very low
power and low voltage operation in cost
effective wireless systems. All filters are
integrated, removing the need for costly
external IF filters. The device is mainly
intended for the ISM (Industrial, Scientific
and Medical) and SRD (Short Range
Device) frequency bands at 164-192 MHz,
410-480 MHz and 820-960 MHz.
The CC1190 is a range extender for 850950 MHz RF transceivers, transmitters,
and System-on-Chip devices from Texas
Instruments. It increases the link budget by
providing a power amplifier (PA) for
increased output power, and a low-noise
amplifier (LNA) with low noise figure for
improved receiver sensitivity in addition to
switches and RF matching for simple
design of high performance wireless
systems.
This application note outlines the expected
performance when using a CC1120CC1190 design under FCC Section 15.247
in the 902-928 MHz frequency band. This
application note assumes the reader is
familiar with CC1120 and FCC 15.247
regulatory limits. The reader is referred to
[1] and [5] for details.
The application note is also applicable for
CC1121, CC1125, and CC120x.
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Application Note AN110
Table of Contents
KEYWORDS.............................................................................................................................. 1
1
INTRODUCTION ............................................................................................................. 1
2
ABBREVIATIONS ........................................................................................................... 2
3
ABSOLUTE MAXIMUM RATINGS ................................................................................. 3
4
ELECTRICAL SPECIFICATIONS ................................................................................... 3
4.1
OPERATING CONDITIONS............................................................................................ 3
4.2
CURRENT CONSUMPTION ........................................................................................... 3
4.3
RECEIVE PARAMETERS .............................................................................................. 4
4.3.1
Typical RX Performance vs. Temperature and VDD ........................................................ 5
4.3.2
Received Signal Strength Indicator (RSSI) ....................................................................... 9
4.4
TRANSMIT PARAMETERS .......................................................................................... 11
4.4.1
Typical TX Performance vs. Temperature and VDD ...................................................... 12
4.4.2
Duty Cycling ................................................................................................................... 16
4.4.3
Typical TX Parameters vs. Load Impedance .................................................................. 17
4.5
MEASUREMENT EQUIPMENT ..................................................................................... 19
5
CONTROLLING THE CC1190...................................................................................... 19
6
SMARTRF STUDIO AND TRXEB ................................................................................ 19
6.1
SMARTRF STUDIO ................................................................................................... 19
6.2
TRXEB ................................................................................................................... 20
7
REFERENCE DESIGN.................................................................................................. 20
7.1
POWER DECOUPLING ............................................................................................... 20
7.2
INPUT/ OUTPUT MATCHING AND FILTERING ............................................................... 20
7.3
BIAS RESISTOR........................................................................................................ 21
7.4
SAW FILTER ........................................................................................................... 21
7.5
PCB LAYOUT CONSIDERATIONS ............................................................................... 21
7.6
SHIELDING ............................................................................................................... 21
8
DISCLAIMER ................................................................................................................ 22
9
REFERENCES .............................................................................................................. 22
10
GENERAL INFORMATION ........................................................................................... 22
10.1
DOCUMENT HISTORY ............................................................................................... 22
2
Abbreviations
EB
EM
FCC
HGM
LNA
LGM
PA
PCB
PER
RF
RSSI
RX
TrxEB
TX
Evaluation Board
Evaluation Module
Federal Communications Commission
High Gain Mode
Low Noise Amplifier
Low Gain Mode
Power Amplifier
Printed Circuit Board
Packet Error Rate
Radio Frequency
Receive Signal Strength Indicator
Receive, Receive Mode
SmartRF Transceiver EB
Transmit, Transmit Mode
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Application Note AN110
3
Absolute Maximum Ratings
The absolute maximum ratings and operating conditions listed in the CC1120 datasheet [1]
and the CC1190 datasheet [3] must be followed at all times. Stress exceeding one or more of
these limiting values may cause permanent damage to any of the devices.
4
Electrical Specifications
Note that the characteristics in Chapter 4 are only valid when using the CC1120-CC1190EM
915 MHz reference design [4] and register settings recommended by the SmartRF Studio
software [6].
4.1
Operating Conditions
Parameter
Min
Max
Unit
Operating Frequency
Operating Supply Voltage
Operating Temperature
850
2.0
-40
950
3.6
+85
MHz
V
°C
Table 4.1. Operating Conditions
4.2
Current Consumption
TC = 25°C, VDD = 3.0 V, f = 915 MHz if nothing else is stated. All parameters are measured
on the CC1120-CC1190EM 915 MHz reference design [4] with a 50  load.
Parameter
Condition
1
Receive Current, HGM
Receive Current, LGM
Transmit Current
Typical
Unit
1.2 kbps, 2FSK, ±4 kHz deviation
24
mA
50 kbps, 2GFSK, ±25 kHz deviation
25
mA
200 kbps, 4GFSK, ±82.76 kHz
deviation
25
mA
1.2 kbps, 2FSK, ±4 kHz deviation
23
mA
50 kbps, 2GFSK, ±25 kHz deviation
24
mA
200 kbps, 4GFSK, ±82.76 kHz
deviation
24
mA
PA_CFG2 = 0x77 (+26dBm)
PA_CFG2 = 0x71 (+25dBm)
PA_CFG2 = 0x6B (+24dBm)
PA_CFG2 = 0x67 (+23dBm)
PA_CFG2 = 0x63 (+22dBm)
PA_CFG2 = 0x60 (+21dBm)
PA_CFG2 = 0x5D (+20dBm)
PA_CFG2 = 0x5A (+19dBm)
PA_CFG2 = 0x58 (+18dBm)
PA_CFG2 = 0x55 (+17dBm)
PA_CFG2 = 0x53 (+16dBm)
401
361
317
284
232
253
210
190
177
160
150
mA
370
nA
Power Down Current
Table 4.2. Current Consumption
1
Input signal at -80 dBm
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Application Note AN110
4.3
Receive Parameters
TC = 25°C, VDD = 3.0 V, f = 915 MHz if nothing else is stated. All parameters are measured
on the CC1120-CC1190EM 915 MHz reference design [4] with a 50  load.
Parameter
Condition
Typical
Unit
1.2 kbps, 2FSK, ±4 kHz deviation, 10 kHz RX filter
bandwidth. See Figure 4.1
-125.5
dBm
9.6 kbps, 4GFSK, ±2.1 kHz deviation, 9.615 kHz RX filter
bandwidth
-118.1
dBm
50 kbps, 2GFSK, ±25 kHz deviation, 100 kHz RX filter
bandwidth. See Figure 4.2
-112.2
dBm
150 kbps, 4GFSK, ±82.76 kHz deviation, 200 kHz RX
filter bandwidth
-106.8
dBm
200 kbps, 4GFSK, ±82.76 kHz deviation, 200 kHz RX
filter bandwidth
-105.7
dBm
4.8 kbps, ASK, 66.6 kHz RX filter bandwidth
-117.1
dBm
1.2 kbps, 2FSK, ±4 kHz deviation, 10 kHz RX filter
bandwidth
-113.9
dBm
50 kbps, 2GFSK, ±25 kHz deviation, 100 kHz RX filter
bandwidth
-100.8
dBm
200 kbps, 4GFSK, ±82.76 kHz deviation, 200 kHz RX
filter bandwidth
-94.3
dBm
Saturation, HGM
Maximum input power level for 1% BER
+10
dBm
Saturation, LGM
Maximum input power level for 1% BER
+10
dBm
Selectivity and
Blocking,
HGM
1.2 kbps, 2FSK, ±4 kHz deviation (see Figure 4.7 and
Figure 4.8)
±2 MHz from wanted signal
±10 MHz from wanted signal
74
80
dB
50 kbps, 2GFSK, ±25 kHz deviation (see Figure 4.9 and
Figure 4.10)
±2 MHz from wanted signal
±10 MHz from wanted signal
65
68
dB
Radiated measurement @3.6 GHz
-61
dBm
2
Sensitivity , HGM
2
Sensitivity , LGM
Spurious
emission, HGM
Table 4.3. Receive Parameters
2
Sensitivity limit is defined as 1% bit error rate (BER). Packet length is 3 bytes.
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Application Note AN110
4.3.1
Typical RX Performance vs. Temperature and VDD
TC = 25°C, VDD = 3.0 V, f = 915 MHz if nothing else is stated. All parameters are measured
on the CC1120-CC1190EM 915 MHz reference design [4] with a 50  load.
Sensitivity 1.2kbps 4kHz dev 2FSK CC1120+CC1190 Detailed data 915.000000
-124
-124.5
Sensitivity [dBm]
-125
-125.5
-126
2.00V Avg
3.00V Avg
3.60V Avg
-126.5
-127
-40
-20
0
20
40
Temperature [degC]
60
80
100
Figure 4.1. Typical Sensitivity vs. Temperature and Power Supply Voltage, HGM, 1.2 kbps
Sensitivity 50kbps 25kHz dev 2GFSK CC1120+CC1190 Detailed data 915.000000
-110.5
-111
Sensitivity [dBm]
-111.5
-112
-112.5
-113
2.00V Avg
3.00V Avg
3.60V Avg
-113.5
-114
-40
-20
0
20
40
Temperature [degC]
60
80
Figure 4.2. Typical Sensitivity vs. Temperature and Power Supply Voltage, HGM, 50 kbps
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Application Note AN110
Sensitivity 200kbps 82.76kHz dev 4GFSK CC1120+CC1190 Detailed data 915.000000
-104
-104.5
Sensitivity [dBm]
-105
-105.5
-106
-106.5
2.00V Avg
3.00V Avg
3.60V Avg
-107
-107.5
-40
-20
0
20
40
Temperature [degC]
60
80
100
Figure 4.3. Typical Sensitivity vs. Temperature and Power Supply Voltage, HGM, 200
kbps
Sensitivity 1.2kbps 4kHz dev 2FSK CC1120+CC1190 Detailed data 915.000000
-112
-112.5
-113
Sensitivity [dBm]
-113.5
-114
-114.5
-115
2.00V Avg
3.00V Avg
3.60V Avg
-115.5
-116
-116.5
-117
-40
-20
0
20
40
Temperature [degC]
60
80
Figure 4.4. Typical Sensitivity vs. Temperature and Power Supply Voltage, LGM, 1.2 kbps
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Application Note AN110
Sensitivity 50kbps 25kHz dev 2GFSK CC1120+CC1190 Detailed data 915.000000
-98.5
-99
-99.5
Sensitivity [dBm]
-100
-100.5
-101
-101.5
-102
2.00V Avg
3.00V Avg
3.60V Avg
-102.5
-103
-103.5
-40
-20
0
20
40
Temperature [degC]
60
80
100
Figure 4.5. Typical Sensitivity vs. Temperature and Power Supply Voltage, LGM, 50 kbps
Sensitivity 200kbps 82.76kHz dev 4GFSK CC1120+CC1190 Detailed data 915.000000
-92
-92.5
-93
Sensitivity [dBm]
-93.5
-94
-94.5
-95
-95.5
2.00V Avg
3.00V Avg
3.60V Avg
-96
-96.5
-97
-40
-20
0
20
40
Temperature [degC]
60
80
Figure 4.6. Typical Sensitivity vs. Temperature and Power Supply Voltage, LGM, 200 kbps
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Application Note AN110
Figure 4.7. Typical Blocking, 1.2 kbps
Figure 4.8. Typical Selectivity, 1.2 kbps
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Application Note AN110
Figure 4.9. Typical Blocking, 50 kbps
Figure 4.10. Typical Selectivity, 50 kbps
4.3.2
Received Signal Strength Indicator (RSSI)
The CC1120-CC1190 RSSI readouts can be converted to an absolute level in dBm by
subtracting an offset. A CC1120-CC1190 design has a different offset value compared to a
standalone CC1120 design due to the CC1190 external LNA gain and the SAW filter insertion
loss. Table 4.4 gives the typical offset value for HGM and LGM. Refer to the CC1120 data
sheet [1] for more details on how to convert the RSSI readout to an absolute power level in
dBm.
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Application Note AN110
HGM
107.5
LGM
91.5
Table 4.4. Typical RSSI Offset Values
Figure 4.11. Typical RSSI vs. Input Power Level, HGM, 1.2 kbps, 20 kHz RX BW
Figure 4.12. Typical RSSI vs. Input Power Level, LGM, 1.2 kbps, 20 kHz RX BW
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Application Note AN110
4.4
Transmit Parameters
TC = 25°C, VDD = 3.0 V, f = 915 MHz if nothing else is stated. All parameters are measured
on the CC1120-CC1190EM 915 MHz reference design [4] with a 50  load, except for the
load-pull measurements. Radiated measurements are done with the kit antenna.
Parameter
Condition
Typical
Unit
PA_CFG2 = 0x77, 3.6 V
27.0
PA_CFG2 = 0x77
PA_CFG2 = 0x71
PA_CFG2 = 0x6B
PA_CFG2 = 0x67
PA_CFG2 = 0x63
PA_CFG2 = 0x60
PA_CFG2 = 0x5D
PA_CFG2 = 0x5A
PA_CFG2 = 0x58
PA_CFG2 = 0x55
PA_CFG2 = 0x53
25.7
25.0
24.0
23.1
22.0
21.1
20.1
19.0
18.2
17.0
16.1
Efficiency, HGM
PA_CFG2 = 0x77
PA_CFG2 = 0x71
PA_CFG2 = 0x6B
PA_CFG2 = 0x67
PA_CFG2 = 0x63
PA_CFG2 = 0x60
31
29
27
24
21
19
%
Spurious emission
with PATABLE = 0x6B, HGM
Conducted below 1 GHz
Conducted above 1 GHz
nd
Conducted 2 harmonic
nd
Conducted 3 harmonic
nd
Radiated 2 harmonic
nd
Radiated 3 harmonic
-65
-52
-10
-47
-22
-44
dBm
20 dB bandwidth, HGM
1.2 kbps, 2FSK, ±4 kHz deviation
9.6 kbps, 4GFSK, ±2.1 kHz deviation
50 kbps, 2GFSK, ±25 kHz deviation
150 kbps, 4GFSK, ±82.76 kHz deviation
200 kbps, 4GFSK, ±82.76 kHz deviation
12.5
9.6
115
250
320
kHz
Output power; HGM
Stability, HGM
Maximum VSWR
with PA_CFG = 0x77
+85˚C:
VDD: 3.6 V
VDD: 3.0 V
7
10
+25˚C:
VDD: 3.6 V
VDD: 3.0 V
7
5
-40˚C:
VDD: 3.6 V
VDD: 3.0 V
4
2.8
dBm
Table 4.5. Transmit Parameters
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Application Note AN110
4.4.1
Typical TX Performance vs. Temperature and VDD
TC = 25°C, VDD = 3.0 V, f = 915 MHz if nothing else is stated. All parameters are measured
on the CC1120-CC1190EM 915 MHz reference design [4] with a 50  load.
Output Power Detailed data 77
28
27
Output power [dBm]
26
25
24
2.00V Avg
3.00V Avg
3.60V Avg
23
22
21
20
-40
-20
0
20
40
Temperature [degC]
60
80
Figure 4.13. Typical Output Power vs. Temperature and Power Supply Voltage. PA_CFG2
= 0x77
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Application Note AN110
Output Power Detailed data 6B
27
26
2.00V Avg
3.00V Avg
3.60V Avg
25
Output power [dBm]
24
23
22
21
20
19
18
17
-40
-20
0
20
40
Temperature [degC]
60
80
Figure 4.14. Typical Output Power vs. Temperature and Power Supply Voltage. PA_CFG2
= 0x6B
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Application Note AN110
Power Consumption Detailed data 77
550
500
2.00V Avg
3.00V Avg
3.60V Avg
Current [mA]
450
400
350
300
250
200
-40
-20
0
20
40
Temperature [degC]
60
80
100
Figure 4.15. Typical TX Current Consumption vs. Temperature and Power Supply Voltage.
PA_CFG2 = 0x77
Power Consumption Detailed data 6B
400
2.00V Avg
3.00V Avg
3.60V Avg
350
Current [mA]
300
250
200
150
-40
-20
0
20
40
Temperature [degC]
60
80
Figure 4.16. Typical TX Current Consumption vs. Temperature and Power Supply Voltage.
PA_CFG2 = 0x6B
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Application Note AN110
Figure 4.17. 20 dB Bandwidth, 50 kbps, PA_CFG2 = 0x6B. Measured According to FCC
15.247
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Application Note AN110
4.4.2
Duty Cycling
Section 15.209 gives the general limits for the emission of intentional or unintentional
radiators. Above 960 MHz the limit is -41.2 dBm (500 uV/m at 3 m distance). When operating
under Section 15.247 the spurious emission must be 20 dB below the carrier unless it falls
within one of the restricted bands defined in Section 15.205. When operating in the in the 902rd
th
th
th
928 MHz frequency range the 3 , 4 , 5 , and 6 harmonics fall within restricted bands. In the
restricted bands the general limits of -41.2 dBm apply.
Pulsed transmissions allow higher peak harmonic and spurious emissions above 1 GHz
because an averaging detector is called for in the measurements. The average limit must be
below -41.2 dBm, but maximum peak spurious level for pulsed transmission is 20 dB above
the average limit. If the duty cycle factor of the periodic signal is known, measuring the peak
value and adding a duty cycle relaxation factor determines the average value. The relaxation
factor applies to the TX on-time as measured over a 100 ms period. The relaxation factor is
20 log (TX on-time/100 ms) [dB].
As an example, a 50 % duty cycle allows for 6 dB higher peak emission than without duty
cycling. Figure 4.18 gives the relaxation factor for different transmission on-times over a 100
ms period.
If the TX on-time is above 100 ms duty cycle relaxation cannot be applied and the maximum
output power, when using the CC1120+CC1190 915 MHz reference design, is limited to
approximately +24 dBm (see Table 4.5).
10
Relaxation Factor (dB)
9
8
7
6
5
4
3
2
1
0
30
40
50
60
70
On-time (ms)
80
90
100
Figure 4.18. Relaxation Factor vs. Duty Cycling
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Application Note AN110
4.4.3
Typical TX Parameters vs. Load Impedance
The load impedance presented to the CC1190 PA output is critical to the TX performance of
the reference design. The load impedance is selected as a compromise between several
criteria, such as output power, efficiency and the level of the harmonics. The matching
components between the PA output and the antenna should transform 50 ohm antenna
impedance to the selected impedance which the CC1190 PA should see. This is taken care of
by the reference design and the user should provide a well matched antenna to get the
required performance.
In order to measure the performance under different mismatch conditions the CC1120CC1190EM 915 MHz reference design is loaded with different impedances at the SMA
connector reference plane. A well matched antenna will have impedance inside the black
circle in the Smith chart, which illustrates the limit for 10 dB return loss. At each load the
output power, current and spurious frequency components are measured. These
measurements are known as load-pull measurements.
Figure 4.19. Output Power (left) and Current (right) vs. Load Impedance at SMA
Connector at 25°C. PA_CFG2 = 0x77.
Most PAs have the ability to oscillate at unwanted frequencies under certain conditions. The
worst conditions are usually high output power, low temperatures, and high VDD. The
spurious frequency components are measured under different mismatch conditions as
illustrated in Figure 4.20 and Figure 4.21. The blue colors indicate that the spurious levels are
at the noise floor. The CC1120-CC1190EM 915 MHz reference design is a very robust design
which tolerates high mismatch ratios at high output power, low temperatures and high VDD.
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Application Note AN110
Figure 4.20. Spurious Frequency Components vs. Load Impedance at SMA Connector at
25°C. PA_CFG2 = 0x77.
Figure 4.21. Spurious Frequency Components vs. Load Impedance at SMA Connector at
-40°C. PA_CFG2 = 0x77.
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Application Note AN110
4.5
Measurement Equipment
The following equipment was used for the measurements.
Measurement
Instrument Type
RX
Signal Generator
TX
Signal Analyzer
Power Supply
Multimeter
Automatic Tuner
EMC chamber
RX/TX
Stability
Radiated spurious Emissions
Instrument Model
Rohde & Schwarz SMIQ 03B
Rohde & Schwarz FSEM30
Rohde & Schwarz FSG
Agilient E3631A
Keithley 2000
Maury MT986EU32
Table 4.6. Measurement Equipment
5
Controlling the CC1190
There are three digital control pins (PA_EN, LNA_EN, and HGM) that sets the CC1190 mode
of operation.
PA_EN
0
0
0
1
1
LNA_EN
0
1
1
0
0
HGM
X
0
1
0
1
Mode of Operation
Power Down
RX LGM
RX HGM
TX LGM
TX HGM
Table 5.1. CC1190 Control Logic
There are different ways of controlling the CC1190 mode of operation in a CC1120-CC1190
design.


3
Using CC1120 GPIO0/ GPIO2/ GPIO3 pins to set two of the CC1190 control signals
(e.g. PA_EN and LNA_EN). The third control signal (e.g. HGM) can be hardwired to
GND/VDD or connected to an external MCU.
Using an external MCU to control PA_EN, LNA_EN, and HGM.
Using an external MCU to set one (or more) digital control signals is the recommended
solution for a CC1120-CC1190 design since GPIO0 or GPIO2 are typically programmed to
provide a signal related to the CC1120 packet handler engine to the interfacing MCU and
GPIO1 is the same pin as the SO pin on the SPI interface. The GPIO pin not used to provide
information to the interfacing MCU can be used to control the CC1190.
6
SmartRF Studio and TrxEB
The CC1120-CC1190EM 915 MHz together with SmartRF™ Studio 7 software [6] and TrxEB
can be used to evaluate performance and functionality.
6.1
SmartRF Studio
The CC1120-CC1190 can be configured using the SmartRF Studio 7 software [6]. The
SmartRF Studio software is highly recommended for obtaining optimum register settings. A
screenshot of the SmartRF Studio user interface for CC1120-CC1190 is shown in Figure 6.1.
3
GPIO1 is not used since this is the same pin as the SO pin on the SPI interface. The output
programmed on this pin will only be valid when CSn is high. For a system where eWOR is
used the LNA_EN pin on the CC1190 should be controlled by GPIO3. This is related to the
polarity of the CC1120 GPIO pins in SLEEP.
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Application Note AN110
Figure 6.1. SmartRF Studio 7 [6] User Interface
In order to control the CC1190 the user needs to set GPIO2=0x33 and GPIO0=0x73 to set
CC1190 in TX and GPIO2=0x73 and GPIO0=0x33 to set CC1190 in RX.
6.2
TRxEB
If CC1120-CC1190 is used with the TrxEB and the USB controller the supply range is 3.0 V to
3.6 V.
7
Reference Design
The CC1120-CC1190EM 915 MHz reference design includes schematic and gerber files [4]. It
is highly recommended to follow the reference design for optimum performance. The
reference design also includes bill of materials with manufacturers and part numbers.
7.1
Power Decoupling
Proper power supply decoupling must be used for optimum performance. The capacitors C26,
C27 and C30 ensure good RF ground after L21 and thus prevent RF leakage into the power
supply lines causing oscillations. The power supply filtering consisting of C2, C3 and L2
ensure well defined impedance looking towards the power supply.
7.2
Input/ Output Matching and Filtering
The PA and the LNA of the CC1190 are single ended input/output. A balun is required to
transform the differential LNA input of the CC1120 to single ended output of the CC1190 PA.
The values of the matching components between the SAW filter and the CC1190 PA input are
chosen to present optimum source impedance to the CC1190 PA input with respect to
stability.
The CC1190 PA performance is highly dependent on the impedance presented at the output,
and the LNA performance is highly dependent on the impedance presented at the input. The
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Application Note AN110
impedance is defined by L21 and all components towards the antenna. These components
also ensure the required filtering of harmonics to pass regulatory requirements.
The layout and component values need to be copied exactly to obtain the same performance
as presented in this application note.
7.3
Bias Resistor
R141 is a bias resistor. The bias resistor is used to set an accurate bias current for internal
use in the CC1190.
7.4
SAW Filter
A SAW is recommended for the CC1120-CC1190 design to attenuate spurs below the carrier
frequency that will otherwise violate spurious emission limits under Section 15.209 and 15.205
The SAW filter is matched to the CC1190 PA input/LNA output impedance using a series
inductor and a shunt capacitor.
7.5
PCB Layout Considerations
The Texas Instruments reference design uses a 1.6 mm (0.062”) 4-layer PCB solution. Note
that the different layers have different thickness. It is recommended to follow the
recommendation given in the CC1120–CC1190EM 915 MHz reference design [4] to ensure
optimum performance.
The top layer is used for components and signal routing, and the open areas are filled with
metallization connected to ground using several vias. The areas under the two chips are used
for grounding and must be well connected to the ground plane with multiple vias. Footprint
recommendation for the CC1190 is given in the CC1190 datasheet [3].
Layer two is a complete ground plane and is not used for any routing. This is done to ensure
short return current paths. The low impedance of the ground plane prevents any unwanted
signal coupling between any of the nodes that are decoupled to it.
Layer three is a power plane. The power plane ensures low impedance traces at radio
frequencies and prevents unwanted radiation from power traces. Two different power planes
for CC1120 and CC1190 are used and they are surrounded by ground to reduce unwanted
radiation from the board.
Layer four is used for routing, and as for layer one, open areas are filled with metallization
connected to ground using several vias.
7.6
Shielding
RF shielding is necessary to keep the radiated harmonics below the regulatory limits.
SWRA387B
Page 21 of 22
Application Note AN110
8
Disclaimer
The CC1120-CC1190EM evaluation board is intended for use for ENGINEERING
DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES ONLY and is not
considered by TI to be a finished end-product fit for general consumer use. Persons handling
the product(s) must have electronics training and observe good engineering practice
standards. As such, the goods being provided are not intended to be complete in terms of
required design-, marketing-, and/or manufacturing-related protective considerations,
including product safety and environmental measures typically found in end products that
incorporate such semiconductor components or circuit boards. This evaluation board has
been tested against FCC Section 15.247, 15.209, and 15.205 regulations, but there has been
no formal compliance testing at an external test house. It is the end user's responsibility to
ensure that his system complies with applicable regulations.
9
References
[1] CC1120 Datasheet (SWRS112.pdf)
[2] CC1120 User Guide (SWRU295.pdf)
[3] CC1190 Datasheet (SWRS089.pdf)
[4] CC1120–CC1190EM 915 MHz Reference Design (SWRR089.zip)
[5] FCC rules (www.fcc.gov)
™
[6] SmartRF Studio 7 (SWRC176.zip)
10 General Information
10.1 Document History
Revision
SWRA387
SWRA387A
SWRA387B
Date
2011.11.03
2011.11.24
2013.06.13
Description/Changes
Initial release.
Changes to Chapter 5 (Controlling the CC1190)
Added CC120x to the list of devices
SWRA387B
Page 22 of 22
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