CC26xx RF Frontends and Antenna

CC26xx HW Training
RF Front End options and Antennas
Fredrik Kervel, Bluetooth Smart Applications
1
Reference Schematic
VDD_EB
VDDS Decoupling Capacitors
VDDS
Pin 11
Pin 28
C2
C3
C4
C6
C7
DNM
100nF
100nF
10uF
100nF
BLM18HE152SN1
2
1
FL1
Pin 18
DCDC_SW2
VDDS
VDDS
R1
100k
6
DIO_0
7
DIO_1
8
DIO_2
9
DIO_3
10
DIO_4
15
DIO_5/JTAG_TDO
DIO_6/JTAG_TDI16
20
DIO_7
21
DIO_8
22
DIO_9
23
DIO_10
24
DIO_11
25
DIO_12
26
DIO_13
27
DIO_14
nRESET
JTAG_TCK
JTAG_TMS
C20
100nF
19
14
13
12
C19
1uF
33
U1
DIO_0
DIO_1
DIO_2
DIO_3
DIO_4
DIO_5
DIO_6
DIO_7
DIO_8
DIO_9
DIO_10
DIO_11
DIO_12
DIO_13
DIO_14
RESET_N
JTAG_TCKC
JTAG_TMSC
VDDR
VDDS
VDDS2
VDDS_DCDC
VDDR
VDDR
DCDC_SW
RX_TX
RF_N
RF_P
X24M_P
X24M_N
X32K_Q2
X32K_Q1
L1
10uH
Place L1 and
C8 close to pin 17
10uF
100nF
C10
C16
100nF
DNM
C31
17 DCDC_SW
L21
2.4nH
3
2
1
RFN
6.8pF
A1
C21
1
2
1
1pF
1
L10
6.8nH
X24M_P
X24M_N
RFP
5
4
2
C11
VSS
CC2650F128RHB
1
L11
2.4nH
2
L12
2
1
C12 2nH
C13
DNM
1pF
L13
2nH
2
C14
R12
12pF
0
3
1
C15
2.4GHz
DNM
R12 and C15 for
antenna matching
Y2
24MHz
Y1
1
32.768kHz
Pin 32
2
DCOUPL
12pF
C9
RX_TX
1pF
C17
C8
VDDR
28
11
18
29
32
31
30
VDDR Decoupling Capacitors
Pin 29
1
3
C18
12pF
2
4
2
RF pins
RF_P: RF positive output / input
RF_N: RF negative output / input
RX_TX: Optional RF bias pin
Several options on output configuration:
6
7
8
9
10
15
16
20
21
22
23
24
25
26
27
19
14
13
12
33
U1
DIO_0
DIO_1
DIO_2
DIO_3
DIO_4
DIO_5
DIO_6
DIO_7
DIO_8
DIO_9
DIO_10
DIO_11
DIO_12
DIO_13
DIO_14
RESET_N
JTAG_TCKC
JTAG_TMSC
DCOUPL
VSS
VDDS
VDDS2
VDDS_DCDC
VDDR
VDDR
DCDC_SW
RX_TX
RF_N
RF_P
X24M_P
X24M_N
X32K_Q2
X32K_Q1
28
11
18
29
32
17
3
2
1
31
30
-
Differential output: Both RF pins are used and a balun + a pi-filter is
required between the CC26xx and the antenna
-
Single ended output: Only one of the RF pins is used for RF output.
Only a pi-filter is required between the CC26xx and the antenna. Output
power is reduced and sensitivity is degraded
-
External biasing of the RF pins can be applied through the RX_TX pin.
This will improve sensitivity, but requires an additional inductor.
-
For single ended configuration, the unused RF pin may alternatively be
used as bias pin
-
RX_TX can be used for external control of for example an RF switch
RX_TX
RFN
RFP
5
4
CC26xx-5x5
Note:
-
The CC26xx 7x7 package does not have RX_TX-pin, while the CC13xx
7x7 package does.
3
RF Frontend options
External bias
- BLE:
1
6.8pF
L21
2.4nH
RX_TX
RFN
RFP
Sensitivity:
Sensitivity:
C31
1
1
1pF
L10
6.2nH
2
1
L11
1
L12
2
2nH
2
2
C13 2nH
C14
ANT
RF_N
RF_P
12pF
1pF
2.7nH
C11
1
L13
-96 dBm
- Zigbee: -97 dBm
- Zigbee: -100 dBm
C21
2
- BLE:
-97 dBm
L21
15nH
2
1
L12
C14
2
ANT
C12 2nH
C13
1.2pF
1.2pF
12pF
1pF
Sensitivity:
Sensitivity:
Internal bias
C31
- BLE:
1
6.8pF
L21
2.4nH
RFN
RFP
1pF
1
C11
L11
1
2
L12
2
2nH
2.7nH
1
L13
C13 2nH
1pF
2
C14
ANT
12pF
-94 dBm
- Zigbee: -95 dBm
- Zigbee: -99 dBm
C21
2
- BLE:
-96 dBm
RF_P
1
L12
C14
2
ANT
C12 2nH
C13
1.2pF
1.2pF
12pF
1pF
Pout_max = 5 dBm
Differential output
Pout_max = 2 dBm
Single-ended output
4
RF Frontend options
Differential
Single Ended
Ext. Bias Int. Bias Ext. Bias Int. Bias
Output Power
5
5
2
2
[dBm]
BLE Sensitivity
-97
-96
-96
-94
[dBm]
Zigbee Sensitivity
-100
-99
-97
-95
[dBm]
Inductors
5
4
2
1
Capacitors
5
5
3
3
10
9
5
4
5
Antennas for 2.4 GHz
• PCB antennas
–
–
–
–
DN007
Low (no) cost
Simple to integrate (follow the reference design )
Good performance
TI reference design for two different sizes which typically fits within
customer requirements (board space), DN007 and AN043
– Application Notes:
• DN007: http://www.ti.com/litv/pdf/swru120b
• AN043: http://www.ti.com/litv/pdf/swra117d
• Antenna selection guide: http://www.ti.com/litv/pdf/swra161b
• Chip antennas
–
–
–
–
AN043
Can be used in applications where size is critical
Performance is comparable to PCB antennas (depending on size)
Cost is (obviously) higher
Contact antenna manufacturer for recommendations
• Johanson, TDK, etc.
• Antenna tuning
– Required for both PCB- and chip antennas
– Can be don with matching network.....
– ..... or Antenna length (PCB antennas)
6
Available reference designs
• CC2650EM-7ID (7x7, Internal bias, Differential output)
• CC2650EM-5XD (5x5, External bias, Differential output)
• CC2650EM-4XS (4x4, External bias, Single ended output)
• CC2650EM-Murbal (5x5, Internal bias, Integrated balun)
7
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