Single-Chip Low Power RF Transceiver for Narrowband Systems ...

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13.4. Reducing Spurious Emission and Modulation Bandwidth Modulation bandwidth and spurious emission are normally measured with the PA continuously on and a repeated test sequence. In cases where the modulation bandwidth and spurious emission are measured with the CC1021 switching from power down mode to TX mode, a PA ramping sequence could be used to minimize modulation bandwidth and spurious emission. 14. Input / Output Matching and Filtering When designing the impedance matching network for the CC1021 the circuit must be matched correctly at the harmonic frequencies as well as at the fundamental tone. A recommended matching network is shown in Figure 25. Component values for va Component value an be found using the SmartRF ® rious frequencies are given in Table 21. s for other frequencies c Studio software. CC1021 PA ramping should then be used both when switching the PA on and off. A linear PA ramping sequence can be used where register PA_POWER is changed from 00h to 0Fh and then from 50h to the register setting that gives the desired output power (e.g. F0h for +10 dBm output power at 433 MHz operation). The longer the time per PA ramping step the better, but setting the total PA ramping time equal to 2 bit periods is a good compromise between performance and PA ramping time. be measured and compared to the response of the Chipcon reference design. Refer to Figure 27 and Table 22 as well as Figure 28 and Table 23. The use of an external T/R switch reduces current consumption in TX for high output power levels and improves the sensitivity in RX. A recommended application circuit is available from the Chipcon web site (CC1020EMX). The external T/R switch As can be seen from Figure 25 and Table can be omitted in certain applications, but 21, the 433 MHz network utilizes a T-type performance will then be degraded. filter, while the 868/915 MHz network has a π-type filter topology. The match can also be tuned by a shunt capacitor array at the PA output It is important to reme mber that the (RF_OUT). The capacitance can be set in physical layout and the components used 0.4 pF steps and used either in RX mode contribute significantly to the reflection or TX mode. The RX_MATCH[3:0] and coefficient, especially at the higher TX_MATCH[3:0] bits in the MATCH harmonics. For this reason, the frequency register control the capacitor array. response of the matching network should Item 433 MHz 868 MHz 915 MHz C1 10 pF, 5%, NP0, 0402 47 pF, 5%, NP0, 0402 47 pF, 5%, NP0, 0402 C3 5.6 pF, 5%, NP0, 0402 10 pF, 5%, NP0, 0402 10 pF, 5%, NP0, 0402 C60 220 pF, 5%, NP0, 0402 220 pF, 5%, NP0, 0402 220 pF, 5%, NP0, 0402 C71 DNM 8.2 pF 5%, NP0, 0402 8.2 pF 5%, NP0, 0402 C72 4.7 pF, 5%, NP0, 0402 8.2 pF 5%, NP0, 0402 8.2 pF 5%, NP0, 0402 L1 33 nH, 5%, 0402 82 nH, 5%, 0402 82 nH, 5%, 0402 L2 22 nH, 5%, 0402 3.6 nH, 5%, 0402 3.6 nH, 5%, 0402 L70 47 nH, 5%, 0402 5.1 nH, 5%, 0402 5.1 nH, 5%, 0402 L71 39 nH, 5%, 0402 0 Ω resistor, 0402 0 Ω resistor, 0402 R10 82 Ω, 5%, 0402 82 Ω, 5%, 0402 82 Ω, 5%, 0402 Table 21. Component values for the matching network described in Figure 25. (DNM = Do Not Mount) SWRS045B Page 46 of 89
CC1021 CC1021 RF_OUT RF_IN C60 L1 AVDD=3V R10 L2 C3 C1 C7 1 C72 L70 L71 Figure 25. Input/output matching network Figure 26. Typical LNA input impedance, 200 – 1000 MHz CC1021 T/R SWITCH ANTENN ANTENNA A SWRS045B Page 47 of 89
Page 1 and 2: CC1021 CC1021 Single Chip Low Power
Page 3 and 4: CC1021 13. Transmitter ............
Page 5 and 6: 2. Absolute Maximum Ratings CC1021
Page 7 and 8: Parameter Spurious emission, radiat
Page 9 and 10: Input IP3 Parameter 433 MHz 102.4 k
Page 11 and 12: 4.3. RSSI / Carrier Sense Section P
Page 13 and 14: 4.6. Frequency Synthesizer Section
Page 15 and 16: 4.8. Current Consumption Parameter
Page 17 and 18: 6. Circuit Description RF_IN LNA RF
Page 19 and 20: Microcontroller configuration inter
Page 21 and 22: 8. Configuration Overview CC1021 ca
Page 23 and 24: 9.1. 4-wire Serial Configuration In
Page 25 and 26: 9.2. Signal Interface The CC1021 ca
Page 27 and 28: Transmitter side: DCLK DIO “RF”
Page 29 and 30: f ref f xosc = REF _ DIV + 1 FSK fr
Page 31 and 32: The DEC_DIV[2:0] bits in the FILTER
Page 33 and 34: 12.5. RSSI CC1021 has a built-in RS
Page 35 and 36: 12.6. Image Rejection Calibration F
Page 37 and 38: Blocker rejection [dB] 65 60 55 50
Page 39 and 40: • Frequency register setting is s
Page 41 and 42: 12.11. Carrier Sense The carrier se
Page 43 and 44: offset. The new frequency must be c
Page 45: Current [mA] / Output power [dBm] C
Page 49 and 50: 868 MHz CC1021 Figure 28: Typical o
Page 51 and 52: 15.2. VCO and PLL Self-Calibration
Page 53 and 54: CC1021 Loop C6 C7 C8 R2 R3 PLL turn
Page 55 and 56: Rese tCC102 0 WakeupCC1020ToRx/ Wak
Page 57 and 58: the "carrier sense" level (programm
Page 59 and 60: Item CL= 12 pF CL= 16 pF CL= 22 pF
Page 61 and 62: LNA_EN and PA_EN are used to contro
Page 63 and 64: frequencies is done through the MAI
Page 65 and 66: 26.1. CC1021 Register Overview CC10
Page 67 and 68: CC1021 INTERFACE Register (01h) REG
Page 69 and 70: CC1021 CLOCK_A Register (07h) REGIS
Page 71 and 72: CC1021 MODEM Register (0Dh) REGISTE
Page 73 and 74: CC1021 VGA1 Register (11h) REGISTER
Page 75 and 76: CC1021 VGA3 Register (13h) REGISTER
Page 77 and 78: CC1021 FRONTEND Register (16h) REGI
Page 79 and 80: BUFF_CURRENT Register (19h) REGISTE
Page 81 and 82: CC1021 TEST1 Register (21h, for tes
Page 83 and 84: CC1021 AFC Register (43h, read only
Page 85 and 86: 27. Package Description (QFN 32) CC
Page 87 and 88: 27.2. Recommended PCB Footprint for
Page 89 and 90: 29. General Information CC1021 Docu
Page 91: *All dimensions are nominal PACKAGE

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