Motore di ricerca datesheet componenti elettronici |
|
MRF89XA Scheda tecnica(PDF) 58 Page - Microchip Technology |
|
MRF89XA Scheda tecnica(HTML) 58 Page - Microchip Technology |
58 / 140 page MRF89XA DS70000622D-page 58 Preliminary 2010-2017 Microchip Technology Inc. TABLE 3-1: FREQUENCY BAND SETTING 3.2.6.1 Trimming the VCO Tank by Hardware and Software To ensure that the frequency band of operation is accurately addressed by the R, P, and S dividers of the synthesizer, it is necessary to ensure that the VCO is correctly centered. The MRF89XA built-in VCO trimming feature makes it easy and is controlled by the SPI interface. This tuning does not require any RF test equipment, and can be achieved by measuring Vtune, which is the voltage between the PLLN and PLLP pins (6 and 7 pins). The VCO is centered if the voltage is within the range of 50 Vtune(mV) 150. This measurement should be conducted when in Transmit mode at the center frequency (fo) of the desired band (for example, approximately 867 MHz in the 863-870 MHz band), with the appropriate frequency band setting using the (FBS<1:0> bits (GCONREG<4:3>). If this inequality is not satisfied, adjust the VCOT<1:0> bits (GCONREG<2:0>) from ‘00’ by monitoring Vtune. This allows the VCO voltage to be trimmed in +60 mV increments. If the desired voltage range is inaccessible, the voltage may be adjusted further by changing the tank circuit inductance value. An increase in inductance results in an increased Vtune. In addition, for mass production, the VCO capacitance is piece-to-piece dependent. As such, the optimization proposed above should be verified on several prototypes, to ensure that the population is centered with 100 mV. The register associated with VCO is GCONREG (Register 2-1). 3.2.7 FREQUENCY CALCULATION As illustrated in Figure 2-5, the PLL structure com- prises three different dividers, R, P, and S, which set the output frequency through the LO. A second set of dividers is also available to allow rapid switching between a pair of frequencies: R1/P1/S1 and R2/P2/ S2. These six dividers are programmed by six indepen- dent registers (see Register 2-7 through Register 2- 12), which are selected by GCONREG. 3.2.8 FSK MODE The formula provided in Equation 3-1 gives the relationship between the local oscillator and R, P, and S values when using FSK modulation. EQUATION 3-1: 3.2.9 FSK MODE REGISTERS The registers associated with FSK mode are: • GCONREG (Register 2-1) •DMODREG (Register 2-2) 3.2.10 OOK MODE Due to the manner in which the baseband OOK symbols are generated, the signal is always offset by the FSK frequency deviation (FDVAL<7:0> as programmed in FDEVREG<7:0>). Therefore, the center of the transmitted OOK signal is represented by Equation 3-2. EQUATION 3-2: Consequently, in Receive mode, due to the low intermediate frequency (Low-IF) architecture of the MRF89XA, the frequency should be configured so as to ensure the correct low-IF receiver baseband center frequency, IF2, as shown in Equation 3-3. EQUATION 3-3: As described in Section 3.4.4, Channel Filters, it is recommended that IF2 be set to 100 kHz. 3.2.11 OOK MODE REGISTERS The registers associated with OOK mode are: • GCONREG (Register 2-1) •DMODREG (Register 2-2) •FLTHREG (Register 2-5) • OOKCREG (Register 2-22) Target Channel (MHz) FBS1 FBS0 863-870 1 0 902-915 0 0 915-928 0 1 950-960 1 0 frf fsk 9 8 ---f lo = frf fsk 9 8 --- fxtaL R 1 + ------------- 75 P 1 + S + = frf ook tx 9 8 --- fxtaL R 1 + ------------- 75 P 1 + S + f dev – = frf ook tx 9 8 --- f lo fdev – = frf ook rx 9 8 --- f lo IF2 – = frf ook rx 9 8 --- fxtaL R 1 + ------------- 75 P 1 + S + IF2 – = |
Codice articolo simile - MRF89XA |
|
Descrizione simile - MRF89XA |
|
|
Link URL |
Privacy Policy |
ALLDATASHEETIT.COM |
Lei ha avuto il aiuto da alldatasheet? [ DONATE ] |
Di alldatasheet | Richest di pubblicita | contatti | Privacy Policy | scambio Link | Ricerca produttore All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |