WE2408 View Datasheet(PDF) - Unspecified
Part Name
Description
MFG CO.
'WE2408' PDF : 36 Pages View PDF
WiNEDGE & WiRELESS
Winceiver WE2408
2.4GHz Single Chip FM Transceiver
B. Gm baseband filter
On-chip baseband filter bandwidth is adjusted by choice of the external resistor between VDDA and
BBSET. Choose this resistor to give a same bandwidth as above.
R = 29kΩ x (65kHz/BWbb)
E.G., for 150kHz (r75kHz) bandwidth, BWbb=75kHz, suggested value is 24kΩ.
C. DC Offset Correction Loop (Effective Baseband High Pass Filter)
The 3dB bandwidth is set to ±100Hz by the external 330nF capacitors connected to DCI and DCQ.
The HP cut off can be adjusted by inverse proportional change in DCI/DCQ capacitor. For example, in
digital application, if the lowest data rate is 2400bps (1.2kHz), the cut off can be increased from
100Hz to 1kHz by reducing the capacitance to 33nF.
Reduction in the cut off lower than 100Hz, with BWdm=130kHz may lead to instability in Auto Gain
Control mode.
Common
Rx BW
150 kHz
100 kHz
50 kHz
25 kHz
BWbb
75 kHz
50 kHz
25 kHz
12.5 kHz
IFIL2/QFIL2
Cap /nF
1.5
2.2
4.7
9.1
IFIL3/QFIL3
Cap /nF
0.56
0.82
1.80
3.30
BBSET
R /kΩ
24
39
75
150
DEMODULATOR BANDWIDTH
Demodulator bandwidth, BWdm, is adjusted by the choice of the Period to Digital demodulator clock
frequency, Fpd. The chip divides down the receiver local oscillator, Frf, by 3 times the divide ratio,
PDR, to obtain Fpd.
Fpd = Frf / (3*PDR)
PDR is programmed by bits 14, 15 & 16 of the reference frequency register.
Allowable PDR values for WE2408 are 9, 12, 24, 36, 48, 72, and 96.
The choice of Fpd directly sets the IF frequency Fif, and BWdm:
Fif = Fpd/544
BWdm = Fpd/580
Choose a value of PDR to give BWdm > 2 x BWbb.
© 2003 WiNEDGE & WiRELESS PTE LTD
Rev Date: 2003 May 23
Page 16
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