TRC105 Datasheet, PDF (50/67 Pages) RF Monolithics, Inc – 300-510 MHz RF Transceiver

K = (F_CTX - 25)/25 = 11 for F_CTX = 300 kHz
For OOK operation, the receiver filters are configured as polyphase band-pass filters by setting RXCFG12 bit 7 to
1. The center frequency of the polyphase filters is set to 100 kHz to match the second IF frequency. The center
frequency, F_OPP, is configured with bits 7..4 in RXCFG11. For the standard crystal frequency of 12.8 MHz:
F_OPP = 200*(L + 1)/8, with L in the range of 0 to 15
Where F_OPP is the center frequency of the OOK polyphase filter in kHz, L is the integer value of the bit pattern in
RXCFG11 bits 7..4. The equation for determining L is:
L = (F_OPP - 25)/25 = 3 for F_OPP = 100 kHz
The recommended upper cutoff frequency for the receiver polyphase band-pass filters is:
F_CPP = F_OPP + BR
Where F_CPP is the upper cutoff frequency of the polyphase filters in kHz and BR is the bit rate in kb/s. This equa-
tion assumes use of the high accuracy, low drift XTL1020P crystal. If an alternative crystal is used, add ½ the ex-
pected drift due to temperature and aging to the equation above. F_CPP is configured with bits 3..0 in RXCFG10.
For the standard crystal frequency of 12.8 MHz:
F_CPP = 100 + 200*(J + 1)/8, with the usable range of J 0 to 1
Where F_CPP is the upper cutoff frequency of the receiver OOK polyphase filter in kHz and J is the integer value of
the bit pattern in RXCFG10 bits 3..0. The equation for determining J is:
J = (F_CPP - 125)/25
J must be an integer value, so F_CPP is limited to 2 discrete values: 125 kHz and 150 kHz. Choose the value of J
that provides the F_CCP value that is nearest to the value calculated for the bit rate you are using. The recommend-
ed 3 dB bandwidth for the receiver R-C filters is:
F_CRC = 3.25*F_CPP
Where F_CRC and F_CPP are in kHz. The bandwidth of F_CRC is set by bits 7..4 in RXCFG10. The relationship of the
R-C filter bandwidth to the integer value in RXCFG10 bits 7..4 is given in Table 61. The matching values for the
125 and 150 kHz F_CCP values are shown in bold:
Pattern of Bits 7..4
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
R-C Filter Bandwidth
65 kHz
82 kHz
109 kHz
137 kHz
157 kHz
184 kHz
211 kHz
234 kHz
262 kHz
321 kHz
378 kHz
414 kHz
458 kHz
514 kHz
676 kHz
987 kHz
Table 61
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TRC105 - 10/16/12