TRC105 RFM, TRC105 Datasheet - Page 8

• Manufacturer Part Number: TRC105
• Description: IC TXRX 300MHZ-510MHZ 32TQFN
• Manufacturer: RFM

Specifications of TRC105

• Frequency: 300MHz ~ 510MHz
• Data Rate - Maximum: 200kbps
• Modulation Or Protocol: FSK, OOK
• Applications: General Purpose
• Power - Output: 13dBm
• Sensitivity: -112dBm
• Voltage - Supply: 2.1 V ~ 3.6 V
• Current - Receiving: 3mA
• Current - Transmitting: 30mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-TQFN
• Wireless Frequency: 300 MHz to 510 MHz
• Output Power: 13 dBm
• Operating Supply Voltage: 2.1 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Maximum Supply Current: 1.7 mA
• Minimum Operating Temperature: - 40 C
• Modulation: FSK, OOK
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Memory Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 583-1159-2

OOK modulation is performed by switching on and off the power amplifier and its regulator. The rise and fall times
of the OOK signal can be configured in register MCFG05_PA_Ramp[7..6], which controls the charge and dis-
charge time of the regulator. Figure 4 shows the time constants set by MCFG05_PA_Ramp[7..6]. Table 2 gives
typical values of the rise and fall times as defined in Figure 4 when the capacitance connected to the output of the
regulator is 0.047 µF.
Figure 4
2.3 Receiver
The TRC105 is set to receive mode when MCFG00_Chip_Mode[7..5] is set to 011. The receiver is based on a
double-conversion architecture. The front-end is composed of an LNA and a mixer whose gains are constant. The
mixer down-converts the RF signal to an intermediate frequency which is equal to 1/8 of the LO frequency, which
in turn is equal to 8/9 of the RF frequency. Behind this first mixer there is a variable gain IF amplifier that can be
programmed from maximum gain to 13.5 dB less in 4.5 dB steps with the MCFG01_IF_Gain[1..0] register.
After the variable gain IF amplifier, the signal is down-converted into two I and Q base-band signals by two quad-
rature mixers which are fed by reference signals at 1/8 the LO frequency. These I and Q signals are then filtered
and amplified before demodulation. The first filter is a second-order passive R-C filter whose bandwidth can be
programmed to 16 values with the register RXCFG10_LP_filt[7..4]. The second filter can be configured as either
a third-order Butterworth active filter which acts as a low-pass filter for the zero-IF FSK configuration, or as a
polyphase band-pass filter for the low-IF OOK configuration. To select Butterworth low-pass filter operation, bit
RXCFG12_PolyFilt_En[7] is set to 0. The bandwidth of the Butterworth filter can be programmed to 16 values
with the register RXCFG10_BW_Filt[3..0]. The low-IF configuration must be used for OOK modulation. This con-
figuration is enabled when the bit RXCFG12_PolyFilt_En[7] is set to 1. The center frequency of the polyphase
filter can be programmed to 16 values with the register RXCFG11_PolyFilt[7..4]. The bandwidth of the filter can
be programmed with the register RXCFG10_BW_Filt[3..0]. In OOK mode, the value of the low-IF is equal to the
deviation frequency defined in register MCFG02_Freq_dev. In addition to channel filtering, the function of the
polyphase filter is to reject the image. Figure 5 below shows the two configurations of the second IF filter. In the
Butterworth configuration, F
is the 3 dB cutoff frequency. In the polyphase band-pass configuration F
is the
CBW
OPP
center frequency given by RXCFG11_PolyFilt[7..4], and F
is the upper 3 dB bandwidth of the filter whose off-
CPP
set, referenced to F
, is given by RXCFG10_BW_Filt[3..0].
OPP
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TRC105 - 11/01/10