900MHz full-duplex wireless transmitter reference design

Figure 1. The reference design board uses the MAX2902 single-chip transmitter and is designed to operate in the 868MHz to 915MHz band. The device is fully compliant with FCC CFR47 Chapter 15.247 specifications for the 902MHz to 928MHz ISM band.

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Figure 2. MAX2902 900MHz BPSK transmitter reference design block diagram. This article provides the characteristic report (v1b), block diagram and interface connection. In order to reduce the coupling from the PA, the VCO and TCXO of the Tx IC adopt independent LDO powered. The second output of the LDO powers the synthesizer and Tx IC (except the PA). The transmitter's PA is powered directly from the system supply (V _{CC_MAIN} ). In addition, when the VSWR is 8:1, the PA requires the output power to be greater than 18dBm under the condition of meeting 20% ​​EVM. This 40MHz WLAN TCXO is used as a temporary replacement and was originally designed for the 16.36MHz GPS reference. The PLL is capable of accepting any reference clock frequency ranging from 1MHz to 50MHz. Customers should select the appropriate TCXO based on cost and phase noise tolerance of the carrier before modulation.