Sundance SMT911 - Manual (Page 9)

SMT911 User Manual SMT911 Last Edited: 01/06/2010 10:09:00
The SMT911 is an advanced, high-quality MIMO transceiver card, designed to cover
all features of future high-speed MIMO radio systems. It is used in combination with
Sundance base modules such as the SMT351T.
On the SMT911 transceiver card, two single-chip MIMO RF front-ends (SE2545A23)
are applied, containing nearly all circuitry required between the transceiver and the
antenna. Two transceiver chips of type MAXIM MAX2829 are used to up and down-
convert signals between the WLAN carrier bands and the base-band. The MAX2829
is specially designed for MIMO/Smart Antenna application and the IEEE 802.11a/g
standard.
In order to fulfill the requirements of more simple and clever MIMO solutions, the
SMT911 transceiver card is equipped with two built-in ADC/DAC chips from Analog
Devices – AD9863. Each of the transceiver (MAXIM) chips is served by one AD9863.
The AD9863 integrates dual 12-bit ADCs and dual 12-bit DACs. The dual DACs
convert the digital base band I/Q signals to analog signals when the SMT911 card
acts as a transmitter. When the SMT911 card acts as receiver, the dual ADCs convert
the analog base-band I/Q
signals into a digital format for the FPGA base board. Two
additional ADC‟s (AD7476) are provided to enable conversion of the Receive Signal
Strength Information (RSSI) from the MAXIM transceivers. All control pins of the
mentioned ICs above are routed through to the base module via the QSH connector. The
firmware on the base module offers the user flexibility to specify control signals and
control register settings. More details about the firmware are explained in the Firmware
implementation section.
The SMT911 card has two external reference clock inputs. These external clock inputs
provide the reference for generating the sampling clock in both ADC/DAC chips, and
provide the transceiver PLL‟s a reference for creating the required 2.4GHz or 5GHz
carrier frequency. Both of these circuits can be run for wider synchronization from
these connectors, or from a fixed, on-board oscillator output of 40MHz. The maximum
clocking speed of the internal ADC‟s is 50MHz, and the maximum clocking speed of the
internal DAC‟s is 200MHz (attainable through internal PLL multiplying).