QAM Modem IC For Narrowband Applications

CML Microcircuits has launched the CMX7163 wireless data QAM modem IC designed to deliver high spectral efficiency QAM for narrowband applications including Scada and M2M systems. The CMX7163 provides 4/16/64-QAM baseboard modem functions in a single chip, replacing the current need for user-programmed DSP plus codec ICs. This development includes high dynamic range analogue signal capturing, digital baseband filters, auxiliary codecs, clock generator, and I/O functions, all designed to lower total bill-of-materials cost and chip count.

The high level of total integration reduces technical risk and time to market, according to CML Microcircuits. The device is a complete baseband modem system delivering high performance and high spectral efficiency QAM for narrowband applications. These include M2M systems over dedicated channels, digital software defined radio (SDR), high-speed wireless data and Scada systems.

The half-duplex device, which is suitable for 6.25kHz, 12.5kHz and 25kHz bandwidths, operates up to 96kbps in 25kHz bandwidths, featuring channel estimation and equalisation. The device is suitable for interfacing to superheterodyne receivers (for example, CMX992) or direct conversion designs (for example, CMX994) providing performance compatible with regulatory standards such as EN 301 166, EN 300 113 and EN 302 561. The transmitter interface is compatible with the CML Cartesian loop technology (CMX998). The device utilises CML's Firmasic component technology.

On-chip sub-systems are configured by a Function Image data file that is uploaded during device initialisation and defines the device's function and features set. The device's functions and features can be enhanced by subsequent Function Image releases, facilitating in-the-field upgrades. The CMX7163 logical interface provides addressable configuration parameters that ease host driver development. Selectable modulation, symbol rate and FEC suit a range of application requirements without hardware reconfiguration.

Features include: direct I/Q analogue inputs and outputs; automatic DC offset compensation; pulse shape filtering; a Ramdac capability for PA ramping control; and a C-Bus (SPI compatible) serial interface to host the microcontroller. Four auxiliary ADCs and DACs, two programmable system clock outputs, four GPIO and a separate C-Bus (SPI) interface to allow automated control of the radio section. Other features optimised for high-performance modems include carrier sensing, transmit burst timing and automated control of receiver AGC (when using CMX992 or CMX994).