CMX990 GMSK Packet-Modem
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CML Microcircuits COMMUNICATION SEMICONDUCTORS GMSK Packet-Data Modem with RF Transceiver Flexible Packet and Freeformat Data Modes Baseband, IF and RF Integration 4 to 16 kbps GMSK Modulation Tx BT = 0.27, 0.3 or 0.5 Rx BT = 0.56 Integrated RF, IF and Synthesiser Sections - 400MHz to 1GHz Range - Dual Integer-N Synthesisers Full-Feature Airlink Frame Formatting - FEC, CRC, Interleaving and Scrambling Simple Parallel Host Interface Versatile System Clocks On-Chip ADCs and DACs for System Control and General Purpose Monitoring Suitable for EN 300 113, FCC CFR 47 Part 90 and Mobitex Applications Low-Power Operation with Dynamic Powersave Powersaving No-Leads 64 VQFN Q1 Package Demonstration and Evaluation Kits GLOBAL APPLICATIONS - Flow Metering - Vehicle Registration and Tracking - Trafc Congestion Reporting - Alarms - EPOS and ATM - Two-Way Paging - Emergency Services - Leisure and Gaming Functions - Domestic Control and Monitoring - Asset Management and Tracking - Public Transport Reporting - Mobitex Systems -

A single-chip GMSK packet-data modem and RF transceiver, the CMX990 provides the majority of circuits and functions, including host µC interfaces, to implement a full-feature ‘wireless modem’ sub-system. The CMX990 can operate in RF ranges of 400MHz to 1GHz at data rates of 4 to 16 kb/s, and is fully Mobitex compatible. Half-Duplex GMSK Modem Packet and Freeformat Capabilities Full Mobitex Compatibility IF, RF, Control and Synthesiser Stages The versatile GMSK modem is congured for either packet or freeformat data operation via an efcient task-oriented Rx and Tx format and command...

Operational Functions PA Temp Reverse Power Forward Power measure forward power measure reverse power ADC and DAC (auxiliary functions) TCXO Temp LO Clock TXCO Control Reference Dividers Forward Power Auxiliary ADCs and DACs Internal Control, Communication and Data Bus Baseband Clocks I Channel Select and Image Reject Digital Channel Filter Offset Control Level Track Data Buffer F SYNC Detect Frequency Measurement AGC with Gain Control Demodulator Digital Channel Filter Frame Header GMSK Baseband Modem Offset Control Frame Disassembly Frame Assembly Reverse Power Interfaces, Registers and...

The Baseband Modem The CMX990 can be employed, half-duplex, under the control of the host processor, as either a packet data or freeformat modem, to operate to many custom or proprietary systems, including to the Mobitex standard. Half-Duplex Modem Option Variable Bit-Rate Programming Task-Oriented ‘Congure-then-Task’ Logical Control Interface Packet or Freeformat Modes The diagram (right) shows an over-air packet signalling format. The format in the illustration describes a Mobitex specication transaction, but a similar format, employing a Frame Head and/or Data Blocks can also be used in...

The Baseband Modem . . . . . . Task Oriented Commands are available to provide simplicity and efciency to the conguration and operation of the modem. These are used as short-form instructions to the modem and are initiated when the host µC writes a relevant task to the CMX990’s Command Register. In the case of packet formats: frame heads, syncs, and data blocks can simply be dealt with by loading a sequence of tasks to the Command Register and by loading/reading the relevant ‘data’ to/from the Data Buffer. Data Operations Typical Task-Driven Tx Packet Format Transmit Data Block or...

Half-Duplex Operation Rx IF Gain Control with AGC User-programmed PA Power Ramping via Auxilliary DAC The CMX990, a broadband RF modem system, provides the majority of RF and IF functions, in both Tx and Rx paths, to form a complete half-duplex data transceiver whose RF system can support transmission and reception of data, in the range between 400MHz and 1GHz. Separate Rx Input for External IF Path The Transmitter takes the baseband I and Q signals from the modem and up-converts it, via a quadrature modulator, to a suitable Intermediate Frequency (IF). An offset PLL is used to control an...

Frequency and Control To the programmer the CMX990 appears as a series of addressable read and write registers via a simple parallel interface. To ease host µC loads, baseband data-pump functions are dealt with using direct shortform task oriented commands. All functions within the device can be directly addressed using Address, Control (IRQ, Read/Write, ChipSelect) and Data ports. Tx or Rx data is transferred to and from the host via a dedicated 18-byte read/write data buffer. Host Interfacing PA Temp ADCs and DACs are utilised for control and monitoring Control and Interface Functions...

Versatile On-chip Power Facilities Demonstration and Evaluation Kits for the CMX990 To speed-up the design-in of the CMX990 and to allow designers full access to all functions of the chip and its external components, two separate full-feature kits are available: the EV9900 and the EV9902. With a very low-power requirement, the majority of the on-chip functions of the CMX990 can be separately powersaved under host control. This enables minimum power consumption at all times. Each EvKit will allow the designer to experiment, evaluate and investigate the operations and features of a full...