Out in Front: November 9, 1995
VLSI Technology’s new Geode two-chip set implements a Cellular Digital Packet Data (CDPD) modem and provides a reference design for telemetry and data-only mobile-end-system applications. The product works in wireless applications and those that use less-than-1-kbyte bursts of data.
The CDPD reference design departs from the traditional chip-set offering, in which you must integrate and test a predefined chip set in a design. Instead, VLSI has compiled and tested a complete modem, providing a platform on which to develop applications. The design includes development tools, on-site customer training, documentation, and technical support.
VLSI has tested the Geode CDPD protocol stack, including Transmission Control Protocol/Internet Protocol, User Datagram Protocol/Internet Protocol, and media-access-control (MAC) layers; radio resource-management software; and the encryption module.
The chip set comprises the 32-bit Ruby II Advanced RISC Machines µP and the Topaz mixed-signal CDPD radio-interface IC. Ruby II includes a set of communication peripherals and provides low-power, high-performance, and low-cost operation. The chip provides the communication elements connecting the host system, the interface chip, and the radio. Ruby II comes in a 176-pin TQFP.
Topaz serves as the physical-layer interface connecting the radio, the MAC layer, and the radio-resource-management software running on Ruby II. The Topaz chip provides a baseband interface to a CDPD-compatible radio. VLSI accomplishes this by integrating the analog-interface circuits and DSP functions on a mixed-signal CMOS IC.
The radio-interface IC provides interfaces with a variety of radios with an architecture employing direct VCO modulation on the transmission side and FM-signal discrimination on the receiving side. The interface chip has a µP interface for configuration, control, and status. The radio interface provides D/A and A/D converters for processing the receive-strength indicators and controlling other radio functions. The Topaz chip comes a 100-pin TQFP. Price of the two-chip set is $24.50 (10,000). —by John Gallant
VLSI Technology Inc, San Jose, CA. (408) 434-3000.