Microwave and RF engineers have become more familiar with data converters and digital signal processors (DSPs) in recent years. These components are now mainstays in many wireless systems, making possible the complex filtering and algorithms employed in digital modulation schemes and multichannel communications architectures. In essence, analog-to-digital converters (ADCs) sample analog input signals, digital-to-analog converters (DACs) generate complex modulated waveforms for signal transmission, and DSPs provide the sophisticated filtering and signal manipulation in between the two converter types.

The general trend for ADCs, DACs, and DSPs is one of increased processing power at lower power-consumption levels. The recently introduced (see Microwaves & RF, February 2003, p. 118) TMS320VC5501 and TMS320VC5502 DSPs from Texas Instruments (Dallas, TX, www.ti.com) have dual multiply-and-accumulate (MAC) cores and 300-MHz clock speeds for prices starting at $5. These LQPF-packaged devices consume only 200-mW power during normal operation.

The company also recently announced a series of new processors for Universal Mobile Telecommunications System (UMTS) applications, in accordance with the new Open Mobile Application Processor Interface (OMAPI) standard (which is comprised of a set of software interfaces to the operating system and a set of hardware intefaces defining common application peripheral devices). These OMAPI processors combine a DSP and a high-speed microcontroller on a single chip. Based on a 0.13-µm complementary-metal-oxide-semiconductor (CMOS) process, the OMAP1612 processor, for example, combines the company's TMS320C55x DSP core (capable of operation to 204 MHz) with an ARM926TEJ processor core (also capable of operation to 204 MHz). The OMAP1612 is available with 128 to 256 Mb of stacked mobile double-data-rate (DDR) synchronous-dynamic-random-access memory (SDRAM) to help reduce the size of cellular handsets and Personal Digital Assistants (PDAs) while also lending the processing power for wireless streaming-video and multimedia applications. The OMAP1612 offers a dedicated connection to the company's TNETW1130 wireless-local-area-network (WLAN) processor to simplify the interface with 54-Mb/s WLAN circuitry.

Texas Instruments recently established new standards in terms of processing speed with their 720-MHz models TMS320C6414, TMS320C6415, and TMS320C6416 DSPs. All three devices include 1 MB of on-chip memory with differences in peripheral support and inclusion of coprocessors (such as the integral Viterbi and Turbo coprocessors on the TMS320C6416). These high-speed DSPs are well suited for digital video, imaging, and wireless communications applications. (Note that more information on these three new devices is available by logging directly onto the company's website at www.ti.com/720mhzp.)

One of the earlier developers of DSP technology (as Lucent Technologies), Agere Systems (Allentown, PA, www.agere.com) entered the marketplace for dual-MAC DSPs with its model DSP16411. Operating at maximum clock rates to 285 MHz, the DSP is optimized for use with communications infrastructure equipment. In addition to its enhanced direct-memory-access (DMA) capabilities, the DSP features an on-chip programmable PLL clock synthesizer to eliminate the need for a high-speed clock input. It is designed for use with a single +3.3 VDC.

In addition to Motorola (Phoenix, AZ) as a supplier of DSPs, it should be noted that some suppliers of field-programmable gate arrays (FPGAs), including Altera Corp. (San Jose, CA) and Xilinx, Inc. (San Jose, CA), promote the use of their ICs for DSP functionality. For example, Altera's Stratix line of FPGAs includes the embedded memory, embedded processors, and DSP blocks needed for high-speed DSP. The Stratix devices can provide 16 × 16 multiply operations at 270 MHz, for example.

At the recent Wireless Systems Design Conference & Expo (San Jose, CA), Fujitsu Microelectronics (San Jose, CA) announced their model MB86064 dual 14-b DAC for generation of carrier signals in Global System for Mobile Communications (GSM), wireless-code-division-multiple-access (WCDMA), and UMTS systems (see figure). The 800-MSamples/s device supports the wide channel bandwidths of these emerging wireless systems. Fabricated with a 0.18-µm CMOS process, the presence of two DACs within a common package supports diversity-transmit or dual-transmit applications as well as high-speed test equipment.