National Semiconductor Corporation introduced a high-dynamic range 14-bit A/D converter optimized to simultaneously digitize multiple channels in wireless base station receivers. Operating at 52MSPS, the CLC5958 offers superior receiver sensitivity with a spurious-free dynamic range (SFDR) of 90dB and a signal-to-noise ratio (SNR) of 70dB at 20MHz. Base station designers can now reduce system size and cost by replacing multiple lower dynamic range ADCs with a single CLC5958. The part further helps to simplify system design by eliminating the need for expensive filters, mixers and amplifiers.

"The CLC5958's combination of resolution and speed is a major technical breakthrough, and National Semiconductor is the first company to put this type of part into volume production," said Kurt Rentel, marketing director for National's Data Conversion System Group. "Since ADCs are at the core of digital base station receivers, the device's excellent SNR and SFDR performance translates into overall superior system performance. In addition, base station receiver designers can now replace up to four single channel receiver chains using lower dynamic range ADCs with a single multi-carrier receiver chain using the CLC5958."

"Also, much of the signal processing that was done in the analog domain in older systems is now in the digital domain for greater programmability and flexibility. The CLC5958 enables production of a software radio and promises even higher levels of integration in the future."

The CLC5958 integrates a low-distortion track-and-hold amplifier and a 14-bit multi-stage quantizer on a single die. It is housed in a 48-pin chip-scale package (CSP) with excellent electrical characteristics and very low thermal resistance for space-constrained applications. The device operates from a single 5V power supply. Other features include differential analog inputs, low jitter differential clock inputs, an internal bandgap voltage reference and CMOS/TTL compatible outputs.

The CLC5958 joins other members of the CLC family of high-performance products for the cellular base station market. Recent additions include the CLC5526 variable gain amplifier, the CLC5956 12-bit/65MSPS A/D and the CLC5902 digital down converter.

The Comlinear guys -- and I still cannot think of them as real National employees -- are a bit late getting into this market with all the products they have been offering, but this converter is, by far, the most interesting to date. The company is certainly not alone in the field and the lead they take here -- by being in production with a 14-bit 52-Msample/s converter -- is probably going to be eclipsed by another manufacturer's part that is being touted as 14-bit 80 Msample/s but for which only a preliminary data sheet is available. That said, however, design-ins that are needed within the next 120 days will probably go for the National part. National needs to learn to quote input bandwidth for this sort of part, which I would guess at about 125 MHz.

Although the major market for this product will be in base station receivers it is important to realize that every evolution in this bits/speed direction makes the full software radio more possible. OEMs will certainly demand lower prices for that application but prices will inevitably come down with volume. The base station market is certainly less demanding in pricing areas but both specifications and reliability are crucial. Whether a 90-dB SFDR is enough for these uses can be argued both ways, ad infinitum.