National Semiconductor Corporation announced a new family of high speed LMH operational amplifiers that are designed for use in communications applications such as xDSL, set-top boxes and other consumer applications. The first eight products in the LMH series are based on a cutting-edge manufacturing process, known as VIP10 , that National has developed to produce high-speed amplifiers.

"National Semiconductor is a leader in operational amplifier innovation. We are continuing to drive the market by developing process technology that will allow us to cost-effectively produce high speed operational amplifiers with the lowest power consumption for a given bandwidth," said Suneil Parulekar, vice president of Nationalýs operational amplifier product line. "The eight products we are introducing today for the communications market are just the first offerings from the LMH family. The benefits of VIP10 will allow National to move into optical storage and video markets, further increasing our presence in the lucrative operational amplifier arena."

LMH Product Offerings

Nationalýs LMH66xx family of operational amplifiers is a new series of high speed products based upon the VIP10 process. The first members of the LMH66xx family consist of eight devices, each targeting a specific market segment within the communications market. National plans to introduce its second wave of LMH products, targeted for optical storage/video applications, in Q4 2001.

The LMH6672 is a dual high speed amplifier with a high output current of +320mA, a very low distortion rate of ý84dBc, and a good bandwidth-to-power ratio of 200MHz/5.5mA. Applications for the LMH6672 include Customer Premises Equipment (CPE) line drivers for xDSL applications.

Nationalýs LMH6654/55 high speed amplifiers have very low distortion and noise (4.5nV/rtHz), a good bandwidth-to-power ratio of 240MHz/4.5mA, and a high output drive of 110mA. Applications for the LMH6654/55 include Central Office (CO) and CPE receivers for xDSL applications.

The LMH6642/43 are cost-effective high speed amplifiers (130MHz) with excellent supply/output current ratio of 2.4mA/+90mA, rail-to-rail output, and true single supply voltage capability of 3.0-12V. Applications for the LMH6642/43 include cable set-top boxes, contact image scanners (CIS) and PC servers.

This is as much a process announcement as a product announcement, although this first series of new LMH products allows National a chance to catch up in some arenas. The most noticeable feature of the series is the pricing, which is extremely aggressive. In performance terms there are a mishmash of specs which are better than some products out there, and worse than others. Looking, for example, at the LMH6654 (which is my favorite here) the supply current for a 250-MHz op amp (data sheet number is 250) is really good, but why is the slew rate only 200 V/us? The low noise that is touted is measured at 100 kHz instead of the more normal 10 kHz and is not particularly low anyway. Other 250-MHz amps show input voltage noise at less than 2 nV/rtHz (with a couple coming in at 1.3.) The noise of the LMH6654 (adjusted to 10 kHz) is about 5.5 nV/rtHz.

Those things said this is a catch up that National has badly needed to keep it in contention for the really huge markets that are out there. In many cases the company will win sockets not by having the product that is on the edge of performance but because of the pricing. The company should also tout the low differential gains and phases of the products and other associated linearity improvements, some of which seem to put other processes to shame. VIP10 is a long way from the original VIP1 of 1986 with an npn Ft of just 400 MHz and 15-um dimensions. The new double-poly process gives an Ft of 9 GHz for an npn and 8 GHz for a pnp with 1-um dimensions; it is a silicon-on-insulator fabrication in the active area with the collectors fully dielectrically isolated.