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National Semiconductor Introduces Three New High-Speed Amplifiers, Including Lowest-Noise 300MHz Dual Amp

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National Semiconductor announced three new LMH amplifier products for the high-speed analog market fabricated on Nationalıs industry-leading VIP10 manufacturing process. These products have improved AC performance, low noise, low power and large signal bandwidth for high-speed applications in video cameras, xDSL modems and set-top boxes. ıNational Semiconductor continues to create high-performance products for the high-speed amplifier market,ı said Jeff Hooker, marketing manager for Nationalıs amplifier product group. ıNationalıs LMH6628, LMH6715 and LMH6718 exceed all previous specifications, giving customers additional performance and making these amplifiers suitable for new, faster applications.ı LMH6628 Nationalıs LMH6628, voltage feedback amplifier is an improved, lower power version of the CLC428. It is the lowest-noise, 300MHz, 550V/usec slew rate, dual amplifier on the market. Its 2nV/ıHz noise figure makes it ideal for receiving small signals over long, twisted pair telephone lines such as VDSL applications. The fast settling time of 12ns to 0.1% and low THD of ı65dBc make it a good fit for 10-bit data acquisition systems. The ability to drive heavy capacitive loads also makes the LMH6628 suitable for directly driving analog-to-digital converters. This allows the elimination of an additional buffer stage in the front end of many receiver applications. LMH6715 Nationalıs LMH6715 current feedback dual video amplifier is a faster version of the CLC412. It has excellent key video specifications with differential gain and phase (DG/DP) of only 0.02 percent/0.02 degrees. The LMH6715ıs large signal, 3dB bandwidth of 170 MHz at Av=+2 for a 4V PP output and 0.1dB gain flatness to 100MHz make it well suited for high-end video systems. It is able to drive 8V PP from a 10V supply, an improvement over the CLC412ıs output dynamic range by over 1V. The improved AC parameters make the LMH6715 a good fit for many high-end consumer video applications such as video distribut ion systems, video cameras, video cable driving, multimedia systems and HDTV. LMH6718 Nationalıs LMH6718 dual programmable gain buffer (PGB) is an enhanced version of the CLC5632. It has an improved output stage and can deliver 50 percent more current (200mA) than the CLC5632 while consuming less quiescent power (2.6mA). The LMH6718 PGB incorporates the normally external Rf/Rg resistors on die, allowing it to easily be programmed to a gain of Av= -1, +1, +2 without external components. This feature lowers parts count and reduces layout area, but also shields sensitive input noise nodes that are typically exposed on the board. The output stage of the LMH6718 allows it to drive high capacitive, low resistive loads with minimum distortion (-85/-89dBc HD2/HD3, 2Vpp, 1MHz, RL=100 ohms at 5V) while maximizing output voltage swing. The LMH6718 provides 110MHz bandwidth (Av=+2V/V) and 400V/us slew rates on a single +5V supply and 130MHz-600V/us on dual +/-5V supplies. Specific applications targeted for the LMH6718 are dual, single-ended applications such as video line driving through coaxial cable and signal-boosting applications such as driving single-ended transformers for twisted pair. VIP10 Process Developed in National's wafer fabrication site in Arlington, Texas, VIP10 is a high-speed, dielectrically-isolated, complementary bipolar IC process that utilizes deep trench technology on a bonded wafer for complete dielectric isolation and optimal high-speed amplifier performance. Trench technology with bonded wafers helps minimize parasitic capacitance for optimal power-to-bandwidth performance, lower distortion and decreased die size. VIP10 is the process technology that allows National to design the most power-efficient, performance-oriented high-speed amplifiers on the market today. Nationalıs LMH6628, LMH6715 and LMH6718 were all developed using the VIP10 process and are the first replacement parts for the CLC amplifiers portfolio. Migration of other key CLC replacements will continue over the next year and be completed by June 2003. Design Support Group: (800) 272-9959 Website Click on the cross-reference chart to show the transfer of the most popular CLC operational amplifier devices to the new LMH amplifiers.

These three amplifiers from National Semi are upgrades from the older CLC models. For example, the LMH6715 is a faster version of the CLC412. The new LMH versions use Nationalıs VIP10 process. VIP stands for the vertically integrated NPN and PNP. The VIP10 is a complementary bi-polar process, which is a state of the art process that is also less expensive than the older process. VIP10 enabled National to design a part that consumes less current, and is less expensive. The VIP10 uses 0.15- micron complementary bipolar process ı much smaller than the process used for the CLC products. The market for these amplifiers is a very competitive arena so the new process helps the company keep at the top of the heap, and for the moment National has bragging rights to several best-of-class specs. For example, the LMH6628, which uses a voltage feedback topology is best in class because no one offers a 2nV/sq root Hz noise spec with 300MHz, gain of 1 bandwidth, and a 550 V/micro second slew rate. It is a dual voltage feedback part, and the selling feature is the ultra low noise and the high speed. It also provides a total harmonic distortion of ı65dBc. The release says the 2nV/sq root hertz spec is ideal for receiving small signals. This spec means that if you drive a signal over a cable for a long distance, you want it to have the least amount of noise so you can pick up the signal without adding any distortion. The 2nV/sq root hertz spec indicates the signal is very clean and free from distortion. The LMH6628 amp can be used for the residential broadcom marketplace, the telecom, and consumer electronics. It also works well in a VDSL receiver. Other higher noise parts can go in the more general consumer markets like ADSL, but VDSL and HDSL are a higher-grade DSL modem, and need a lower noise part like the 6628. The press release says that the 6628 is appropriate for 10-bit data acquisition systems. Specifically, the company is referring to an ADC driver or a DAC buffer. For those applications you want a fast settling time and fast pulse response. So the higher slew rate helps with the settling time. The fast settling time and fast pulse response is for the 8 to 12 bit ADC driver applications. For the DAC buffer application, itıs the high speed and fast settling time, while the low noise is less important. The LMH6715 is a dual video, current feedback amp for high-end video applications. For high-end video some of the key specs to look for are differential gain and differential phase. This National Semi part offers a very low 0.02 percent for differential gain and 0.02 degrees for differential phase. Typically, anything less than 0.1 is considered good, less than 0.05 exceptional. The 0.02 is actually at the limit that test instruments can detect, so those are some outstanding specs for high-end video. The 6715 also offers a slew rate of 1,300 V/us, has a unity gain small signal bandwidth of 600MHz, which equates to 0.1dB of gain flatness and a useable bandwidth of 100MHz, which is a very nice feature for video applications because they need about 0.1dB at 30MHz. For HDTV applications the requirements will go up to 0.1 dB at 50MHz. The 6715 will be used in various types of cable driving, digital video, buffers, line drivers in video systems, it could be professional grade, studio type quality or recording quality HDTV, used as a video line driver, line driver in a set top box, or video driver in an STB. Again, it fits 8- to 12-bit video ADC driver DAC buffer. For those applications, the low harmonics, as well as the low differential phase/gain and the high speed are the main reason these parts are successful. For the video line driving it will be successful because of the low differential phase/gain and the large signal bandwidth. The 6718 has a programmable gain buffer. The advantage with any programmable gain buffer is the elimination of external resistors, which means you donıt need gain and feedback resistors, because they are integrated. Depending on how you couple the input, you can set the gain at +1, -1, or a +2. Thatıs a nice feature for some designers, because it means you donıt have to use external components. The slew rate for the 6718 is 600V/us, and has a gain of 2. For most of the applications this part probably will be used for line driving, which only needs a gain of 1. The bandwidth for this part at a gain of 2, is 130MHz, output current is 130 mA. Some of the markets for these amps include residential broadband xDSL type line driving applications, cable drivers, video, STBs, portable test, instrumentation. The low-power, high-output current of the parts make it a good fit for communications applications such as those for a high-speed modem. The wide bandwidth, low differential gain/phase and low distortion make this a good match for cable driving applications. The LMH6628 is available now in 8-pin SOIC packaging, and is priced at $1.98. The LMH6715 is available in 8-pin SOIC packaging, and is priced at $1.69. The LMH6718 is available in 8-pin SOIC packaging and is priced at $1.88. All three product prices are for 1,000-unit quantities. Product brochures: LMH6628 LMH6715 LMH6718

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