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Signal path products for wideband applications

National Semiconductor has introduced a 2.5GHz differential amplifier and a 10-bit, 2GSPS single/1GSPS dual analogue-to-digital converter (ADC) that deliver dynamic system-level performance and low power for wideband applications. These combined signal path products are suitable for ground-based radar, data acquisition systems, point-to-point base stations and next-generation set-top boxes. At a frequency of 248MHz, the ADC10D1000 provides high SFDR (spurious-free dynamic range) performance of 66dB relative to carrier (dBc) and 9.1ENOB (effective number of bits). Running off a single supply voltage, the ADC achieves this performance with a less total power consumption of 2.8W. The 2.5GHz LMH6554 wideband, fully differential amplifier drives the 10-bit ADC10D1000 that provides 0.1dB gain flatness up to 800MHz, SFDR of 72dBc at 250MHz and low-input voltage noise performance of 0.9nV/√Hz. The ADC10D1000 yields 2.52pJ per conversion, while the LMH6554 consumes 21µA/MHz.

The ADC10D1000’s SFDR and ENOB allow it to maintain good performance through the first, second and third Nyquist zones. The ADC10D1000 has an advanced system design without heat sinks over the -40°C to 85°C industrial temperature range, which saves space and weight. It digitises a pair of analogue input signals at sampling rates up to 1GSPS, or a single analogue input signal at speeds up to 2GSPS. It also features AutoSync for multi-chip synchronisation and programmable gain and offset adjustment for each channel. The internal track-and-hold amplifier and the extended self-calibration scheme enable a flat response of all dynamic parameters beyond Nyquist, while providing a low 10-18 code error rate. The ADC10D1000 is supplied in a leaded or lead-free, 292-ball, thermally enhanced BGA package. A space-qualified version of the ADC10D1000 will be supplied in a hermetic 376 column, thermally enhanced, CCGA (ceramic column grid array) package. The space-level version meets radiation levels of 120MeV for single event latch-up and a total ionising dose of 300Krads, making it suitable for wideband satellite communications. Samples of the CCGA version are available now for evaluation.The LMH6554 amplifier provides signal fidelity for driving 8- to 16-bit high-speed ADCs. The device’s low impedance differential output is designed to drive ADC inputs and any intermediate filter stage. The LMH6554 delivers 16-bit linearity up to 75MHz when driving 2V peak-to-peak into loads as low as 200Ω. With external gain set resistors and integrated common-mode feedback, the LMH6554 can be used in differential-to-differential or single-ended-to-differential configurations. The amplifier provides large signal bandwidth up to 1.8GHz, 8dB noise figure and a slew rate of 6200V/µs. The LMH6554 is manufactured on National’s new CBC8 silicon germanium (SiGe) complementary bipolar-CMOS process technology. The CBC8 process features a monolithic combination of SiGe NPN and PNP transistors, as well as low power CMOS transistors that enable good linearity and circuit density, low power and low noise for demanding high speed analogue applications. The LMH6554 operates over the extended temperature range of -40°C to 125°C and is supplied in a space-saving, thermally enhanced, 14-pin FCOL (flip-chip on lead) package.