National Semiconductor Introduces Differential Amp and ADC Combo

At a frequency of 248 MHz, the ADC10D1000 provides the industry’s highest spurious-free dynamic range (SFDR) performance of 66 decibels relative to carrier (dBc) and 9.1 effective number of bits (ENOB). Running off a single supply voltage, the ADC10D1000 achieves this unparalleled level of performance while consuming 33 percent less total power (2.8W) than comparable ADCs. The 2.5 GHz LMH6554 wideband, fully differential amplifier drives the 10-bit ADC10D1000, providing best-in-class 0.1 dB gain flatness up to 800 MHz, SFDR of 72 dBc at 250 MHz and leading low-input voltage noise performance of 0.9 nV/sqrt Hz.

These devices feature power-to-performance metrics that position them among National’s PowerWise® family of energy-efficient products. The ADC10D1000 yields 2.52 picojoules (pJ) per conversion, while the LMH6554 consumes 21 uA per MHz.

The ADC10D1000’s industry-best SFDR and ENOB allow it to maintain excellent performance through the first, second and third Nyquist zones. This new performance level enables digitization of wide swaths of bandwidth in applications that have previously had to use narrowband ADCs to achieve high-resolution sampling. For example, high-resolution radar systems now can use fewer parallel channels to digitize the same bandwidth, enabling significantly reduced board size and power dissipation. The ADC10D1000’s extremely low 2.8W power consumption also enables system design without heat sinks over the -40 degrees C to 85 degrees C industrial temperature range, which saves space and weight.

The ADC10D1000 digitizes a pair of analog input signals at sampling rates up to 1 GSPS, or a single analog input signal at speeds up to 2 GSPS. Additional features include AutoSync for multi-chip synchronization and programmable gain and offset adjustment for each channel. The internal track-and-hold amplifier and the extended self-calibration scheme enable a very flat response of all dynamic parameters beyond Nyquist, while providing an exceptionally low 10 (-18) code error rate. The ADC10D1000 is supplied in a leaded or lead-free, 292-ball, thermally enhanced BGA package.

The LMH6554 is a 2.5 GHz fully differential amplifier that provides exceptional 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 75 MHz when driving 2V peak-to-peak into loads as low as 200-Ohms. 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 1.8 GHz, 8 dB noise figure and a slew rate of 6200 V/us.

The LMH6554 is manufactured on National’s new CBC8 silicon germanium (SiGe) complementary bipolar-CMOS process technology. Among the most advanced analog processes in the industry today, the CBC8 process features a unique, monolithic, combination of SiGe NPN and PNP transistors, as well as low power CMOS transistors that enable exceptional speed, linearity, circuit density, low power and low noise for demanding high speed analog applications. The LMH6554 operates over the extended temperature range of -40 degrees C to 125 degrees C and is supplied in a space-saving, thermally enhanced, 14-pin flip-chip on lead (FCOL) package.

A reference board that includes the ADC10D1000, LMX2531 clock source and a field-programmable gate array (FPGA) interfaces directly with National’s new WaveVision 5 software to simplify the evaluation process. The WaveVision 5 system is an easy-to-use analysis tool, designed to help users evaluate National’s signal path products. For example, the ADC10D1000 can be teamed with the LMH6554 amplifier as well as LMX2531 single-chip phase-locked loop (PLL) and voltage-controlled oscillator (VCO) or one of National’s LMK04000 family of clock jitter cleaners to form a complete signal path solution.