DALLAS Texas Instruments Inc. has launched a line of fully differential operational amplifiers that are intended to optimize the performance of high-speed analog-to-digital converters in digital signal processing applications.
Gary Reichmuth, strategic marketing manager for precision analog products, said one of the new parts can replace three conventional op amps and eliminate the need for precisely matched resistors.
"This reduces or eliminates the considerable analog expertise a system designer needs to devise a front-end to the A/D," Reichmuth said. "The THS41XX family provides a differential signal path from input to output, which results in better signal quality." Signal quality is important in high-speed communications applications that demand low bit-error rates.
The balanced, differential outputs of the new op amps effectively block most common-mode noise and give the devices total harmonic distortion as low as -83 decibels at 1 MHz. The first op amps in the family, the THS4141 and THS4131, have a top bandwidth of 160 MHz and 150 MHz respectively, and slew rates of 450 volts/microsecond and 51 V/microseconds, respectively. The power-supply range for both is from 5 to 15 volts.
Reichmuth said the op amps feature an output common-mode voltage pin that can be used to set output voltage. The pin is useful when THS41XX devices interface to a high-resolution A/D, because the op amp can use a reference voltage from the A/D to set an optimum output level. Designers can also use this pin for voltage-level shifting.
The THS41XX op amps include a power shutdown mode for low-power applications. The parts move into shutdown mode when they are not in use, and once there they draw as little as 860 microamps of supply current.
The THS41XX family is manufactured on TI's proprietary BiCom-I complementary bipolar process technology. The parts come in 8-pin small-outline integrated circuit packages or TI's "PowerPad" MSOP. The THS4141 is priced at $3.25 and the THS4131 at $3.35 in 1,000-piece quantities.
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EETInfo No. 601