2.4-GHz programmable differential amplifiers provide optimized noise and distortion performance over entire gain range

September 20, 2012 // By Paul Buckley
Texas Instruments Incorporated has introduced the first programmable differential amplifiers. The 2.4-GHz LMH6881 single-channel PDA and 2.4-GHz LMH6882 dual-channel PDA provide optimized noise, distortion and bandwidth performance over a 6-dB to 26-dB gain range.

Designing systems with PDAs increases flexibility and reduces design time, solution size and bill of materials (BOM) cost for a broad range of applications.

PDAs combine the best of fully-differential amplifiers (FDAs) and digital variable gain amplifiers (DVGAs). They allow engineers to easily modify their designs by changing gain without having to adjust external resistors, replace amplifiers, or reconfigure and optimize each gain stage. Compared to traditional DVGAs, TI’s PDAs offer more consistent noise and distortion performance over the entire gain range. The programmable gain control in the LMH6881 and LMH6882 eliminates the need for gain-setting resistors and their associated mismatch errors, enabling more robust systems for applications, such as medical, test and measurement, military, wireless communications, and microwave backhaul.

The LMH6881 and LMH6882 maintain excellent noise and distortion performance over the entire gain range. Specifications at maximum gain (26 dB) and 100-MHz input frequency are: 9.7-dB noise figure, 44-dBm OIP3, and -100 dBc HD3.

The devices’ Gain control can be implemented via SPI bus or dedicated pins, with no external resistors needed.  Support for DC/AC coupling and single-ended-to-differential conversion eliminates the need for a balun, giving designers the flexibility to operate from DC to high frequencies with minimal external components.

The LMH6882’s channel gain matching of 0.2 dB and phase matching of 1.5 degrees provide excellent image rejection for wideband zero IF and I/Q sampling applications.

TI offers a variety of tools and support to speed development with the LMH6881 and LMH6882 PDAs. Evaluation modules (EVMs), as well as TINA-TI SPICE models and reference designs, are available to quickly evaluate the devices and accelerate system development.

More information about the LMH6881 and LMH6882 PDAs at
www.ti.com/lmh688x-pr

More information about the TINA-TI SPICE models for the LMH6881 and LMH6882 PDAs at www.ti.com/lmh6881spice-pr and www.ti.com/lmh6882spice-pr