Constant linearity tech boosts RF digital VGA performance

Article By : IDT

The F1455 family maintains high linearity over a wide gain control range, significantly improving Tx system performance.

A new range of digital variable gain amplifiers (VGAs) for radio frequency (RF) base stations is packed with constant linearity technology, which promises to improve system performance.

With the KLIN constant linearity technology, IDT's F1455 family of high-gain, high-linearity transmitter VGAs maintains a high 38dBm output third order intercept point (OIP3) for the first 12dB of gain control range, providing greater dynamic range for the system. The F1455 family of devices is ideally suited to drive power amplifiers in wireless base station transmitters.

IDT’s KLIN technology extends both OIP3 and output 1dB compression point (P1dBO) amplifier gain settings. This is particularly valuable in transmitter designs where the gain of the device is maintained within a normal gain setting window about 6dB below maximum gain.

“The F1455 family provides high-reliability, monolithic, QFN-packaged silicon solutions that deliver unique constant high linearity via our new KLIN innovation,” said Chris Stephens, general manager of IDT’s RF division. “These ICs, which replace lower-reliability GaAs-based MCMs, continue IDT’s trend of bringing innovative design technology to the markets we serve.”

__Figure 1:__ *F1455 block diagram (Source: IDT)*

F1455 features include Broadband 1400 MHz to 2300 MHz operation; 32dB flat, temperature invariant max gain; 4dB NF @ max gain (2000MHz); 23dBm P1dBO (constant for first 12dB of gain reduction); 38dBm OIP3 (constant for 12dB gain reduction); 29.5dB total gain control range, 0.5dB step; and SPI interface for gain control.

The family also features internal matching and biasing as well as high reliability MSL1 package with low thermal resistance and single 5V supply voltage.

The F1455 is available in a 6 x 6 mm 28-QFN package, and is sampling now to customers.