Temperature-compensating attenuators deliver high linearity

November 29, 2011 // By Jean-Pierre Joosting
The RFSA4013 and RFSA4023 from RFMD are fully monolithic analog Temperature-Compensating Attenuators (TCAs) featuring exceptional linearity over their entire gain control range. These TCAs are designed to offset the gain reduction of an RF component over temperature without the need for closed loop feedback.

Three customer selectable temperature coefficients make these TCAs a flexible solution for RF lineups. Each attenuator incorporates revolutionary circuit architecture that solves a longstanding industry problem with regards to attenuator architecture: high IP3, low DC current, and broad bandwidth.

Traditional approaches for linear temperature-compensating devices require expensive co-fired ceramics with temperature-sensitive materials or current-hungry PIN diodes with elaborate area consuming control circuits. The RFSA4013 and RFSA4023 only require a single supply voltage and two logic bits to set the control attenuation slope versus temperature.

Click image for larger version.

Each TCA draws a low 1 mA current and is packaged in a small 3-mm x 3-mm QFN. These attenuators are internally matched to 50 Ω over their rated control range and frequency.

The TCAs cover a broadband 50 MHz to 4000 MHz frequency range with three selectable attenuation slopes versus temperature, IIP3 of +55 dBm, IIP2 of +85 dBm, and P1dB of over +30 dBm. Typical applications include cellular and 3G infrastructure, WiBro, WiMax, LTE, microwave radio and high-linearity level control.

For further information: www.rfmd.com.