The HMC985A is an absorptive Voltage Variable Attenuator (VVA) which operates from 20 - 50 GH z and is ideal in designs where an analog DC control signal must be used to control RF signal levels over a 35 dB dynamic range. It features two shunt-type attenuators which are controlled by two analog voltages, Vctrl1 and Vctrl2. Optimum linearity performance of the attenuator is achieved by first varying Vctrl1 of the first attenuation stage from -5V to 0V with Vctrl2 fixed at -5V. The control voltage of the second attenuation stage, Vctrl2, should then be varied from -5V to 0V with Vctrl1 fixed at 0V.
Furthermore, if the Vctrl1 and Vctrl2 pins are connected together it is possible to achieve the full analog attenuation range with only a small degradation in input IP 3 performance. Applications include AG C circuits and temperature compensation of multiple gain stages in microwave point to point and VSAT radios.
