CLC5526 Datasheet | National Semiconductor

Description The CLC5526 is a high performance, digitally controlled, variable-gain amplifier (DVGA). It has been designed for use in a broad range of mixed signal and digital munication applications such as mobile radio, cellular base stations and back-channel modems where automatic-gain-control (AGC) is required to increase system dynamic range. The CLC5526 has differential input and output, allowing large signal swings on a single 5V rail. The input impedance is 200Ω. The differential output impedance is 600Ω and is designed to drive a 1 kΩ differential load. The output amplifier has excellent intermodulation performance. The CLC5526 is designed to accept signals from RF elements and maintain a terminated impedance environment. The CLC5526 maintains a 350 MHz bandwidth over its entire gain and attenuation range from +30 d B to - 12 d B. Internal clamping ensures very fast overdrive recovery. Two tone intermodulation distortion is excellent: at 150 MHz, 1 Vpp it is - 64 d Bc. Input signals to the CLC5526 are scaled by an accurate, differential R-2R resistive ladder with an input impedance of 200Ω. A scaled version of the input is selected under digital control and passed to the internal amplifier. The input mon mode level is set at 2.4V via a bandgap referenced bias generator which can be overridden by an external input. Following the resistive ladder is a fixed, 30 d B gain amplifier. The output stage mon mode voltage of the CLC5526 is set to 3V, by internal, positive supply connected resistors. Digital control of the CLC5526 is acplished by a 3-bit parallel gain control input and a data valid pin to latch the data. If the data is not latched, the DVGA is transparent to gain control updates. All digital inputs are TTL/CMOS patible. A shutdown input reduces the CLC5526 supply currrent to a few m A. During shutdown, the input termination is maintained and current attenuation settings are held. The CLC5526 operates over the industrial temperature range of - 40˚C to +85˚C....