Low-power, Variable Gain Amplifier - National Semiconductor

The CLC5523 is a low power, wideband, DC-coupled, voltage- controlled gain Amplifier It provides a voltage-controlled gain block coupled with a current feedback output Amplifier High impedance inputs and minimum dependence of bandwidth on gain make the CLC5523 easy to use in a wide range of applications. This Amplifier is suitable as a continuous gain control element in a variety of electronic systems which benefit from a wide bandwidth of 250MHz and high slew rate of 1800V/ms, with only 135mW of power dissipation. Input impedances in the megaohm range on both the signal and gain control inputs simplify driving the CLC5523 in any application. The CLC5523 CAN be configured to use pin 3 as a low impedance input making it an ideal Interface for current inputs. By using the CLC5523s inverting configuration in which RG is driven directly, inputs which exceed the devices input voltage range may be used. The gain control input (VG), with a 0 to 2V input range, and a linear-in-dB gain control, simplifies the implementation of AGC circuits. The gain control circuit CAN adjust the gain as fast as 4dB/ns. Maximum gains from 2 to 100 are accurately and simply set by two external resistors while attenuation of up to 80dB from this gain CAN be achieved. The extremely high slew rate of 1800V/ms and wide bandwidth provides high speed rise and fall times of 2.0ns, with settling time for a 2 volt step of only 22ns to 0.2%. In time domain applications where linear phase is important with gain adjust, the internal cur- rent mode circuitry maintains low deviation of delay over a wide gain adjust range. By National Semiconductor Corporation