AD8367ARU

AD8367ARU Analogg Devices The AD8367 is a high performance 45 dB variable gain amplifier with linear-in-dB gain control for use from low frequencies up to several hundred megahertz. The range, flatness, and accuracy of the gain response are achieved using Analog Devices' X-AMP® architecture, the most recent in a series of powerful proprietary concepts for variable gain applications, which far surpasses what can be achieved using competing techniques. The input is applied to a 9-stage, 200 I© resistive ladder network. Each stage has 5 dB of loss, giving a total attenuation of 45 dB. At maximum gain, the first tap is selected; at progressively lower gains, the tap moves smoothly and continuously toward higher attenuation values. The attenuator is followed by a 42.5 dB fixed gain feedback amplifier-essentially an operational amplifier with a gain bandwidth product of 100 GHz-and is very linear, even at high frequencies. The output third order intercept is +20 dBV at 100 MHz (+27 dBm, re 200 I©), measured at an output level of 1 V p-p with VS = 5 V. The analog gain-control input is scaled at 20 mV/dB and runs from 50 mV to 950 mV. This corresponds to a gain of aˆ'2.5 dB to +42.5 dB, respectively, when the gain up mode is selected and +42.5 dB to aˆ'2.5 dB, respectively, when gain down mode is selected. The gain down, or inverse, mode must be selected when operating in AGC in which an integrated square-law detector with an internal setpoint is used to level the output to 354 mV rms, regardless of the crest factor of the output signal. A single external capacitor sets up the loop averaging time. The AD8367 can be powered on or off by a voltage applied to the ENBL pin. When this voltage is at a logic LO, the total power dissipation drops to the milliwatt range. For a logic HI, the chip powers up rapidly to its normal quiescent current of 26 mA at 25°C. The AD8367 is available in a 14-lead TSSOP package for the industrial temperature range of aˆ'40°C to +85°C.