AD8313ARM

The AD8313ARM is one member of the AD8313 series.The AD8313 is a complete multistage demodulating logarithmic amplifier, capable of accurately converting an RF signal at its differential input to an equivalent decibel-scaled value at its dc output.

Features of the AD8313ARM are:(1)wide bandwidth: 0.1 GHz to 2.5 GHz min;(2)high dynamic range: 70 dB to  3.0 dB;(3)fast response: 40 ns full-scale typical;(4)scaling stable over supply and temperature;(5)controller mode with error output.The AD8313 uses a cascade of eight amplifier/limiter cells,each having a nominal gain of 8 dB and a 3 dB bandwidth of 3.5 GHz, for a total midband gain of 64 dB. At each amplifier output, a detector (rectifier) cell is used to convert the RF signal to baseband form; a ninth detector cell is placed directly at the input of the AD8313. The current-mode outputs of these cells are summed to generate a piecewise linear approximation to the logarithmic function, and converted to a low impedance voltage-mode output by a transresistance stage, which also acts as a low-pass filter.When used as a log amp, the scaling is determined by a separate feedback interface (a transconductance stage) that sets the slope to approximately 18 mV/dB; used as a controller, this stage accepts the setpoint input.

The absolute maximum ratings of the AD8313ARM can be summarized as:(1)Supply Voltage VS:5.5 V;(2)internal power dissipation:200 mW;(3)maximum junction temperature:+125°C;(4)operating temperature range:40°C to +85°C.Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device.  This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied.Exposure to absolute maximum rating conditions for extended periods may affect device reliability.The signal may be coupled to the AD8313 in a variety of ways.In all cases, there must not be a dc path from the input pins to ground. Some of the possibilities include: dual input coupling capacitors, a flux-linked transformer, a printed-circuit balun, direct drive from a directional coupler, or a narrow-band impedance matching network.