1 MHz to 10 GHz , 50 dB Log Detector/Controller
The AD8317 can be configured to provide a control voltage to a power amplifier or a measurement output from the VOUT pin. Because the output can be used for controller applications, special attention has been paid to minimize wideband noise. In this mode, the setpoint control voltage is applied to the VSET pin.
The feedback loop through an RF amplifier is closed via VOUT, the output of which regulates the output of the amplifier to a magnitude corresponding to VSET. The AD8317 provides 0 V to (VPOS − 0.1 V) output capability at the VOUT pin, suitable for controller applications. As a measurement device, VOUT is externally connected to VSET to produce an output voltage VOUT that is a decreasing linear-in-dB function of the RF input signal amplitude.
The logarithmic slope is −22 mV/dB, determined by the VSET interface. The intercept is 15 dBm (re: 50 Ω, CW input) using the INHI input. These parameters are very stable against supply and temperature variations.
The AD8317 is fabricated on a SiGe bipolar IC process and is available in a 2 mm × 3 mm, 8-lead LFCSP with an operating temperature range of −40°C to +85°C.
Data Sheet, Rev. A, 8/07