Low Cost, DC to 500 MHz, 92 dB Logarithmic Amplifier

The AD8307 is the first logarithmic amplifier made available in an 8-lead SOICN package. It is a complete 500 MHz monolithic demodulating logarithmic amplifier based on the progressive compression (successive detection) technique, providing a dynamic range of 92 dB to ±3 dB law conformance and 88 dB to a tight ±1 dB error bound at all frequencies up to 100 MHz. The AD8307 is extremely stable and easy to use, requiring no significant external components. A single-supply voltage of 2.7 V to 5.5 V at 7.5 mA is needed. A fast acting CMOS-compatible control pin can disable the AD8307 to a standby current of 150 μA.

The AD8307 operates over the industrial temperature range of −40°C to +85°C and is available in an 8-lead SOIC package and an 8-lead PDIP.

Applications

* Conversion of signal level to decibel form

* Transmitter antenna power measurement

* Receiver signal strength indication (RSSI)

* Low cost radar and sonar signal processing

* Network and spectrum analyzers (to 120 dB)

* Signal level determination down to 20 Hz

* True decibel ac mode for multimeters

* Complete multistage logarithmic amplifier

* 92 dB dynamic range: –75 dBm to +17 dBm to –90 dBm using matching network

* Single supply of 2.7 V minimum at 7.5 mA typical

* DC to 500 MHz operation, ±1 dB linearity