Description

The AD608 provides a low power, low distortion, low noise mixer as well as a complete, monolithic logarithmic/limiting amplifier that uses a successive-detection technique. In addition, the AD608 provides both a high speed received signal strength indicator (RSSI) output with 80 dB dynamic range and a hard-limited output. The RSSI output is from a two-pole postdemodulation low-pass filter and provides a loadable output voltage of 0.2 V to 1.8 V. The AD608 operates from a single 2.7 V to 5.5 V supply at a typical power level of 21 mW at 3 V.The RF and local oscillator (LO) bandwidths both exceed 500 MHz. In a typical IF application, the AD608 can accept the output of a 240 MHz surface acoustic wave (SAW) filter and down-convert it to a nominal 10.7 MHz IF with a conversion gain of 24 dB (ZIF = 165 ?). The AD608 logarithmic/limiting amplifier section handles any IF from low frequency (LF) up to 30 MHz.The mixer is a doubly balanced gilbert-cell mixer and operates linearly for RF inputs spanning ?95 dBm to ?15 dBm. It has a nominal ?5 dBm third-order intercept. An on-board LO preamplifier requires only ?16 dBm of LO drive. The current output of the mixer drives a reverse-terminated, industry-standard 10.7 MHz, 330 ? filter.The nominal logarithmic scaling is such that the output is +0.2 V for a sinusoidal input to the IF amplifier of ?75 dBm and +1.8 V at an input of +5 dBm; over this range, the logarithmic conformance is typically ?1 dB. The logarithmic slope is proportional to the supply voltage. A feedback loop automatically nulls the input offset of the first stage down to the submicrovolt level.The AD608 limiter output provides a hard-limited signal output at 400 mV p-p. The voltage gain of the limiting amplifier to this output is more than 100 dB. Transition times are 11 ns and the phase is stable to within ?3? at 10.7 MHz for signals from ?75 dBm to +5 dBm.The AD608 is enabled by a CMOS logic-level voltage input, with a response time of 200 ns. When disabled, the standby power is reduced to 300 ?W within 400 ns.The AD608 is specified for the industrial temperature range of ?25?C to +85?C for 2.7 V to 5.5 V supplies and ?40?C to +85?C for 3.0 V to 5.5 V supplies. This device comes in a 16-lead plastic SOIC.APPLICATIONS PHS, GSM, TDMA, FM, or PM receivers Battery-powered instrumentation Base station RSSI measurements

Type:

Part number: EVAL-AD608EBZ

More details from Analog Devices Inc.