آر اف (فرکانس رادیویی) و بی‌سیم آشکارساز آر اف

Product Attributes

Introduction

The AD8314 is a complete low cost subsystem for the measurement and control of RF signals in the frequency range of 100 MHz to 2.7 GHz, with a typical dynamic range of 45 dB, intended for use in a wide variety of cellular handsets and other wireless devices. It provides a wider dynamic range and better accuracy than possible using discrete diode detectors. In particular, its temperature stability is excellent over the full operating range of -40°C to +85°C. Its high sensitivity allows control at low power levels, thus reducing the amount of power that needs to be coupled to the detector. It is essentially a voltage-responding device, with a typical signal range of 1.25 mV to 224 mV rms or -58 dBV to -13 dBV. This is equivalent to -45 dBm to 0 dBm, re 50 Ω. For convenience, the signal is internally ac-coupled, using a 5 pF capacitor to a load of 3 kΩ in shunt with 2 pF. This highpass coupling, with a corner at approximately 16 MHz, determines the lowest operating frequency. Therefore, the source can be dc grounded. The AD8314 provides two voltage outputs. The first, V_UP, increases from close to ground to about 1.2 V as the input signal level increases from 1.25 mV to 224 mV. This output is intended for use in measurement mode. Consult the Applications section for information on this mode. A capacitor can be connected between the V_UP and FLTR pins when it is desirable to increase the time interval over which averaging of the input waveform occurs. The second output, V_DN, is an inversion of V_UP but with twice the slope and offset by a fixed amount. This output starts at about 2.25 V (provided the supply voltage is 2.3 V) for the minimum input and falls to a value close to ground at the maximum input. This output is intended for analog control loop applications. A setpoint voltage is applied to VSET, and V_DN is then used to control a VGA or power amplifier. Here again, an external filter capacitor can be added to extend the averaging time. Consult the Applications section for information on this mode. The AD8314 is available in 8-lead MSOP and 8-lead LFCSP packages and consumes 4.5 mA from a 2.7 V to 5.5 V supply. When powered down, the typical sleep current is 20 μA.

Features

• Complete RF detector/controller function
• Typical range: −58 dBV to −13 dBV, −45 dBm to 0 dBm, re 50 Ω
• Frequency response from 100 MHz to 2.7 GHz
• Temperature-stable linear-in-dB response Accurate to 2.7 GHz
• Rapid response: 70 ns to a 10 dB step
• Low power: 12 mW at 2.7 V
• Power down to 20 μA

Applications

• Cellular handsets (TDMA, CDMA, GSM)
• RSSI and TSSI for wireless terminal devices
• Transmitter power measurement and control