Overview
Features and Benefits
- Complete RF detector/controller function
- >50 dB range at 0.9 GHz (-49 dBm to +2 dBm, re 50 Ω)
- Accurate scaling from 0.1 GHz to 2.5 GHz
- Temperature-stable linear-in-dB response
- Log slope of 23 mV/dB, intercept at -60 dBm at 0.9 GHz
- True integration function in control loop
- Low power: 20 mW at 2.7 V, 38 mW at 5 V
- Power-down to 10.8 µW
Product Details
The AD8315 is a complete low cost subsystem for the precise control of RF power amplifiers operating in the frequency range 0.1 GHz to 2.5 GHz and over a typical dynamic range of 50 dB. It is intended for use in cellular handsets and other batteryoperated wireless devices. The log amp technique provides a much wider measurement range and better accuracy than controllers using diode detectors. In particular, the temperature stability is excellent over a specified range of −30°C to +85°C.
Its high sensitivity allows control at low signal levels, thus reducing the amount of power that must be coupled to the detector.
For convenience, the signal is internally ac-coupled. This high-pass coupling, with a corner at approximately 0.016 GHz, determines the lowest operating frequency. Therefore, the source can be dc grounded.
The AD8315 provides a voltage output, VAPC, that has the voltage range and current drive to directly connect to most handset power amplifiers’ gain control pin. VAPC can swing from 250 mV above ground to within 200 mV below the supply voltage. Load currents of up to 6 mA can be supported.
The setpoint control input is applied to the VSET pin and has an operating range of 0.25 V to 1.4 V. The associated circuit determines the slope and intercept of the linear-in-dB measurement system; these are nominally 23 mV/dB and −60 dBm for a 50 Ω termination (−73 dBV) at 0.9 GHz. Further simplifying the application of the AD8315, the input resistance of the setpoint interface is over 100 MΩ, and the bias current is typically 0.5 μA.
The AD8315 is available in MSOP and LFCSP packages and consumes 8.5 mA from a 2.7 V to 5.5 V supply. When powered down, the sleep current is 4 μA.
Applications
- Single, dual, and triple band mobile handset (GSM, DCS, EDGE)
- Transmitter power control
Product Categories
Markets and Technologies
Product Lifecycle
Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
Documentation & Resources
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FAQs7/26/2017
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Noise Figure and Logarithmic Amplifiers [The Wit and Wisdom of Dr. Leif—6]6/1/2008 Analog Dialogue
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Measuring the RF Power in CDMA2000 and W-CDMA High Power Amplifiers (HPAs)11/1/2005
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Detecting Fast RF Bursts using Log Amps12/1/2002
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Make Precise Base-Station Power Measurements11/2/2002
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Measurement and Control of RF Power (Part III)2/9/2001
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Measurement and Control of RF Power (Part II)12/1/2000
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Measurement and Control of RF Power (Part I)10/19/2000
Tools & Simulations
Design Tools
ADIsimRF
ADIsimRF is an easy-to-use RF signal chain calculator. Cascaded gain, noise, distortion and power consumption can be calculated, plotted and exported for signal chains with up to 50 stages. ADIsimRF also includes an extensive data base of device models for ADI’s RF and mixed signal components.
ADIsimPLL™
ADIsimPLL enables the rapid and reliable evaluation of new high performance PLL products from ADI. It is the most comprehensive PLL Synthesizer design and simulation tool available today. Simulations performed include all key non-linear effects that are significant in affecting PLL performance. ADIsimPLL removes at least one iteration from the design process, thereby speeding the design- to-market.
Design Resources
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.View our quality and reliability program and certifications for more information.
| Part Number | Material Declaration | Reliability Data | Pin/Package Drawing | CAD Symbols, Footprints & 3D Models |
|---|---|---|---|---|
| AD8315ACPZ-REEL7 | Material Declaration | Reliability Data | 8-Lead LFCSP (3mm x 2mm x 0.75mm w/ EP) | |
| AD8315ARMZ | Material Declaration | Reliability Data | 8-Lead MSOP | |
| AD8315ARMZ-RL | Material Declaration | Reliability Data | 8-Lead MSOP | |
| Wafer Fabrication Data |
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Sample & Buy
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Lead Times
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Sampling
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Evaluation Boards
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.