The AD8318 is a demodulating logarithmic amplifier, capable of accurately converting an RF input signal to a corresponding decibel-scaled output voltage. It employs the progressive compression technique over a cascaded amplifier chain, each stage of which is equipped with a detector cell. The device is used in measurement or controller mode. The AD8318 maintains accurate log conformance for signals of 1 MHz to 6 GHz and provides useful operation to 8 GHz. The input range is typically 60 dB (re: 50 Ω) with error less than ±1 dB. The AD8318 has a 10 ns response time that enables RF burst detection to beyond 45 MHz. The device provides unprecedented logarithmic intercept stability vs. ambient temperature conditions. A 2 mV/°C slope temperature sensor output is also provided for additional system monitoring. A single supply of 5 V is required. Current consumption is typically 68 mA. Power consumption decreases to <1.5 mW when the device is disabled.

The AD8318 can be configured to provide a control voltage to a VGA, such as a power amplifier or a measurement output, from Pin VOUT. Because the output can be used for controller applications, wideband noise is minimal. In this mode, the setpoint control voltage is applied to VSET. The feedback loop through an RF amplifier is closed via VOUT, the output of which regulates the amplifier output to a magnitude corresponding to VSET. The AD8318 provides 0 V to 4.9 V output capability at the VOUT pin, suitable for controller applications. As a measurement device, Pin VOUT is externally connected to VSET to produce an output voltage, V_OUT, which is a decreasing linear-in-dB function of the RF input signal amplitude.

The logarithmic slope is nominally −25 mV/dB but can be adjusted by scaling the feedback voltage from VOUT to the VSET interface. The intercept is 20 dBm (re: 50 Ω, CW input) using the INHI input. These parameters are very stable against supply and temperature variations.

The AD8318 is fabricated on a SiGe bipolar IC process and is available in a 4 mm × 4 mm, 16-lead LFCSP for the operating temperature range of –40°C to +85°C.

Applications

RF transmitter PA setpoint control and level monitoring

RSSI measurement in base stations, WLAN, WiMAX, and radars

Data Sheet, Rev. B, 4/07

Part#	RF Frequency (MHz)	Dynamic Range (dB)	Temp Stability (dB)	Response Time (ns typ)	Voltage Supply (V)	Supply Current (max)	Package	Price* (1000-4999)
AD606	-	80	-	400	4.5 to 5.5	13	16-Lead DIP, 16-Lead SOIC	$21.74
AD640	-	50	±1	10	+/- 4.5 to +/- 7.5	44	20-Lead DIP, 20-Lead LCC, 20-Lead PLCC	$36.05
AD641	-	44	±1	10	+/- 4.5 to +/- 7.5	44	20-Lead DIP, 20-Lead LCC, 20-Lead PLCC	$32.43
AD8302	2,700	60	±1	60	2.7 to 5.5	19	14-Lead TSSOP	$12.00
AD8306	5 to 400	100	±1	73	2.7 to 5.5	16	16-Lead SOP	$14.50
AD8307	dc to 500	92	±1	400	2.7 to 5.5	8	8-Lead SOIC/DIP	$6.00
AD8309	5 to 500	100	±1	67	2.7 to 5.5	16	16-Lead TSSOP	$7.75
AD8310	dc to 440	100	±1	15	2.7 to 5.5	8	8-Lead SOIC	$3.95
AD8311	100 to 2500	50	±0.5	150	2.7 to 5.5	8.5	WLCSP	$1.25
AD8312	50 to 3500	45	±0.5	70	2.7 to 5.5	4.2	WLCSP	$1.25
AD8313	100 to 2500	70	±1.25	40	2.7 to 5.5	14	8-Lead uSOIC	$7.90
AD8314	100 to 2700	45	±1	70	2.7 to 5.5	4.5	8-Lead uSOIC/CSP	$1.09
AD8315	100 to 2500	50	±1	150	2.7 to 5.5	8.5	8-Lead uSOIC	$3.95
AD8316	100 to 2500	49	±1	50	2.7 to 5.5	8.5	16-Lead CSP	-
AD8317	1 to 10000	55	±0.5	6	3 to 5.5	20	8-Lead CSP	$3.93
AD8318	1 to 8000	70	±0.5	10	4.5 to 5.5	68	16-Lead CSP	$4.99
AD8319	1 to 10000	45	±0.5	6	3 to 5.5	22	8-Lead CSP	$1.75
ADL5519	1 kHz to 10000	62	±0.5	6	3 to 5.5	56	32-Lead LFCSP	$4.98

* The pricing listed here is provided only for budgetary purposes as recommended list price in U.S. Dollars in the United States ex factor per unit for the stated volume. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.
** Pricing is currently unavailable. Click on the product number to see the Product Page for additional information.

The model number is a specific version of a generic that can be purchased or sampled.

Status indicates the current lifecycle of the product. This can be one of 4 stages:

• Pre-Release: The model has not been released to general production, but samples may be available.
• Production: The model is currently being produced, and generally available for purchase and sampling.
• Last Time Buy: The model has been scheduled for obsolescence, but may still be purchased for a limited time.
• Obsolete: The specific part is obsolete and no longer available. Other models listed in the table may still be available (if they have a status that is not obsolete).

The package for this IC (i.e. DIP, SOIC, BGA). An Evaluation Board is a board engineered to show the performance of the model, the part is included on the board.

For detailed drawings and chemical composition please consult our  Package Site

Pin Count is the number of pins, balls, or pads on the device. Pin-out diagrams & pin function descriptions may be found in the datasheet.

This is the acceptable operating range of the device. The various ranges specified are as follows:

• Commercial: 0 to +70 degrees Celsius
• Military : -55 to +125 degrees Celsius
• Industrial: Temperature ranges may vary by model. Please consult the datasheet for more information.
• Automotive: -40 to +125 degrees Celsius

The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.

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