The AD641 is a 250 MHz, demodulating logarithmic amplifier with an accuracy of ±2.0 dB and 44 dB dynamic range. The AD641 uses a successive detection architecture to provide an output current that is logarithmically proportional to its input voltage. The output current can be converted to a voltage using one of several on-chip resistors to select the slope. A single AD641 provides up to 44 dB of dynamic range at speeds up to 250 MHz, and two cascaded AD641s together can provide 58 dB of dynamic range at speeds up to 250 MHz. The AD641 is fully stable and well characterized over either the industrial or military temperature ranges.

The AD641 is not a logarithmic building block, but rather a complete logarithmic solution for compressing and measuring dynamic range signals. The AD641 is comprised of five stages and each stage has a full wave rectifier, whose current pends on the absolute value of its input voltage. The output of these stages are summed together to provide the demodulated output current scaled at 1 mA per decade (50 µA/dB).

Without utilizing the 10x input attenuator, log conformance of 2.0 dB is maintained over the input range -44 dBm to 0 dBm. The attenuator offers the most flexibility without significantly impacting performance.

The 250 MHz bandwidth and temperature stability make this product ideal for high speed signal power measurement in RF/IF systems. ECM/Radar and Communication applications are routinely in the 100 MHz-180 MHz range for power measurement. The bandwidth and accuracy, as well as dynamic range, make this part ideal for high speed, wide dynamic range signals.

The AD641 is offered in industrial (-40°C to +85°C) and military (-55°C to +125°C) package temperature ranges. Industrial versions are available in plastic DIP and PLCC; MIL versions are packaged in cerdip.

An evaluation board is available for this product and may be ordered using the following product number: AD641-EB.

Part#	Product Description	RF Frequency (MHz)	Dynamic Range (dB)	Temp Stability (dB)	Response Time (ns typ)	Voltage Supply (V)	Supply Current (max)	Package	Price* (1000-4999)
AD606	Limiter Output	-	80	-	400	4.5 to 5.5	13	16-Lead DIP, 16-Lead SOIC	$22.00
AD640	Military Specified Part Available	-	50	±1	10	+/- 4.5 to +/- 7.5	44	20-Lead DIP, 20-Lead LCC, 20-Lead PLCC	$36.48
AD641	Military Specified Part Available	-	44	±1	10	+/- 4.5 to +/- 7.5	44	20-Lead DIP, 20-Lead LCC, 20-Lead PLCC	$32.82
AD8302	Dual-Channel Gain and Phase Outputs	2,700	60	±1	60	2.7 to 5.5	19	14-Lead TSSOP	$12.14
AD8306	Military Specified Part Available	5 to 400	100	±1	73	2.7 to 5.5	16	16-Lead SOP	$14.67
AD8307	High Dynamic Range	dc to 500	92	±1	400	2.7 to 5.5	8	8-Lead SOIC/DIP	$6.07
AD8309	Limiter Output	5 to 500	100	±1	67	2.7 to 5.5	16	16-Lead TSSOP	$7.84
AD8310	High Dynamic Range	dc to 440	100	±1	15	2.7 to 5.5	8	8-Lead SOIC	$4.00
AD8311	Low Power for Battery Operation	100 to 2500	50	±0.5	150	2.7 to 5.5	8.5	WLCSP	$1.27
AD8312	Low Power for Battery Operation	50 to 3500	45	±0.5	70	2.7 to 5.5	4.2	WLCSP	$1.27
AD8313	Industry Standard	100 to 2500	70	±1.25	40	2.7 to 5.5	14	8-Lead uSOIC	$7.99
AD8314	Industry Standard	100 to 2700	45	±1	70	2.7 to 5.5	4.5	8-Lead uSOIC/CSP	$1.10
AD8315	Low Power for Battery Operation	100 to 2500	50	±1	150	2.7 to 5.5	8.5	8-Lead uSOIC	$4.00
AD8316	Dual Output AD8315	100 to 2500	49	±1	50	2.7 to 5.5	8.5	16-Lead CSP	-
AD8317	Available in Die	1 to 10000	55	±0.5	6	3 to 5.5	20	8-Lead CSP	$3.98
AD8318	Integrated Temp Sensor	1 to 8000	70	±0.5	10	4.5 to 5.5	68	16-Lead CSP	$5.05
AD8319	Pin-compatible with AD8317	1 to 10000	45	±0.5	6	3 to 5.5	22	8-Lead CSP	$1.77
ADL5513	125°C Operation, Broadband	1 to 4000	80	±0.5	10	2.7 to 5.5	-	16-Lead CSP	-
ADL5519	Dual-Channel AD8317	1 kHz to 10000	62	±0.5	6	3 to 5.5	56	32-Lead LFCSP	$5.04

* 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.

This is the date Analog Devices, Inc. anticipates that the product will ship from the warehouse. Most orders ship within 48 hours of this date.Once an order has been placed, Analog Devices, Inc. will send an Order Acknowledgement email to confirm your delivery date. It is important to note the scheduled dock date on the order entry screen. We do take orders for items that are not in stock, so delivery may be scheduled at a future date. Also, please note the warehouse location for the product ordered. We have warehouses in the United States, Europe and Southeast Asia. Transit times from these sites may vary.

Due to environmental concerns, ADI offers many of our products in lead-free versions. For more information about lead-free parts, please consult our Pb (Lead) free information page.