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#	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.

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• 军用温度范围：－55ºC ～＋125ºC
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