The AD605 is a low noise, accurate, dual-channel, linear-in-dB variable gain amplifier (VGA), optimized for any application requiring high performance, wide bandwidth variable gain control. Operating from a single 5 V supply, the AD605 provides differential inputs and unipolar gain control for ease of use. Added flexibility is achieved with a user-determined gain range and an external reference input that provide user-determined gain scaling (dB/V).

The high performance linear-in-dB response of the AD605 is achieved with the differential input, single-supply, exponential amplifier (DSX-AMP) architecture. Each of the DSX-AMPs comprises a variable attenuator of 0 dB to −48.4 dB followed by a high speed, fixed-gain amplifier. The attenuator is based on a 7-stage R-1.5R ladder network. The attenuation between tap points is 6.908 dB, and 48.360 dB for the entire ladder network. The DSX-AMP architecture results in 1.8 nV/√Hz input noise spectral density and accepts a ±2.0 V input signal when VOCM is biased at VP/2.

Each independent channel of the AD605 provides a gain range of 48 dB that can be optimized for the application. Gain ranges between −14 dB to +34 dB and 0 dB to +48 dB can be selected by a single resistor between Pin FBK and Pin OUT. The lower and upper gain ranges are determined by shorting Pin FBK to Pin OUT or leaving Pin FBK unconnected, respectively. The two channels of the AD605 can be cascaded to provide 96 dB of very accurate gain range in a monolithic package.

The gain control interface provides an input resistance of approximately 2 MΩ and scale factors from 20 dB/V to 30 dB/V for a VREF input voltage of 2.5 V to 1.67 V, respectively. Note that scale factors up to 40 dB/V are achievable with reduced accuracy for scales above 30 dB/V. The gain scales linearly in dB with control voltages (VGN) of 0.4 V to 2.4 V for the 20 dB/V scale and 0.20 V to 1.20 V for the 40 dB/V scale. When VGN is <50 mV, the amplifier is powered down to draw 1.9 mA. Under normal operation, the quiescent supply current of each amplifier channel is only 18 mA.

The AD605 is available in a 16-lead PDIP and a 16-lead SOIC_N package and is guaranteed for operation over the −40°C to +85°C temperature range.

Applications

Ultrasound and sonar time-gain controls

High performance AGC systems

Signal measurement

Data Sheet, Rev. E, 5/07

Part#	Gain Control	-3 dB BW (MHz)	Gain Low End (dB)	Gain High End (dB)	Number of Channels	Spectral Noise (nV/rtHz)	Supply Voltage (V)	Supply Current (max)	Gain Accuracy (dB)	1 dB Comp Point (dBm)	Package	Price* (1000-4999)
AD600	Analog	35	0	+40	2	1.4	±5	14mA	-	-	-	$16.41
AD602	Analog	35	-10	+30	2	1.4	±5	14mA	-	-	-	$13.20
AD603	Analog	90	-11	+31	1	1.4	±5	20mA	±0.5	-	8-Lead DIP, 8-Lead SOIC	$4.35
AD604	Analog	40	0	+48	2	0.8	±5	31mA	±0.3	15	24-Lead SOIC, 24-Lead SSOP	$16.25
AD605	Analog	40	-14	+34	2	1.8	+5	23mA	±0.2	15	16-Lead SOIC	$9.79
AD8260	Digital	180	-6	+24	1	2.4	+3.3	28mA	+0.25	-	-	$3.79
AD8320	Digital	150	-10	+26	1	53	+12	105mA	±0.2	22.5	20-Lead SOIC	-
AD8321	Digital	120	-27.4	+26	1	20	+9	90mA	±1	19.5	20-Lead SOIC	$4.35
AD8322	Digital	180	-12.6	+29.5	1	64	+5	113mA	±2	19	28-Lead TSSOP	$3.15
AD8323	Digital	100	-26	+27.5	1	-	+5	-	-	-	28-Lead TSSOP	$3.30
AD8324	Digital	100	-25.5	+33.5	1	157	+3.3	207mA	±1	21	20-Lead LFCSP, 20-Lead QSOP	$1.71
AD8325	Digital	100	-29.5	+30	1	56	+5	133mA	±1	18.5	28-Lead TSSOP	$3.30
AD8326	Digital	100	-26	+27.5	1	100	±5	157mA	±1	26.5	28-Lead PSOP, 28-Lead TSSOP	$3.90
AD8327	Digital	160	-18	+30	1	64	+5	105mA	±1	18	20-Lead TSSOP	$3.75
AD8328	Digital	107	-27.5	+31.5	1	135	-	120mA	±1	18.4	20-Lead LFCSP, 20-Lead QSOP	$1.90
AD8330	Analog	150	0	+50	1	5	+6	20mA	±0.5	-	16-Lead LFCSP, 16-Lead QSOP	$4.39
AD8331	Analog	120	-4.5	+43	1	0.74	+5	25mA	+0.5	7	-	$5.39
AD8332	Analog	120	-4.5	+43.5	2	0.74	+5	58mA	+0.5	7	28-Lead TSSOP, 32-Lead CSP	$10.44
AD8334	Analog	100	+4.5	+43.5	4	0.74	+5	116mA	+0.5	7	64-Lead LFCSP	$14.49
AD8335	Analog	70	-10	+38	4	1.3	+5	76mA	±0.2	18	64-Lead LFCSP	$12.00
AD8336	Analog	115	-14	+46	1	3	±12	25mA	±0.5	11	16-Lead LFCSP	$4.59
AD8337	Analog	280	0	+24	1	2.2	±5	15mA	±0.25	-	8-Lead LFCSP	$2.49
AD8367	Analog	500	-2.5	+42.5	1	1.84	+5.5	26mA	±0.2	8.1	14-Lead TSSOP	$4.55
AD8368	Analog	800	-12	+22	1	-	+5	-	±0.4	13	24-Lead LFCSP	$4.55
AD8369	Digital	600	-5	+40	1	2	+5.5	37mA	±0.5	0.5	16-Lead TSSOP	$4.20
AD8370	Digital	700	+25	+34	1	2.1	+5.5	78mA	-	14	16-Lead TSSOP	$4.20
AD8375	Digital	690	-4	+20	1	-	+5	130mA	±0.2	19	24-Lead LFCSP	$4.49
AD8376	Digital	690	-4	+20	2	-	+5	260mA	±0.2	19	32-Lead CSP	$6.49
ADL5330	Analog	3000	-34	+22	1	-	+5	240mA	-	1.2	24-Lead LFCSP	$4.98
ADL5390	Analog	2400	-	+7	1	-	+5	130mA	-	9.6	24-Lead LFCSP	$7.50
ADL5391	Analog	2000	-	+9.5	1	26.7	+5	135mA	-	15.1	16-Lead LFCSP	$4.89

* 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.
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