Analog Devices AD605BR-REEL7, AD605BR-REEL, AD605BR, AD605BN, AD605AR-REEL7 Datasheet

a		Dual, Low Noise, Single-Supply
		Variable Gain Amplifier
		AD605

FEATURES

Two Independent Linear-in-dB Channels

Input Noise at Maximum Gain: 1.8 nV/√Hz, 2.7 pA/√Hz Bandwidth: 40 MHz (–3 dB)

Differential Input

Absolute Gain Range Programmable:

–14 dB to +34 dB (FBK Shorted to OUT), through 0 dB to +48 dB (FBK Open)

Variable Gain Scaling: 20 dB/V through 40 dB/V Stable Gain with Temperature and Supply Variations Single-Ended Unipolar Gain Control

Output Common-Mode Independently Set Power Shutdown at Lower End of Gain Control Single 5 V Supply

Low Power: 90 mW/Channel

Drives A/D Converters Directly

APPLICATIONS

Ultrasound and Sonar Time-Gain Control

High Performance AGC Systems

Signal Measurement

PRODUCT DESCRIPTION

The AD605 is a low noise, accurate, dual channel, linear-in-dB variable gain amplifier, which is 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 which provides 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 comprise 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-1.5-R 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 will accept 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 which can be optimized for the application. Gain

REV. B

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

FUNCTIONAL BLOCK DIAGRAM

			PRECISION PASSIVE	FIXED GAIN
	VGN			AMPLIFIER
		GAIN	INPUT ATTENUATOR
				+34.4dB
		CONTROL		OUT
		AND
	VREF	SCALING
				FBK
				VOCM
	+IN		DIFFERENTIAL
			ATTENUATOR	AD605
	–IN		0 TO –48.4dB

ranges between –14 dB to +34 dB and 0 dB to +48 dB can be selected by a single resistor between pins FBK and OUT. The lower and upper gain range are determined by shorting pin FBK to 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 are achievable with reduced accuracy for scales above 30 dB. The gain scales linearly 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 plastic DIP and SOIC, and is guaranteed for operation over the –40°C to +85°C temperature range.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: [phone]	www.analog.com
Fax: [phone]	© Analog Devices, Inc., 2001

		(Each Channel at TA = 25 C, VS = 5 V, RS = 50 , RL = 500 , CL = 5 pF, VREF = 2.5 V
AD605–SPECIFICATIONS (Scaling = 20 dB/V), –14 dB to +34 dB gain range, unless otherwise noted.)
	Model			AD605A			AD605B
	Parameter	Conditions	Min	Typ	Max	Min	Typ	Max	Unit
	INPUT CHARACTERISTICS			175 ± 40			175 ± 40		Ω
	Input Resistance
	Input Capacitance			3.0			3.0		pF
	Peak Input Voltage			2.5 ± 2.5			2.5 ± 2.5		V
	Input Voltage Noise	VGN = 2.9 V		1.8			1.8		nV/√Hz
	Input Current Noise	VGN = 2.9 V		2.7			2.7		pA/√Hz
	Noise Figure	RS = 50 Ω, f = 10 MHz at Minimum Gain,		8.4			8.4		dB
		VGN = 2.9 V
		RS = 200 Ω, f = 10 MHz at Minimum Gain,		12			12		dB
		VGN = 2.9 V
	Common-Mode Rejection Ratio	f = 1 MHz, VGN = 2.65 V		–20			–20		dB
	OUTPUT CHARACTERISTICS
	–3 dB Bandwidth	Constant with Gain		40			40		MHz
	Slew Rate	VGN = 1.5 V, Output = 1 V Step		170			170		V/µs
	Output Signal Range	RL ≥ 500 Ω		2.5 ± 1.5			2.5 ± 1.5		V
	Output Impedance	f = 10 MHz		2			2		Ω
	Output Short-Circuit Current			±40			±40		mA
	Harmonic Distortion	VGN = 1 V, VOUT = 1 V p-p,
	HD2	f = 1 MHz		–64			–64		dBc
	HD3	f = 1 MHz		–68			–68		dBc
	HD2	f = 10 MHz		–51			–51		dBc
	HD3	f = 10 MHz		–53			–53		dBc
	Two-Tone Intermodulation	RS = 0 Ω, VGN = 2.9 V, VOUT = 1 V p-p
	Distortion (IMD)	f = 1 MHz		–72			–72		dBc
		f = 10 MHz		–60			–60		dBc
	1 dB Compression Point	f = 10 MHz, VGN = 2.9 V, Output Referred		+15			+15		dBm
	Third Order Intercept	f = 10 MHz, VGN = 2.9 V, VOUT = 1 V p-p,		–1			–1		dBm
		Input Referred
	Channel-to-Channel Crosstalk	Ch1: VGN = 2.65 V, Inputs Shorted,		–70			–70		dB
		Ch2: VGN = 1.5 V (Mid Gain), f = 1 MHz,
		VOUT = 1 V p-p		±2.0			±2.0
	Group Delay Variation	1 MHz < f < 10 MHz, Full Gain Range							ns
	VOCM Input Resistance			45			45		kΩ
	ACCURACY
	Absolute Gain Error
	–14 dB to –11 dB	0.25 V < VGN < 0.40 V	–1.2	+1.0	+3.0	–1.2	+0.75	+3.0	dB
	–11 dB to +29 dB	0.40 V < VGN < 2.40 V	–1.0	±0.3	+1.0	–1.0	±0.2	+1.0	dB
	+29 dB to +34 dB	2.40 V < VGN < 2.65 V	–3.5	–1.25	+1.2	–3.5	–1.25	+1.2	dB
	Gain Scaling Error	0.4 V < VGN < 2.4 V		±0.25			±0.25		dB/V
	Output Offset Voltage	VREF = 2.500 V, VOCM = 2.500 V	–50	±30	50	–50	±30	50	mV
	Output Offset Variation	VREF = 2.500 V, VOCM = 2.500 V		30	95		30	50	mV
	GAIN CONTROL INTERFACE
	Gain Scaling Factor	VREF = 2.5 V, 0.4 V < VGN < 2.4 V	19	20	21	19	20	21	dB/V
		VREF = 1.67 V		30			30		dB/V
	Gain Range	FBK Short to OUT		–14 – +34			–14 – +34		dB
		FBK Open		0 – +48			0 – +48		dB
	Input Voltage (VGN) Range	20 dB/V, VREF = 2.5 V		0.1 – 2.9			0.1 – 2.9		V
	Input Bias Current			–0.4			–0.4		µA
	Input Resistance			2			2		MΩ
	Response Time	48 dB Gain Change		0.2			0.2		µs
	POWER SUPPLY
	Power Dissipation			90			90		mW
	VREF Input Resistance			10			10		kΩ
	Quiescent Supply Current	VPOS		18	23		18	23	mA
	Power Down	VPOS, VGN < 50 mV		1.9	3.0		1.9	3.0	mA
	Power-Up Response Time	48 dB Gain, VOUT = 2 V p-p		0.6			0.6		µs
	Power-Down Response Time			0.4			0.4		µs

–2–

REV. B

AD605

ABSOLUTE MAXIMUM RATINGS*

Supply Voltage +VS

Pins 12, 13 (with Pins 4, 5 = 0 V) . . . . . . . . . . . . . . . 6.5 V Input Voltages Pins 1–3, 6–9, 16 . . . . . . . . . . . . . . . VPOS, 0 Internal Power Dissipation

Plastic (N) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 W Small Outline (R) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 W Operating Temperature Range . . . . . . . . . . . –40°C to +85°C Storage Temperature Range . . . . . . . . . . . . –65°C to +150°C Lead Temperature, Soldering 60 seconds . . . . . . . . . . 300°C

*Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

PIN CONFIGURATION

VGN1
	1				16	VREF
–IN1
	2				15	OUT1
+IN1
	3				14	FBK1
GND1		AD605				VPOS
	4				13
GND2		TOP VIEW
	5	(Not to Scale)			12	VPOS
+IN2
	6				11	FBK2
–IN2						OUT2
	7				10
VGN2
	8				9	VOCM

					ORDERING GUIDE
	Model			Temperature Range		Package Description		Package Option	JA
	AD605AN			–40°C to +85°C		Plastic DIP		N-16	85°C/W
	AD605AR			–40°C to +85°C		Small Outline IC (SOIC)		R-16A	100°C/W
	AD605BN			–40°C to +85°C		Plastic DIP		N-16	85°C/W
	AD605BR			–40°C to +85°C		Small Outline IC (SOIC)		R-16A	100°C/W
	AD605ACHIPS					DIE
	AD605AR-REEL					13" Reel
	AD605AR-REEL7					7" Reel
	AD605BR-REEL					13" Reel
	AD605BR-REEL7					7" Reel
	AD605-EB					Evaluation Board
				PIN FUNCTION DESCRIPTIONS
				16-Lead Package for Dual Channel AD605
Pin No.	Mnemonic		Description
1	VGN1		CH1 Gain-Control Input and Power-Down Pin. If grounded, device is off, otherwise positive voltage
			increases gain.
2	–IN1		CH1 Negative Input.
3	+IN1		CH1 Positive Input.
4	GND1		Ground.
5	GND2		Ground.
6	+IN2		CH2 Positive Input.
7	–IN2		CH2 Negative Input.
8	VGN2		CH2 Gain-Control Input and Power-Down Pin. If grounded, device is off, otherwise positive voltage
			increases gain.
9	VOCM		Input to this pin defines common-mode voltage for OUT1 and OUT2.
10	OUT2		CH2 Output.
11	FBK2		Feedback Pin that Selects Gain Range of CH2.
12	VPOS		Positive Supply.
13	VPOS		Positive Supply.
14	FBK1		Feedback Pin that Selects Gain Range of CH1.
15	OUT1		CH1 Output.
16	VREF		Input to this pin sets gain-scaling for both channels: 2.5 V = 20 dB/V, 1.67 V = 30 dB/V.

CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the AD605 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high-energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.

WARNING!

ESD SENSITIVE DEVICE

REV. B

–3–

AD605–Typical Performance Characteristics (per Channel)

(VREF = 2.5 V (20 dB/V Scaling), f = 1 MHz, RL = 500 , CL = 5 pF, TA = 25 C, VSS = 5 V)
40									50
30			–40 C, +25 C, +85 C						40
									30		FBK (OPEN)
20
								GAIN – dB
									20
10														FBK (SHORT)
GAINdB–									10
0									0
–10									–10
–20									–20		0.9	1.3	1.7	2.1	2.5
		0.9	1.3	1.7	2.1	2.5			0.1	0.5						2.9
0.1	0.5						2.9

VGN – Volts

VGN – Volts

	40
	30				ACTUAL
		30dB/V					ACTUAL
	20	(VREF = 1.67V)
– dB	10				20dB/V
GAIN
					(VREF = 2.50V)
	0
	–10
	–20		0.9	1.3	1.7	2.1	2.5
	0.1	0.5						2.9

VGN – Volts

TPC 1. Gain vs. VGN	TPC 2. Gain vs. VGN for Different
	Gain Ranges

TPC 3. Gain vs. VGN for Different Gain Scalings

	40.0
	37.5	THEORETICAL
–dBV	35.0
	32.5
SCALING	ACTUAL
	27.5
	30.0
GAIN	25.0
	22.5
	20.0		1.75	2.00	2.25
	1.25	1.50				2.50
			VREF – Volts

TPC 4. Gain Scaling vs. VREF

	2.0
	1.5
– dB	1.0
					20dB/V
	0.5			VREF = 2.50V
ERROR	0.0
			30dB/V
GAIN	–0.5
			VREF = 1.67V
	–1.0
	–1.5
	–2.0
	0.2	0.7	1.2	1.7	2.2	2.7

VGN – Volts

TPC 7. Gain Error vs. VGN for Different Gain Scalings

	3.0
	2.5
	2.0
	1.5
– dB	1.0			–40 C
	0.5
ERROR
	0.0
	–0.5				+25 C
GAIN
	–1.0			+85 C
	–1.5
	–2.0
	–2.5
	–3.0
	0.2	0.7	1.2	1.7	2.2	2.7
			VGN –Volts

TPC 5. Gain Error vs. VGN at Different Temperatures

20
18		N = 50
		G(dB) =
16		G(CH1) – G(CH2)
14
PERCENTAGE
12
10
8
6

4

2

0

–0.8 –0.6 –0.4 –0.2 0.0 0.2 0.4 0.6 0.8

DELTA GAIN – dB

TPC 8. Gain Match, VGN1 = VGN2 =

1.0 V

	2.0
	1.5
– dB	1.0
			f = 1MHz
	0.5
ERROR	0.0
		f = 5MHz		f = 10MHz
GAIN	–0.5
	–1.0
	–1.5
	–2.0		1.2	1.7	2.2
	0.2	0.7				2.7
			VGN – Volts

TPC 6. Gain Error vs. VGN at Different Frequencies

	20
	18		N = 50
	16		G(dB) =
			G(CH1) – G(CH2)
	14
	PERCENTAGE
	12
	10
	8
	6
	4
	2
	0
		–0.8 –0.6 –0.4 –0.2 0.0 0.2 0.4 0.6 0.8
								DELTA GAIN – dB

TPC 9. Gain Match, VGN1 = VGN2 =

2.50 V

–4–

REV. B