Analog Devices AD8367 Service Manual

500 MHz, Linear-in-dB VGA

V

FEATURES

Broad-range analog variable gain: −2.5 dB to +42.5 dB 3 dB cutoff frequency of 500 MHz Gain up and gain down modes Linear-in-dB, scaled 20 mV/dB Resistive ground referenced input Nominal Z On-chip, square-law detector Single-supply operation: 2.7 V to 5.5 V

APPLICATIONS

Cellular base stations Broadband access Power amplifier control loops Complete, linear IF AGC amplifiers High speed data I/O

GENERAL DESCRIPTION

= 200 Ω

IN

ICOM

INPT

ICOM

with AGC Detector

FUNCTIONAL BLOCK DIAGRAM

PSI

4

MODE

12

5

Figure 1.

1

3

CELLS

7

AD8367

9-STAGE ATTENUATOR BY 5dB

g

m

GAUSSIAN INTERPOLATOR

PSO

11

GAIN

AD8367

ENBL

2

BIAS

SQUARE

LAW

DETECTOR

6

DETO

14

13

10

9

8

ICOM DECL HPFL VOUT

OCOM

02710-001

The AD8367 is a high performance 45 dB variable gain amplifier with linear-in-dB gain control for use from low frequencies up to several hundred megahertz. The range, flatness, and accuracy of the gain response are achieved using Analog Devices’ X-AMP® architecture, the most recent in a series of powerful proprietary concepts for variable gain applications, which far surpasses what can be achieved using competing techniques.

The input is applied to a 9-stage, 200 Ω resistive ladder network. Each stage has 5 dB of loss, giving a total attenuation of 45 dB. At maximum gain, the first tap is selected; at progressively lower gains, the tap moves smoothly and continuously toward higher attenuation values. The attenuator is followed by a

42.5 dB fixed gain feedback amplifier—essentially an operational amplifier with a gain bandwidth product of 100 GHz—and is very linear, even at high frequencies. The output third order intercept is +20 dBV at 100 MHz (+27 dBm, re 200 Ω), measured at an output level of 1 V p-p with V

= 5 V.

S

The analog gain-control input is scaled at 20 mV/dB and runs from 50 mV to 950 mV. This corresponds to a gain of −2.5 dB to +42.5 dB, respectively, when the gain up mode is selected and +42.5 dB to −2.5 dB, respectively, when gain down mode is selected. The gain down, or inverse, mode must be selected when operating in AGC in which an integrated square-law detector with an internal setpoint is used to level the output to 354 mV rms, regardless of the crest factor of the output signal. A single external capacitor sets up the loop averaging time.

The AD8367 can be powered on or off by a voltage applied to the ENBL pin. When this voltage is at a logic LO, the total power dissipation drops to the milliwatt range. For a logic HI, the chip powers up rapidly to its normal quiescent current of 26 mA at 25°C. The AD8367 is available in a 14-lead TSSOP package for the industrial temperature range of −40°C to +85°C.

Rev. A

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.

AD8367

REVISION HISTORY

Output Centering ....................................................................... 12

RMS Detection ........................................................................... 13

Applications..................................................................................... 14

Input and Output Matching ...................................................... 14

VGA Operation .......................................................................... 15

Modulated Gain Mode .............................................................. 15

AGC Operation .......................................................................... 15

Modifying the AGC Setpoint .................................................... 16

Evaluation Board ........................................................................ 19

Characterization Setup and Methods...................................... 20

Outline Dimensions ....................................................................... 21

Ordering Guide .......................................................................... 21

7/05—Rev. 0 to Rev. A

Changes to Format ............................................................. Universal

Changes to General Description .................................................... 1

Changes to Table 1............................................................................ 3

Changes to Table 3............................................................................ 6

Changes to Figure 8.......................................................................... 7

Changes to Figure 9, Figure 12, and Figure 14 ............................. 8

Changes to Input and Output Interfaces Section....................... 11

Changes to Output Centering Section and Figure 31................ 12

Changes to RMS Detection Section .............................................13

Changes to Figure 32, Table 4, and Table 5 ................................. 14

Changes to Figure 33, Figure 34, and

AGC Operation Section................................................................. 15

Changes to the Modifying the AGC Set Point Section.............. 16

Changes to Figure 38...................................................................... 17

Changes to Figure 42...................................................................... 19

Changes to Table 7.......................................................................... 20

Moved Table 7 to Page ................................................................... 20

Moved Characterization Setup and Methods Section to Page . 20

Moved Figure 45 to Page ............................................................... 20

Changes to Ordering Guide.......................................................... 21

Updated Outline Dimensions....................................................... 21

10/01—Revision 0: Initial Version

Rev. A | Page 2 of 24

AD8367

SPECIFICATIONS

VS = 5 V, TA = 25°C, system impedance ZO = 200 Ω, V

Table 1.

Parameter Conditions Min Typ Max Unit

OVERALL FUNCTION

Frequency Range LF 500 MHz GAIN Range 45 dB

INPUT STAGE Pins INPT and ICOM

Maximum Input To avoid input overload 700 mV p-p Input Resistance From INPT to ICOM 175 200 225 Ω

GAIN CONTROL INTERFACE Pin GAIN

Scaling Factor V V

= 5 V, 50 mV ≤ V

MODE

= 0 V, 50 mV ≤ V

MODE

Gain Law Conformance 100 mV ≤ V Maximum Gain V Minimum Gain V V

Step Response From 0 dB to 30 dB 300 ns

GAIN

= 0.95 V +42.5 dB

GAIN

= 0.05 V −2.5 dB

GAIN

From 30 dB to 0 dB 300 ns Small Signal Bandwidth V

= 0.5 V 5 MHz

GAIN

OUTPUT STAGE Pin VOUT

Maximum Output Voltage Swing RL = 1 kΩ 4.3 V p-p R

= 200 Ω 3.5 V p-p

L

Output Source Resistance Series resistance of output buffer 50 Ω Output Centering Voltage

1

V

SQUARE LAW DETECTOR Pin DETO

Output Set Point 354 mV rms AGC Small Signal Response Time C

= 100 pF, 6 dB gain step 1 μs

AGC

POWER INTERFACE Pins VPSI, VPSO, ICOM, and OCOM

Supply Voltage 2.7 5.5 V Total Supply Current

ENBL high, maximum gain, R (includes load current)

Disable Current vs. Temperature ENBL low 1.3 1.6 mA

−40°C ≤ TA ≤ +85°C 1.8 mA MODE CONTROL INTERFACE Pin MODE

Mode LO Threshold Device in negative slope mode of operation 1.2 V Mode HI Threshold Device in positive slope mode of operation 1.4 V

ENABLE INTERFACE Pin ENBL

Enable Threshold 2.5 V Enable Response Time

Time delay following LO to HI transition until

device meets full specifications. Enable Input Bias Current ENBL at 5 V 27 μA ENBL at 0 V 32 nA f = 70 MHz Gain Maximum gain +42.5 dB Minimum gain −3.7 dB Gain Scaling Factor 19.9 mV/dB Gain Intercept −5.6 dB Noise Figure Maximum gain 6.2 dB Output IP3 f1 = 70 MHz, f2 = 71 MHz, V

29.5 dBV rms Output 1 dB Compression Point V

= 0.5 V 8.5 dBm

GAIN

1.5 dBV rms

= 5 V, f = 10 MHz, unless otherwise noted.

MODE

≤ 950 mV +20 mV/dB

GAIN

≤ 950 mV −20 mV/dB

GAIN

≤ 900 mV ±0.2 dB

GAIN

/2 V

S

= 200 Ω

L

26 30 mA

1.5 μs

= 0.5 V 36.5 dBm

GAIN

Rev. A | Page 3 of 24

AD8367

Parameter Conditions Min Typ Max Unit

f = 140 MHz

Gain Maximum gain +43.5 dB Minimum gain −3.6 dB Gain Scaling Factor 19.7 mV/dB Gain Intercept −5.3 dB Noise Figure Maximum gain 7.4 dB Output IP3 f1 = 140 MHz, f2 = 141 MHz, V

25.7 dBV rms Output 1 dB Compression Point V

= 0.5 V 8.4 dBm

GAIN

1.4 dBV rms

f = 190 MHz

Gain Maximum gain +43.5 dB Minimum gain −3.8 dB Gain Scaling Factor 19.6 mV/dB Gain Intercept −5.3 dB Noise Figure Maximum gain 7.5 dB Output IP3 f1 = 190 MHz, f2 = 191 MHz, V

23.9 dBV rms Output 1 dB Compression Point V

= 0.5 V 8.4 dBm

GAIN

1.4 dBV rms

f = 240 MHz

Gain Maximum gain +43 dB Minimum gain −4.1 dB Gain Scaling Factor 19.7 mV/dB Gain Intercept −5.2 dB Noise Figure Maximum gain 7.6 dB Output IP3 f1 = 240 MHz, f2 = 241 MHz, V

22.2 dBV rms Output 1 dB Compression Point V

= 0.5 V 8.1 dBm

GAIN

1.1 dBV rms

1

The output dc centering voltage is normally set at VS/2 and can be adjusted by applying a voltage to DECL.

= 0.5 V 32.7 dBm

GAIN

= 0.5 V 30.9 dBm

GAIN

= 0.5 V 29.2 dBm

GAIN

Rev. A | Page 4 of 24

AD8367

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

Supply Voltage VPSO, VPSI 5.5 V ENBL Voltage VS + 200 mV MODE Select Voltage VS + 200 mV V

Control Voltage 1.2 V

GAIN

Input Voltage ±600 mV Internal Power Dissipation 250 mW θ

JA

Maximum Junction Temperature 125°C Operating Temperature Range −40°C to +85°C Storage Temperature Range −65°C to +150°C Lead Temperature Range

(Soldering 60 sec)

150°C/W

300°C

ESD 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 this product 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.

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.

Rev. A | Page 5 of 24

AD8367

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

ICOM ENBL

INPT

MODE

GAIN

DETO

ICOM

1 2 3

AD8367

4

TOP VIEW

(Not to Scale)

5 6 7

14 13 12 11 10

9 8

ICOM HPFL VPSI VPSO VOUT DECL OCOM

02710-002

Figure 2. Pin Configuration

Table 3. Pin Function Descriptions

Pin No. Mnemonic Description

1, 7, 14 ICOM Signal Common. Connect to low impedance ground. 2 ENBL A HI Activates the Device. 3 INPT Signal Input. 200 Ω to ground. 4 MODE Gain Direction Control. HI for positive slope; LO for negative slope. 5 GAIN Gain Control Voltage Input. 6 DETO Detector Output. Provides output current for RSSI function and AGC control. 8 OCOM Power Common. Connect to low impedance ground. 9 DECL Output Centering Loop Decoupling Pin. 10 VOUT Signal Output. To be externally ac-coupled to load. 11 VPSO

Positive Supply Voltage. 2.7 V to 5.5 V. VPSI and VPSO are tied together internally with back-to-back

PN junctions. They should be tied together externally and properly bypassed. 12 VPSI Positive Supply Voltage. 2.7 V to 5.5 V. 13 HPFL High-Pass Filter Connection. A capacitor to ground sets the corner frequency of the output offset control loop.

Rev. A | Page 6 of 24

AD8367

TYPICAL PERFORMANCE CHARACTERISTICS

VS = 5 V, TA = 25°C, system impedance ZO = 200 Ω, V

50

1V

40

30

20

GAIN (dB)

10

0

0.9V

0.8V

0.7V

0.6V

0.5V

0.4V

0.3V

0.2V

0.1V

= 5 V, unless otherwise noted.

MODE

NOISE FIGURE (dB)

10

+85°C

9

+25°C

8

–40°C

7

6

5

–10

10 100 1000

FREQUENCY (MHz)

Figure 3. Gain vs. Frequency for Values of V

45

40

35

30

MODE = 0V 10MHz 70MHz 140MHz 240MHz

–40°C

+25°C +85°C

GAIN (dB)

25

20

GAIN (dB)

15

10

–5

45

40

35

30

25

20

15

10

5

0

–5

0 1.00.90.80.70.60.50.40.30.20.1

5

0

0 1.00.90.80.70.60.50.40.30.20.1

MODE = 5V

10MHz

70MHz 140MHz 240MHz

Figure 4. Gain vs. V

V

(V)

GAIN

(Mode LO and Mode HI)

GAIN

V

(V)

GAIN

02710-003

02710-004

2.0

1.6

1.2

0.8

0.4

0

–0.4

–0.8

–1.2

–1.6

–2.0

Figure 5. Gain Conformance at 70 MHz for T = −40°C, +25°C, and +85°C

LINEARITY ERROR (dB)

02710-005

4

70 25023021019017015013011090

FREQUENCY (MHz)

Figure 6. NF (re 200 Ω) vs. Frequency at Maximum Gain

60

50

40

30

20

NOISE FIGURE (dB)

10

0

OIP3 (dBm)

0 1.00.90.80.70.60.50.40.30.20.1

Figure 7. NF (re 200 Ω) vs. V

40

35

30

25

20

15

10

5

0

0 1.00.90.80.70.60.50.40.30.20.1

V

(V)

GAIN

140MHz

V

(V)

GAIN

Figure 8. OIP3 vs. V

at 70 MHz

GAIN

70MHz

240MHz

GAIN

02710-006

`

02710-007

10MHz

02710-008

Rev. A | Page 7 of 24

AD8367

40

33

0

35

30

25

20

OIP3 (dBm re 200Ω)

15

10

10 1000100

Figure 9. OIP3 vs. Frequency for V

4

2

0

–2

–4

FREQUENCY (MHz)

= 500 mV

GAIN

140MHz

10MHz

200MHz

70MHz

28

23

18

OIP3 (dBV rms)

13

8

02710-009

3

11

)

Ω

9

7

5

3

–10

–20

–30

–40

–50

OUTPUT IMD3 (dBc)

–60

–70

–80

10MHz

0 1.00.90.80.70.60.50.40.30.20.1

Figure 12. IMD3 vs. Gain (V

4

2

0

–2

–4

140MHz

V

(V)

GAIN

= 1 V p-p Composite)

OUT

240MHz

70MHz

02710-012

11

)

Ω

9

7

5

3

–6

OUTPUT 1dB COMPRESSION (dBV rms)

–8

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Figure 10. Output P1dB vs. V

5

4

3

2

1

0

–1

–2

–3

OUTPUT 1dB COMPRESSION (dBV rms)

–4

–5

10 100 1000

Figure 11. Output P1dB vs. Frequency at V

V

(V)

GAIN

FREQUENCY (MHz)

GAIN

= 500 mV

1

OUTPUT 1dB COMPRESSION (dBm re 200

02710-010

–1

–6

OUTPUT 1dB COMPRESSION (dBV rms)

–8

2.5 5.55.04.54.03.53.0 VS (V)

1

OUTPUT 1dB COMPRESSION (dBm re 200

02710-013

–1

Figure 13. Output Compression Point vs. Supply Voltage at 70 MHz,

= 500 mV

V

GAIN

12

)

Ω

11

10

9

8

7

6

5

4

3

OUTPUT 1dB COMPRESSION (dBm re 200

02710-011

2

40

35

)

30

Ω

25

20

15

10

OUTPUT IP3 (dBm re 200

5

0

2.5 5.55.04.54.03.53.0 VS (V)

33

28

23

18

13

8

OUTPUT IP3 (dBV rms)

3

–2

02710-014

–7

Figure 14. Output Third-Order Intercept vs. Supply Voltage at 70 MHz,

= 500 mV

V

GAIN

Rev. A | Page 8 of 24

Analog Devices AD8367 Service Manual

FEATURES

APPLICATIONS

GENERAL DESCRIPTION

FUNCTIONAL BLOCK DIAGRAM

TABLE OF CONTENTS

REVISION HISTORY

SPECIFICATIONS

ABSOLUTE MAXIMUM RATINGS

ESD CAUTION

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

TYPICAL PERFORMANCE CHARACTERISTICS