ANALOG DEVICES AD8313 Service Manual

0.1 GHz to 2.5 GHz 70 dB

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FEATURES

Wide bandwidth: 0.1 GHz to 2.5 GHz min High dynamic range: 70 dB to ±3.0 dB High accuracy: ±1.0 dB over 65 dB range (@ 1.9 GHz) Fast response: 40 ns full-scale typical Controller mode with error output Scaling stable over supply and temperature Wide supply range: 2.7 V to 5.5 V Low power: 40 mW at 3 V Power-down feature: 60 mW at 3 V Complete and easy to use

APPLICATIONS

RF transmitter power amplifier setpoint control and

level monitoring

Logarithmic amplifier for RSSI measurement cellular

base stations, radio link, radar

GENERAL DESCRIPTION

The AD8313 is a complete multistage demodulating logarithmic amplifier that can accurately convert an RF signal at its differential input to an equivalent decibel-scaled value at its dc output. The AD8313 maintains a high degree of log conformance for signal frequencies from 0.1 GHz to 2.5 GHz and is useful over the range of 10 MHz to 3.5 GHz. The nominal input dynamic range is –65 dBm to 0 dBm (re: 50 Ω), and the sensitivity can be increased by 6 dB or more with a narrow-band input impedance matching network or a balun. Application is straightforward, requiring only a single supply of 2.7 V to 5.5 V and the addition of a suitable input and supply decoupling. Operating on a 3 V supply, its 13.7 mA consumption (for T A power-down feature is provided; the input is taken high to initiate a low current (20 µA) sleep mode, with a threshold at half the supply voltage.

The AD8313 uses a cascade of eight amplifier/limiter cells, each having a nominal gain of 8 dB and a −3 dB bandwidth of

3.5 GHz. This produces a total midband gain of 64 dB. At each amplifier output, a detector (rectifier) cell is used to convert the RF signal to baseband form; a ninth detector cell is placed directly at the input of the AD8313. The current-mode outputs of these cells are summed to generate a piecewise linear approximation to the logarithmic function. They are converted to a low impedance voltage-mode output by a transresistance stage, which also acts as a low-pass filter.

= 25°C) is only 41 mW.

A

Logarithmic Detector/Controller

AD8313

FUNCTIONAL BLOCK DIAGRAM

NINE DETECTOR CELLS

++ ++

1

VPOS

2

INHI

INLO

VPOS

3

4

8dB8dB

EIGHT 8dB 3.5GHz AMPLIFIER STAGES

AD8313

SLOPE

CONTROL

8dB 8dB

BAND GAP

REFERENCE

Figure 1.

When used as a log amplifier, scaling is determined by a separate feedback interface (a transconductance stage) that sets the slope to approximately 18 mV/dB; used as a controller, this stage accepts the setpoint input. The logarithmic intercept is positioned to nearly −100 dBm, and the output runs from about 0.45 V dc at −73 dBm input to 1.75 V dc at 0 dBm input. The scale and intercept are supply- and temperature-stable.

The AD8313 is fabricated on Analog Devices’ advanced 25 GHz silicon bipolar IC process and is available in an 8-lead MSOP package. The operating temperature range is −40°C to +85°C. An evaluation board is available.

2.0 FREQUENCY = 1.9GHz

1.8

1.6

1.4

1.2

1.0

0.8

0.6

OUTPUT VOLTAGE (V DC)

0.4

0.2

0

–70 –60 –50 –40 –30 –20 –10

–80

Figure 2. Typical Logarithmic Response and Error vs. Input Amplitude

INPUT AMPLITUDE (dBm)

+

I→V

LP

INTERCEPT

CONTROL

GAIN BIAS

C

V→I

8

VOUT

INT

7

VSET

6

COMM

5

PWDN

01085-C-001

5

4 3

2

1

0 –1 –2

OUTPUT ERROR (dB)

–3

–

4

–5

0

01085-C-002

Rev. D

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. 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.

AD8313

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TABLE OF CONTENTS

Specifications..................................................................................... 3

Input Coupling ........................................................................... 16

Absolute Maximum Ratings............................................................ 6

ESD Caution.................................................................................. 6

Pin Configurations and Function Description............................. 7

Typical Performance Characteristics............................................. 8

Circuit Description......................................................................... 11

Interfaces ..........................................................................................13

Power-Down Interface, PWDN ................................................13

Signal Inputs, INHI, INLO ........................................................ 13

Logarithmic/Error Output, VOUT .......................................... 13

Setpoint Interface, VSET............................................................ 14

Applications..................................................................................... 15

Basic Connections for Log (RSSI) Mode................................. 15

Operating in Controller Mode ................................................. 15

REVISION HISTORY

6/04—Data Sheet Changed from Rev. C to Rev. D

Updated Evaluation Board Section .............................................. 21

Narrow-Band LC Matching Example at 100 MHz ................ 16

Adjusting the Log Slope............................................................. 18

Increasing Output Current........................................................ 19

Effect of Waveform Type on Intercept..................................... 19

Evaluation Board ............................................................................ 20

Schematic and Layout................................................................ 20

General Operation ..................................................................... 20

Using the AD8009 Operational Amplifier.............................. 20

Var yi n g t he L og ar i t hm ic S lo p e................................................. 20

Operating in Controller Mode ................................................. 20

RF Burst Response ..................................................................... 20

Outline Dimensions....................................................................... 24

Ordering Guide .......................................................................... 24

2/03—Data Sheet changed from Rev. B to Rev. C TPCs and F

Edits to SPECIFICATIONS............................................................. 2

Updated ESD CAUTION ................................................................ 4

Updated OUTLINE DIMENSIONS .............................................. 7

8/99—Data Sheet changed from Rev. A to Rev. B

5/99—Data Sheet changed from Rev. 0 to Rev. A

8/98—Revision 0: Initial Version

igures Renumbered........................................Universal

Rev. D | Page 2 of 24

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SPECIFICATIONS

TA = 25°C, VS = 5 V1, RL 10 kΩ, unless otherwise noted.

Table 1.

Parameter Conditions Min

SIGNAL INPUT INTERFACE

Specified Frequency Range 0.1 2.5 GHz DC Common-Mode Voltage V Input Bias Currents 10 µA Input Impedance fRF < 100 MHz

LOG (RSSI) MODE

100 MHz

2.7 V ≤ VS ≤ 5.5 V, −40°C ≤ T ≤ +85°C

900 MHz

2.7 V ≤ VS ≤ 5.5 V, –40°C ≤ T ≤ +85°C

1.9 GHz7 Nominal conditions

2.7 V ≤ VS ≤ 5.5 V, –40°C ≤ T ≤ +85°C

5

±3 dB Dynamic Range

Range Center −31.5 dBm ±1 dB Dynamic Range 56 dB Slope 17 19 21 mV/dB Intercept −96 −88 −80 dBm

±3 dB Dynamic Range 51 64 dB

Range Center −31 dBm ±1 dB Dynamic Range 55 dB Slope 16 19 22 mV/dB Intercept −99 −89 −75 dBm Temperature Sensitivity PIN = −10 dBm −0.022 dB/°C

5

±3 dB Dynamic Range 60 69 dB

Range Center −32.5 dBm ±1 dB Dynamic Range 62 dB Slope 15.5 18 20.5 mV/dB Intercept −105 −93 −81 dBm

±3 dB Dynamic Range 55.5 68.5 dB

Range Center –32.75 dBm ±1 dB Dynamic Range 61 dB Slope 15 18 21 mV/dB Intercept –110 –95 –80 dBm Temperature Sensitivity PIN = –10 dBm –0.019 dB/°C

±3 dB Dynamic Range 52 73 dB

Range Center –36.5 dBm ±1 dB Dynamic Range 62 dB Slope 15 17.5 20.5 mV/dB Intercept –115 –100 –85 dBm

±3 dB Dynamic Range 50 73 dB

Range Center –36.5 dBm ±1 dB Dynamic Range 60 dB Slope 14 17.5 21.5 mV/dB Intercept –125 –101 –78 dBm Temperature Sensitivity PIN = –10 dBm –0.019 dB/°C

6

Sinusoidal, input termination configuration

wn in Figure 29

sho Nominal conditions

53.5 65 dB

Nominal conditions

3

2

900||1.1 Ω||pF

Typ Max

– 0.75 V

POS

2

Unit

4

Rev. D | Page 3 of 24

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Parameter Conditions Min

2.7 V ≤ VS ≤ 5.5 V, –40°C ≤ T ≤ +85°C

CONTROL MODE

VOUT INTERFACE

VSET INTERFACE

POWER-DOWN INTERFACE PWDN Threshold V

PWDN = VS <1 µA POWER SUPPLY

2.7 V ≤VS ≤ 3.3 V, –40°C ≤ T ≤ +85°C 20 50 µA

7

2.5 GHz ±3 dB Dynamic Range 48 66 dB

Range Center –34 dBm ±1 dB Dynamic Range 46 dB Slope 16 20 25 mV/dB Intercept –111 –92 –72 dBm

±3 dB Dynamic Range 47 68 dB

Range Center –34.5 dBm ±1 dB Dynamic Range 46 dB Slope 14.5 20 25 mV/dB Intercept –128 –92 –56 dBm Temperature Sensitivity PIN =–10 dBm –0.040 dB/°C

5

3.5 GHz ±3 dB Dynamic Range 43 dB ±1 dB Dynamic Range 35 dB Slope 24 mV/dB Intercept –65 dBm

Controller Sensitivity f = 900 MHz 23 V/dB Low Frequency Gain VSET to VOUT8 84 dB Open-Loop Corner Frequency VSET to VOUT Open-Loop Slew Rate f = 900 MHz 2.5 V/µs VSET Delay Time 150 ns

Current Drive Capability

Source Current 400 µA Sink Current 10 mA

Minimum Output Voltage Open-loop 50 mV Maximum Output Voltage Open-loop V Output Noise Spectral Density PIN = –60 dBm, f P Small Signal Response Time PIN = –60 dBm to –57 dBm, 10% to 90% 40 60 ns Large Signal Response Time PIN = No signal to 0 dBm; settled to 0.5 dB 110 160 ns

Input Voltage Range 0 V Input Impedance 18||1 kΩ||pF4

Power-Up Response Time

PWDN Input Bias Current PWDN = 0 V 5 µA

Operating Range 2.7 5.5 V Powered-Up Current 13.7 15.5 mA

4.5 V ≤VS ≤ 5.5 V, –40°C ≤ T ≤ +85°C 18.5 mA

2.7 V ≤VS ≤ 3.3 V, –40°C ≤ T ≤ +85°C 18.5 mA

Powered-Down Current 4.5 V ≤VS ≤ 5.5 V, –40°C ≤ T ≤ +85°C 50 150 µA

Nominal conditions

8

= 100 Hz 2.0 µV/√Hz

SPOT

= –60 dBm, f

IN

Time delay following high to low transition

til device meets full specifications.

un

= 10 MHz 1.3 µV/√Hz

SPOT

2

700 Hz

1.8 µs

Typ Max

– 0.1 V

POS

/2 V

POS

2

Unit

V

Rev. D | Page 4 of 24

AD8313

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1

Except where otherwise noted; performance at VS = 3 V is equivalent to 5 V operation.

2

Minimum and maximum specified limits on parameters that are guaranteed but not tested are 6 sigma values.

3

Input impedance shown over frequency range in Figure 26.

4

Double vertical bars (||) denote “in parallel with.”

5

Linear regression calculation for error curve taken from –40 dBm to –10 dBm for all parameters.

6

Dynamic range refers to range over which the linearity error remains within the stated bound.

7

Linear regression calculation for error curve taken from –60 dBm to –5 dBm for 3 dB dynamic range. All other regressions taken from –40 dBm to –10 dBm.

8

AC response shown in Figure 12.

Rev. D | Page 5 of 24

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ABSOLUTE MAXIMUM RATINGS

Table 2.

Supply Voltage V VOUT, VSET, PWDN 0 V, VPOS Input Power Differential (re: 50 Ω, 5.5 V) 25 dBm Input Power Single-Ended (re: 50 Ω, 5.5 V) 19 dBm Internal Power Dissipation 200 mW θ

JA

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

S

5.5 V

200°C/W

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. D | Page 6 of 24

AD8313

V

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PIN CONFIGURATIONS AND FUNCTION DESCRIPTION

POS

1

INHI

INLO

POS

AD8313

2

TOP VIEW

3

(Not to Scale)

4

Figure 3. Pin Configuration

Table 3. Pin Function Descriptions

Pin No. Mnemonic Description

1, 4 VPOS Positive Supply Voltage (VPOS), 2.7 V to 5.5 V. 2 INHI Noninverting Input. This input should be ac-coupled. 3 INLO Inverting Input. This input should be ac-coupled. 5 PWDN Connect Pin to Ground for Normal Operating Mode. Connect this pin to the supply for power-down mode. 6 COMM Device Common. 7 VSET Setpoint Input for Operation in Controller Mode. To operate in RSSI mode, short VSET and VOUT. 8 VOUT Logarithmic/Error Output.

VOUT

8

VSET

7 6

COMM PWDN

5

01085-C-003

Rev. D | Page 7 of 24

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TYPICAL PERFORMANCE CHARACTERISTICS

TA = 25°C, VS = 5 V, RL input match shown in Figure 29, unless otherwise noted.

2.0

1.8

1.6

1.4

1.2

(V)

1.0

OUT

V

0.8

0.6

0.4

0.2

0

–70

6

4

2

0

ERROR (dB)

–2

1.9GHz

–4

–6

–70 10–60

1.9GHz

900MHz

–60 –50 –40 –30 –20 –10 0 10

INPUT AMPLITUDE (dBm)

Figure 4. V

900MHz

100MHz

2.5GHz

–50 –40 –30 –20 –10

INPUT AMPLITUDE (dBm)

2.5GHz

vs. Input Amplitude

OUT

2.5GHz 100MHz

1.9GHz

100MHz

900MHz

0

01085-C-004

01085-C-005

2.0

1.8

1.6

1.4

1.2

(V)

1.0

OUT

V

0.8

0.6

0.4 SLOPE AND INTERCEPT NORMALIZED AT +25°C

0.2 AND APPLIED TO –40°C AND +85°C

0

–60 –50 –40 –30 –20 –10 0 10

–70

Figure 7. V

and Log Conformance vs. Input Amplitude at 900 MHz for

OUT

INPUT AMPLITUDE (dBm)

Multiple Temperatures

2.0

1.8

1.6 –40°C

1.4

1.2

(V)

+25°C

1.0

OUT

V

0.8

+85°C

0.6

0.4

SLOPE AND INTERCEPT NORMALIZED AT +25°C

0.2

AND APPLIED TO –40°C AND +85°C

0

–60 –50 –40 –30 –20 –10 0 10

–70

INPUT AMPLITUDE (dBm)

–40°C

+25°C

+85°C

5

4 3

2

1

0 –1 –2 –3

–4 –5

5

4 3

2

1

0 –1 –2 –3

–4 –5

ERROR (dB)

01-85-C-007

ERROR (dB)

01085-C-008

Figure 5. Log Conformance vs. Input Amplitude

2.0

1.8

1.6

1.4

1.2

(V)

1.0

OUT

V

0.8

0.6

0.4 SLOPE AND INTERCEPT NORMALIZED AT +25°C

0.2 AND APPLIED TO –40°C AND +85°C

0

–60 –50 –40 –30 –20 –10 0 10

–70

Figure 6. V

OUT

INPUT AMPLITUDE (dBm)

and Log Conformance vs. Input Amplitude at 100 MHz for

Multiple Temperatures

Figure 8. V

(V)

V

OUT

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

–40°C +25°C

+85°C

5

4 3

2

1

0 –1 –2 –3

–4 –5

ERROR (dB)

01085-C-006

Figure 9. V

and Log Conformance vs. Input Amplitude at 1.9 GHz for

OUT

Multiple Temperatures

–40°C

+25°C

SLOPE AND INTERCEPT NORMALIZED AT +25°C AND APPLIED TO –40°C AND +85°C

+85°C

0

–60 –50 –40 –30 –20 –10 0 10

–70

and Log Conformance vs. Input Amplitude at 2.5 GHz for

OUT

INPUT AMPLITUDE (dBm)

Multiple Temperatures

Rev. D | Page 8 of 24

5

4 3

2

1

0 –1 –2 –3

–4 –5

ERROR (dB)

01085-C-009