Analog Devices AD8313 Datasheet

0.1 GHz–2.5 GHz, 70 dB

a

FEATURES
Wide Bandwidth: 0.1 GHz to 2.5 GHz Min
High Dynamic Range: 70 dB to ⴞ3.0 dB
High Accuracy: ⴞ1.0 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 ␮W 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

PRODUCT DESCRIPTION

The AD8313 is a complete multistage demodulating logarith­mic amplifier, capable of accurately converting 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 balun. Application is
straightforward, requiring only a single supply of 2.7 V–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

+25°C) amounts to only 41 mW. 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, for 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, and converted to a low impedance voltage­mode output by a transresistance stage, which also acts as a low­pass filter.

=

A

Logarithmic Detector/Controller

AD8313

FUNCTIONAL BLOCK DIAGRAM

NINE DETECTOR CELLS

++ ++

VPOS

INHI

INLO

VPOS

8dB8dB

EIGHT 8dB 3.5GHz AMPLIFIER STAGES

AD8313

SLOPE

CONTROL

8dB 8dB

BAND-GAP

REFERENCE

When used as a log amp, the 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 a 8-lead

µSOIC 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 – Volts DC

0.4

0.2

0

–70 –60 –50 –40 –30 –20 –10

–80

INPUT AMPLITUDE – dBm

Figure 1. Typical Logarithmic Response and Error vs.
Input Amplitude

+

IvV

LP

INTERCEPT

CONTROL

GAIN
BIAS

C

INT

VvI

VOUT

VSET

COMM

PWDN

5

4
3

2

1

0
–1
–2

OUTPUT ERROR – dB

–3

–4
–5

0

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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] World Wide Web Site: http://www.analog.com
Fax: [phone] © Analog Devices, Inc., 1999

AD8313–SPECIFICATIONS

(@ TA = +25ⴗC, VS = +5.0 V1, R

Parameter Conditions Min

≥ 10 k⍀ unless otherwise noted)

L

2

Typ Max

2

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 Sinusoidal, input termination configuration shown in Figure 27.

100 MHz

5

±3 dB Dynamic Range

6

Nominal Conditions

3

53.5 65 dB

– 0.75 V

POS

900储1.1 Ω储pF

Range Center –31.5 dBm

±1 dB Dynamic Range 56 dB

Slope 17 19 21 mV/dB
Intercept –96 –88 –80 dBm

+2.7 V ≤ V

≤ +5.5 V, –40°C ≤ T ≤ +85°C

S

±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 P

900 MHz

5

= –10 dBm –0.022 dB/°C

IN

Nominal Conditions

±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

+2.7 V ≤ V

≤ +5.5 V, –40°C ≤ T ≤ +85°C

S

±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 P

1.9 GHz

7

= –10 dBm –0.019 dB/°C

IN

Nominal Conditions

±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

+2.7 V ≤ V

≤ +5.5 V, –40°C ≤ T ≤ +85°C

S

±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 P

2.5 GHz

7

= –10 dBm –0.019 dB/°C

IN

Nominal Conditions

±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

+2.7 V ≤ V

≤ +5.5 V, –40°C ≤ T ≤ +85°C

S

±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 P

= –10 dBm –0.040 dB/°C

IN

Units

4

–2–

REV. B

AD8313

Parameter Conditions Min

3.5 GHz

5

2

Typ Max

±3 dB Dynamic Range 43 dB
±1 dB Dynamic Range 35 dB

Slope 24 mV/dB
Intercept –65 dBm

CONTROL MODE

Controller Sensitivity f = 900 MHz 23 V/dB
Low Frequency Gain VSET to VOUT
Open-Loop Corner Frequency VSET to VOUT

8

8

84 dB
700 Hz

Open-Loop Slew Rate f = 900 MHz 2.5 V/µs

VSET Delay Time 150 ns

VOUT INTERFACE

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 P

Small Signal Response Time P

= –60 dBm, f

IN

= –60 dBm, f

P

IN

= –60 dBm to –57 dBm, 10% to 90% 40 60 ns

IN

= 100 Hz 2.0 µV/√Hz

SPOT

= 10 MHz 1.3 µV/√Hz

SPOT

– 0.1 V

POS

Large Signal Response Time PIN = No Signal to 0 dBm, Settled to 0.5 dB 110 160 ns

VSET INTERFACE

Input Voltage Range 0 V

Input Impedance 18k储1 Ω储pF

POWER-DOWN INTERFACE

PWDN Threshold V

/2 V

POS

Power-Up Response Time Time delay following HI to LO transition

until device meets full specifications. 1.8 µs

PWDN Input Bias Current PWDN = 0 V 5 µA

PWDN = V

S

<1 µA

POWER SUPPLY

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

+4.5 V ≤ V
+2.7 V ≤ V

Powered Down Current +4.5 V ≤ V

≤ +5.5 V, –40°C ≤ T ≤ +85°C 18.5 mA

S

≤ +3.3 V, –40°C ≤ T ≤ +85°C 18.5 mA

S

≤ +5.5 V, –40°C ≤ T ≤ +85°C 50 150 µA

S

+2.7 V ≤ VS ≤ +3.3 V, –40°C ≤ T ≤ +85°C2050µA

NOTES

1

Except where otherwise noted, performance at VS = +3.0 V is equivalent to +5.0 V operation.

2

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

3

Input impedance shown over frequency range in Figure 24.

4

Double slashes (储) 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 10.

Specifications subject to change without notice.

2

POS

Units

V

–3–REV. B

AD8313

WARNING!

ESD SENSITIVE DEVICE

ABSOLUTE MAXIMUM RATINGS*

Supply Voltage VS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5 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

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200°C/W

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) . . . . . . . . +300°C

*Stresses above those listed under Absolute Maximum Ratings may cause perma-

nent 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 effect device reliability.

PIN CONFIGURATION

VPOS

INHI

INLO

VPOS

1

2

AD8313

TOP VIEW

3

(Not to Scale)

4

8

7

6

5

VOUT
VSET
COMM
PWDN

ORDERING GUIDE

PIN FUNCTION DESCRIPTIONS

Pin Name 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 operat-

ing mode. Connect pin to 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.

Temperature Package Package Brand

Model Range Descriptions Option Code

AD8313ARM –40°C to +85°C 8-Lead µSOIC RM-08 J1A
AD8313ARM-REEL –40°C to +85°C 13” Tape and Reel RM-08 J1A
AD8313ARM-REEL7 –40°C to +85°C 7” Tape and Reel RM-08 J1A

AD8313-EVAL Evaluation Board

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 AD8313 features proprietary ESD protection circuitry, permanent damage may occur on
devices subjected to high energy [>250 V HBM] electrostatic discharges. Therefore, proper ESD
precautions are recommended to avoid performance degradation or loss of functionality.

–4–

REV. B

Typical Performance Characteristics–

AD8313

2.0
VS = +5V

1.8

INPUT MATCH SHOWN IN FIGURE 27

1.6

1.4

1.2

1.0

– Volts

OUT

0.8

V

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

Figure 2. V

900MHz

INPUT AMPLITUDE – dBm

OUT

100MHz

2.5GHz

–50 –40 –30 –20 –10

INPUT AMPLITUDE – dBm

2.5GHz

vs. Input Amplitude

VS = +5V
INPUT MATCH SHOWN IN FIGURE 27

2.5GHz

100MHz

100MHz

1.9GHz

Figure 3. Log Conformance vs. Input Amplitude

900MHz

0

2.0
VS = +5V

1.8

INPUT MATCH SHOWN IN FIGURE 27

1.6

1.4

1.2

1.0

– Volts

OUT

0.8

V

0.6

0.4

SLOPE AND INTERCEPT NORMALIZED AT +258C

0.2

AND APPLIED TO –408C AND +858C

0

–60 –50 –40 –30 –20 –10 0 10

–70

Figure 5. V

OUT

at 900 MHz; –40

2.0

VS = +5V

1.8

INPUT MATCH SHOWN IN FIGURE 27

1.6

–408C

1.4

1.2

+258C

1.0

– Volts

OUT

0.8

+858C

V

0.6

0.4

SLOPE AND INTERCEPT NORMALIZED AT +258C

0.2

AND APPLIED TO –408C AND +858C

0

–60 –50 –40 –30 –20 –10 0 10

–70

Figure 6. V

OUT

at 1.9 GHz; –40

5

4
3

2

–408C

+258C

+858C

INPUT AMPLITUDE – dBm

1

0
–1
–2
–3

–4
–5

ERROR – dB

and Log Conformance vs. Input Amplitude

°

C, +25°C and +85°C

5

4
3

2

1

0
–1

ERROR – dB

–2
–3

–4
–5

INPUT AMPLITUDE – dBm

and Log Conformance vs. Input Amplitude

°

C, +25°C and +85°C

2.0
VS = +5V

1.8

INPUT MATCH SHOWN IN FIGURE 27

1.6

1.4

1.2

1.0

– Volts

OUT

0.8

V

0.6

0.4

SLOPE AND INTERCEPT NORMALIZED AT +258C

0.2

AND APPLIED TO –408C AND +858C

0

–60 –50 –40 –30 –20 –10 0 10

–70

Figure 4. V

OUT

at 100 MHz; –40

5

4
3

2

–408C
+258C

+858C

INPUT AMPLITUDE – dBm

1

0
–1
–2
–3

–4
–5

ERROR – dB

and Log Conformance vs. Input Amplitude

°

C, +25°C and +85°C

– Volts

OUT

V

Figure 7. V
at 2.5 GHz; –40

–5–REV. B

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

VS = +5V
INPUT MATCH SHOWN IN FIGURE 27

–408C

+258C

SLOPE AND INTERCEPT
NORMALIZED AT +258C AND
APPLIED TO –408C AND +858C

+858C

0

–70

–60 –50 –40 –30 –20 –10 0 10

and Log Conformance vs. Input Amplitude

OUT

INPUT AMPLITUDE – dBm

°

C, +25°C and +85°C

5

4
3

2

1

0
–1
–2
–3

–4
–5

ERROR – dB