ANALOG DEVICES AD8312 Service Manual

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100 MHz−2.7 GHz, 45 dB

Preliminary Technical Data

FEATURES

Complete RF Detector Function
Typical Range : −45 dBm to 0 dBm re 50 Ω
Frequency Response from 100 MHz to 2.7 GHz
Temperature-Stable Linear-in-dB Response

Accurate to 2.7 GHz
Rapid Response: 70 ns to a 10 dB Step
Low Power: 12 mW at 2.7 V

APPLICATIONS

Cellular Handsets (GSM, CDMA, WCDMA)
RSSI and TSSI for Wireless Terminal Devices
Transmitter Power Measurement

PRODUCT DESCRIPTION

The AD8312 is a complete low cost subsystem for the
measurement of RF signals in the frequency range of 100 MHz
to 2.7 GHz, with a typical dynamic range of 45 dB, intended for
use in a wide variety of cellular handsets and other wireless
devices. It provides a wider dynamic range and better accuracy
than possible using discrete diode detectors. In particular, its
temperature stability is excellent over the full operating range of

−40°C to +85°C.

RF Log Detector

AD8312

Its high sensitivity allows measurement at low power levels, thus
reducing the amount of power that needs to be coupled to the
detector. It is essentially a voltage-responding device, with a
typical signal range of 1.25 mV to 224 mV rms or −45 dBm to 0
dBm re 50 Ω.

For convenience, the signal is internally ac-coupled, using a 5
pF capacitor to a load of 3 kΩ in shunt with 2 pF. This high­pass coupling, with a corner at approximately 16 MHz,
determines the lowest operating frequency. Thus, the source
may be dc-grounded.

The AD8312 output, called VOUT, increases from close to
ground to about 1.2 V as the input signal level increases from

1.25 mV to 224 mV. This output is intended for use in
measurement mode. Consult the Applications section of this
data sheet for information on use in this mode. A capacitor may
be connected between the VOUT and CFLT pins when it is
desirable to increase the time interval over which averaging of
the input waveform occurs.

The AD8312 is available in a 6-lead wafer-level chip scale
package, 1.0 mm x 1.5 mm, and consumes 4.5 mA from a 2.7 V
to 5.5 V supply.

FUNCTIONAL BLOCK DIAGRAM

PrA 10/29/2004

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.

Figure 1.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]
Fax: [phone] © 2004 Analog Devices, Inc. All rights reserved.

www.analog.com

AD8312 Preliminary Technical Data

TABLE OF CONTENTS

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

Absolute Maximum Ratings............................................................ 5

ESD Caution.................................................................................. 5

Pin Configuration and Function Descriptions............................. 6

Typical Performance Characteristics ............................................. 7

General Description ....................................................................... 10

Applications..................................................................................... 11

Basic Connections...................................................................... 11

Evaluation Board ........................................................................ 11

Outline Dimensions ....................................................................... 13

Ordering Guide .......................................................................... 13

Rev. PrA| Page 2 of 13

Preliminary Technical Data AD8312

SPECIFICATIONS

Table 1. VS = 3 V, C

Parameter Conditions Min Typ Max Unit

SIGNAL INPUT INTERFACE RFIN (Pin 6)

Specified Frequency Range
Input Voltage Range Internally AC-Coupled 1.25 224 mV rms

Equivalent Power Range 52.3 Ω External Termination –45 0 dBm

DC Resistance to COMM 100 kΩ

MEASUREMENT MODE

f = 0.1 GHz

Input Impedance 3020 || 1.35
± 1 dB Dynamic Range TA = +25°C

Maximum Input Level
Minimum Input Level
Slope 21.0 mV/dB

Intercept -50.4 dBm
Output Voltage - High Power In PIN = –10 dBm 0.85 V
Output Voltage - Low Power In PIN = –40 dBm 0.22 V
Temperature Sensitivity PIN = –10 dBm

f = 0.9 GHz

Input Impedance 903 || 1.16
± 1 dB Dynamic Range TA = +25°C

Maximum Input Level
Minimum Input Level
Slope 20.3 mV/dB

Intercept -51.4 dBm
Output Voltage - High Power In PIN = –10 dBm 0.839 V
Output Voltage - Low Power In PIN = –40 dBm 0.226 V
Temperature Sensitivity PIN = –10 dBm

f = 1.9 GHz

Input Impedance 440 || 1.14
± 1 dB Dynamic Range TA = +25°C

Maximum Input Level
Minimum Input Level
Slope 19.4 mV/dB

Intercept -51.8 dBm
Output Voltage - High Power In PIN = –10 dBm 0.815 V
Output Voltage - Low Power In PIN = –40 dBm 0.229 V
Temperature Sensitivity PIN = –10 dBm

= open, TA = 25°C, 52.3 Ω termination resistor at RFIN, unless otherwise noted.

FLT

0.1 2.7 GHz

VOUT (Pin 2) shorted to VSET (Pin 3), Sinusoidal
Input Signal

48 dB

−40°C < T

A

± 1 dB Error
± 1 dB Error

25°C ≤ T

−40°C ≤ T

≤ +85°C

A

A

< +85°C

≤ +25°C

40 dB
2 dBm

-46 dBm

- 0.0002

- 0.0050

50 dB

−40°C < T

A

± 1 dB Error
± 1 dB Error

25°C ≤ T
–40°C ≤ T

≤ +85°C

A

A

< +85°C

≤ +25°C

40 dB
2 dBm

-48 dBm

- 0.0036

-0.0010

46 dB

−40°C < T

A

± 1 dB Error
± 1 dB Error

25°C ≤ T
–40°C ≤ T

≤ +85°C

A

A

< +85°C

≤ +25°C

38 dB

-3 dBm

-49 dBm

-0.0044

-0.0027

Ω || pF

dB/°C
dB/°C

Ω || pF

dB/°C
dB/°C

Ω || pF

dB/°C
dB/°C

Rev. PrA| Page 3 of 13

AD8312 Preliminary Technical Data

Parameter Conditions Min Typ Max Unit

f = 2.5 GHz

Input Impedance 365 || 1.1

± 1 dB Dynamic Range TA = +25°C

Maximum Input Level

Minimum Input Level

−40°C < T

± 1 dB Error
± 1 dB Error

< +85°C

A

44 dB
36 dB

-4 dBm

-48 dBm

Slope 18.85 mV/dB

Intercept -51 dBm

Output Voltage - High Power In PIN = –10 dBm 0.774 V

Output Voltage - Low Power In PIN = –40 dBm 0.205 V

Temperature Sensitivity PIN = –10 dBm

25°C ≤ T
–40°C ≤ T

≤ +85°C

A

≤ +25°C

A

+0.0053

-0.0047

OUTPUT INTERFACE VOUT (Pin 2)

Minimum Output Voltage No Signal at RFIN, RL ≥ 10 kΩ 0.02 V

Maximum Output Voltage

1

RL ≥ 10 kΩ 2.2 V

General Limit 2.7 V ≤ VS ≤ 5.5 V VS – 1 V
Available Output Current Sourcing/Sinking 2/1 mA
Residual RF (at 2f) f = 0.1 GHz (Worst Condition) 100 µV
Output Noise RF Input = 2.2 GHz, –10 dBm, f

= 100 kHz,

NOISE

tbd

CFLT open
Fall Time Input Level = off to 0 dBm, 90% to 10% 120 ns
Rise Time Input Level = 0 dBm to off, 10% to 90% 85 ns

VSET INTERFACE VSET (Pin 3)

Input Resistance 10 kΩ
Bias Current Source RFIN = −10 dBm; VSET = 1.2V tbd

POWER INTERFACE VPOS (Pin 1)

Supply Voltage 2.7 3.0 5.5 V
Quiescent Current 4.2 mA

vs. Temperature

–40°C ≤ T

≤ +85°C

A

4.3 mA

1

Increased output possible when using an attenuator between VOUT and VSET to raise the slope.

Ω || pF

dB/°C
dB/°C

uV/√Hz

µA

Rev. PrA| Page 4 of 13