AD8361_P.PDF

2.5 GHz

True Power Detector

AD8361

Preliminary Technical Data

FEATURES

True Power Detection TM IC

RMS-to-DC Conversion

Modulation Independent Response

Excellent Temperature Stability

Greater Than 23 dB Input Range

Linear Response from DC to 2.5GHz

2.7 - 5.5 V Supply Voltage

Rapid Power-down to less than 1 uA

Single-ended Input, 200 W //1pF

SREF

VPOS

IREF

VRMS

RFIN

FLTR

PWDN

COMM

APPLICATIONS

Measurement of CDMA (IS-95) or Other Complex

Waveforms

Cellular Base Stations, Power Amplifiers, Radio Links

Transmitter Power Measurement

RSSI

8 Pin Micro-SO Package

PRODUCT DESCRIPTION

The AD8361 is a low power RMS-responding True Power

Detection TM IC for use in high frequency receiver and transmitter

signal chains. The device directly measures the RMS or True

Power level of signals up to 2.5GHz, covering the required

frequency range for cellular telephony, CATV, Wireless LAN and

many other applications. It is very easy to apply, requiring only a

single supply between 2.7 V and 5.5V, power supply decoupling

capacitor and an input coupling capacitor for many applications.

The output is linear responding DC output producing a conversion

gain of 7.4 V/V RMS . The averaging time constant can be modified

by adding an external filter capacitor.

measuring high crest factor (high peak-to-average ratio) signals,

such as CDMA and W-CDMA. It is also accurate for

measurement of most other complex modulation waveforms.

The AD8361 has three output reference modes to accommodate

a variety of analog-to-digital converter requirements: 1) ground

referenced, 2) internally referenced, offsetting the output 360

mV above ground , and 3) Vpos referenced, offsetting the output

to Vpos divided by 7.4.

The AD8361 is specified for operation from -30 o C to +85 o C and is

available in an 8 pin micro-SO package. It is fabricated on an

Analog Devices’ proprietary high fT silicon bipolar process.

The AD8361 is intended for True Power measurement of simple

and complex waveforms. The device is particular useful for

This information applies to a product under development. Its characteristics and specifications are subject to change without notice. Analog Devices assumes no obligation regarding

future manufacturing unless otherwise agreed to in writing.

True Power Detection is a trademark of Analog Devices Inc.

Analog Devices Confidential Information

Rev. PrA 8/18/99

AD8361-SPECIFICATIONS

(Unless otherwise noted, Vs=+3V; T A =25C; f RF =900MHz, Ground reference output mode)

Parameter

Condition

Min

Typ

Max

Units

(Input RFIN)

SIGNAL INPUT INTERFACE

Frequency Range

0.1

2.5

GHz

Maximum Input

Vs=+3V

390

mV RMS

Equivalent dBM re 50W

4.9

dBm

Vs =+5V

660

mV RMS

Input Impedance

200//1

W//pF

RMS Conversion

(Input RFIN to Output VRMS)

Conversion Gain

7.4

V/V RMS

+0.25dB Error Dynamic Range

CW input

+1dB Error Dynamic Range

CW input

+2dB Error Dynamic Range

CW input

CW input , Vs=+5V

Reference Mode Range

reduction

Internal Reference Mode

Supply Reference Mode, Vs=3.0V

Supply Reference Mode, Vs=5.0V

1.5

Deviation from CW response

5.5dB Peak to Average Ratio (IS95 reverse link)

0.2

12dB Pk to Ave Ratio (WCDMA 4 channels)

1.0

18dB Pk to Ave Ratio (WCDMA 15 channels)

TBD

Large Signal Response Time

No added capacitor on FLTR pin

usec

Output Reference

Calculated by a linear regression in linear output

range

Ground Reference Mode (GRM)

0V at SREF, Vs at IREF

Internal Reference Mode (IRM)

0V at SREF, IREF open

345

Supply Reference Mode (SRM)

0V at SREF and IREF

400

0V at SREF and IREF, Vs

Vs/7.5

ENABLE INTERFACE

ENBL HI Threshold

+2.7<Vs<+5.5V, -40C<T<+85C

Vs-0.5

ENBL LO Threshold

+2.7<Vs<+5.5V, -40C<T<+85C

0.1

Power-up Response Time

2pF at FLTR pin, 227 mV RMS at RFIN

100nF at FLTR pin, 227 mV RMS at RFIN

320

ENBL bias current

POWER SUPPLIES

Operating Range

-40C<T<-85C

+2.7

+5.5

Quiescent Current

200 mV RMS at RFIN, ENBLE input HI

GRM, 0 mV RMS at RFIN, ENBLE input LO

IRM, 0 mV RMS at RFIN, ENBLE input LO

SRM, 0 mV RMS at RFIN, ENBLE input LO

9.8*Vs

This information applies to a product under development. Its characteristics and specifications are subject to change without notice. Analog Devices assumes no obligation

regarding future manufacturing unless otherwise agreed to in writing. Patents pending. Rev PrA 8/18/99

Analog Devices Confidential Information

Absolute Max. Ratings

Supply Voltage

5.5

RF Input Power

TBD

dBm

Operating Temperature

-30

Deg. C

Storage Temperature

-65

150

Deg. C

AD8361 Pin Descriptions

NAME

DESCRIPTION

EQUIVALENT

CIRCUIT

VPOS

Supply voltage pin operational range 2.7 to 5.5 volts.

IREF

One of the output reference mode enable pin. For internal

reference mode this pin is left open. For the other two modes this

pin should be tied to VPOS.

RFIN

This is the signal input pin. It must be driven from an AC couples

source. The low frequency real input impedance is 200 ohms.

PWDN

This is the power-down mode pin. For the device to operate as a

detector it needs a logical low input (less than 100mV). When a

logic high (greater than VPOS-0.5volts) is applied the device is

turned off and the supply current goes to nearly zero (ground and

internal reference mode less than 5uA, supply reference mode

Vpos divided by 100K).

COMM

This is the device ground pin.

FLTR

By placing a capacitor between this pin and VPOS, the corner

frequency on the modulation filter is lowered. The on-chip filter

is formed with 30pF//500 Ohms.

VRMS

This is the output. It is a near-rail-to-rail voltage output with

limited current drive capabilities. Expected load 10Kohms or

greater.

SREF

The other output reference mode control pin. For supply

reference mode this pin must be connected to VPOS. For the

other to mode it must be connected to COMM (ground).

This information applies to a product under development. Its characteristics and specifications are subject to change without notice. Analog Devices assumes no obligation

regarding future manufacturing unless otherwise agreed to in writing. Patents pending. Rev PrA 8/18/99

Analog Devices Confidential Information