ANALOG DEVICES AD8311 Service Manual

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FEATURES

Complete RF detector/controller function >50 dB range at 0.9 GHz (−48 dBm to +3 dBm re 50 Ω) Accurate scaling from 0.1 GHz to 2.5 GHz Temperature-stable linear-in-dB response Log slope of 23 mV/dB, intercept at −60 dBm at 0.9 GHz True integration function in control loop Low power: 20 mW at 2.7 V

APPLICATIONS

Single, dual, and triple band mobile handset (GSM, DCS,

EDGE)

Transmitter power control

GENERAL DESCRIPTION

The AD8311 is a complete low cost subsystem for the precise control of RF power amplifiers operating in the frequency range

0.1 GHz to 2.5 GHz and over a typical dynamic range of 50 dB. It is intended for use in cellular handsets and other batteryoperated wireless devices. The log amp technique provides a much wider measurement range and better accuracy than controllers using diode detectors. In particular, its temperature stability is excellent over a specified range of −40°C to +85°C.

50 dB GSM PA Controller

AD8311

Its high sensitivity allows control at low signal levels, thus reducing the amount of power that needs to be coupled to the detector. For convenience, the signal is internally ac-coupled. This high-pass coupling, with a corner at approximately

0.016 GHz, determines the lowest operating frequency. Thus, the source can be dc-grounded.

The AD8311 provides a voltage output, VAPC, which has the voltage range and current drive to directly connect to the gain control pin of most handset power amplifiers. VAPC can swing from 300 mV above ground to within 200 mV below the supply voltage. Load currents of up to 6 mA can be supported.

The setpoint control input is applied to pin VSET and has an operating range of 0.25 V to 1.4 V. The associated circuit determines the slope and intercept of the linear-in-dB measurement system; these are nominally 23.6 mV/dB and

−59.7 dBm at 0.9 GHz. Further simplifying the application of the AD8311, the input resistance of the setpoint interface is over 35 MΩ, and the bias current is typically 0.26 µA.

The AD8311 is available in a 6-ball wafer-level chip scale package (WLCSP), 1.0 mm × 1.5 mm, and consumes 7.6 mA from a 2.7 V to 5.5 V supply.

FUNCTIONAL BLOCK DIAGRAM

VPOS

RFIN

10dB

OFFSET

COMPENSATION

COMM

Rev. 0

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.

LOW NOISE

GAIN BIAS

DETDETDETDET

10dB10dB

LOW NOISE BAND GAP

REFERENCE

10dB

INTERCEPT

POSITIONING

Figure 1.

V I

VAPC

FLTR

VSET 23mV/dB

250mV TO

1.4V = 50dB

05545-001

⋅ 1.35

DET

HI-Z

LOW NOISE RAIL-TO- RAI L BUF F E R

www.analog.com

AD8311

TABLE OF CONTENTS

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

Mobile Handset Power Control Example ............................... 15

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

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

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

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

Theory of Operation ...................................................................... 11

Basic Theory................................................................................ 11

Controller-Mode Log Amps ..................................................... 12

Control Loop Dynamics............................................................ 12

Basic Connections...................................................................... 14

Range on VSET and RFIN.........................................................14

Transie n t R espo n s e..................................................................... 15

REVISION HISTORY

6/05—Revision 0: Initial Version

Power-On and Power-Off ......................................................... 16

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

Temperature Drift ...................................................................... 17

Device Calibration and Error Calculation.............................. 17

Selecting Calibration Points to Improve Accuracy over a Reduced Range

Device Handling......................................................................... 19

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

Outline Dimensions ....................................................................... 22

Ordering Guide .......................................................................... 22

........................................................................... 18

Rev. 0 | Page 2 of 24

AD8311

SPECIFICATIONS

VPOS = 2.7 V, Frequency = 0.1 GHz, TA = 25°C, 52.3 Ω termination on RFIN, light condition = 600 lux, unless otherwise noted.

Table 1.

Parameter Conditions Min Typ Max Unit

SPECIFIED FREQUENCY RANGE RFIN (Pin 6) 0.1 2.5 GHz MEASUREMENT MODE1 (f = 0.1 GHz)

Input Impedance No termination resistor on RFIN 2140 || 1.97 Ω || pF ±1 dB Dynamic Range TA = +25°C

Maximum Input Level Minimum Input Level

2

Slope

−40°C < T

±1 dB error ±1 dB error

21.5 23.8 25.5 mV/dB

< +85°C

A

Intercept2 −66 −58.9 −51 dBm VSET Voltage—High Power In PIN = –10 dBm 1.16 V VSET Voltage—Low Power In PIN = –40 dBm 0.45 V Temperature Sensitivity PIN = –10 dBm

25°C ≤ T

−40°C ≤ T

≤ +85°C

A

≤ +25°C

A

MEASUREMENT MODE (f = 0.9 GHz)

Input Impedance No termination resistor on RFIN 370 || 1.58 Ω || pF ±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

Slope2 23.6 mV/dB Intercept2 −59.7 dBm VSET Voltage—High Power In PIN = –10 dBm 1.17 V VSET Voltage—Low Power In PIN = –40 dBm 0.46 V Temperature Sensitivity PIN = –10 dBm

25°C ≤ T

−40°C ≤ T

≤ +85°C

A

≤ +25°C

A

MEASUREMENT MODE (f = 1.9 GHz)

Input Impedance No termination resistor on RFIN 180 || 1.67 Ω || pF ±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

Slope2 22.7 mV/dB Intercept2 −60.8 dBm VSET Voltage—High Power In PIN = –10 dBm 1.15 V VSET Voltage—Low Power In PIN = –40 dBm 0.47 V Temperature Sensitivity PIN = –10 dBm

25°C ≤ T

−40°C ≤ T

≤ +85°C

A

≤ +25°C

A

47 dB 46 dB +2 +2.6 dBm

−44.5 −44 dBm

−0.0020 +0.0121

dB/°C dB/°C

51 dB 50 dB +2.8 dBm

−47.9 dBm

0.0015

0.0094

dB/°C dB/°C

42 dB 41 dB

−5.6 dBm

−48.0 dBm

0.0056

0.0077

dB/°C dB/°C

Rev. 0 | Page 3 of 24

AD8311

Parameter Conditions Min Typ Max Unit

MEASUREMENT MODE (f = 2.5 GHz)

Input Impedance No termination resistor on RFIN 164 || 1.55 Ω || pF ±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

Slope2 22.5 mV/dB Intercept2 −60.6 dBm VSET Voltage—High Power In PIN = –10 dBm 1.14 V VSET Voltage—Low Power In PIN = –40 dBm 0.46 V Temperature Sensitivity PIN = –10 dBm

25°C ≤ T

−40°C ≤ T

≤ 85°C

A

≤ +25°C

A

OUTPUT INTERFACE VAPC (Pin 2)

Minimum Output Voltage V Maximum Output Voltage I R vs. Temperature 85°C, V

≤ 150mV 0.2 0.3 0.4 V

SET

= 3 mA 2.3 2.55 V

OUT

= ∞ 2.4 2.65 V

L

POS

= 3 V, I

= 6 mA 2.54 V

OUT

General Limit 2.7 V ≤ VPOS ≤ 5.5 V, RL = ∞ VPOS – 0.1 V Output Current Drive V Output Noise RF Input = 2 GHz, 0 dBm, f

= 1.5 V, RFIN = –50 dBm, source/sink 5/200 mA/µA

SET

= 100 kHz, C

NOISE

= 220 pF 170 nV/√Hz

FLT

Small Signal Bandwidth RFIN = −10 dBm; from FLTR to VAPC 30 MHz Fall Time Input level = off to 0 dBm, 90% to 10% 120 ns Rise Time Input level = 0 dBm to off, 10% to 90% 270 ns Slew Rate 90% – 10%, V

= 0.3 V, open loop 15 V/µs

SET

Response Time FLTR = Open 130 ns

VSET INTERFACE VSET (Pin 3)

Nominal Input Range RFIN = 0 dBm; measurement mode RFIN = −50 dBm; measurement mode Logarithmic Scale Factor 0.04 dB/mV Bias Current Source RFIN = −10 dBm; V

= 1.4 V 0.26

SET

Input Resistance 36 MΩ Slew Rate 14 V/µs

POWER INTERFACE VPOS (Pin 1)

Supply Voltage 2.7 5.5 V Quiescent Current 5 7.6 10.7 mA vs. Temperature

Power-On Time

Power-Off Time

1

VAPC (Pin 2) to VSET (Pin 3) with inversion stage, sinusoidal input signal.

2

Mean and standard deviation specifications are available in . Table 4

–40°C ≤ T Time from VPOS high to V

V

SET

Time from VPOS low to V V

SET

≤ +85°C

A

≤ 200 mV

within 1% of final value,

APC

within 1% of final value,

APC

42 dB 41 dB

−6.2 dBm

−47.7 dBm

−0.0004 +0.0090

dB/°C dB/°C

1.4 V

0.27 V

µA

8.2 12.9 mA 3 10 µs

100 2000 ns

Rev. 0 | Page 4 of 24

AD8311

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameters Ratings

Supply Voltage VPOS 5.5 V VAPC, VSET 0 V, VPOS RFIN 17 dBm Equivalent Voltage 1.6 V rms Internal Power Dissipation 60 mW θJA (WLCSP) 200°C/W Maximum Junction Temperature 125°C Operating Temperature Range −40°C to +85°C Storage Temperature Range −65°C to +150°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. 0 | Page 5 of 24

AD8311

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

BUMP 1 INDICATOR

VPOS RFIN

VAPC

VSET FLTR

6

1

5

2

4

3

TOP VIEW

Not to Scale

COMM

05545-002

Figure 2. Pin Configuration

Table 3. Pin Function Descriptions

Pin No. Mnemonic Function

1 VPOS Positive Supply Voltage: 2.7 V to 5.5 V. 2 VAPC Output. Control voltage for gain control element. 3 VSET Setpoint Input. Nominal input range 0.25 V to 1.4 V. 4 FLTR Integrator Capacitor. Connect between FLTR and COMM. 5 COMM Device Common (Ground). 6 RFIN RF Input.

Rev. 0 | Page 6 of 24

AD8311

TYPICAL PERFORMANCE CHARACTERISTICS

VPOS = 2.7 V; TA = 25°C; C

−40°C = blue, +85°C = red.

10

0

–10

–20

–30

–40

RF INPUT AMPLITUDE (dBm)

–50

= open; light condition = 600 lux, 52.3 Ω termination; unless otherwise noted. Colors: +25°C = black,

FLT

0.9GHz

1.9GHz

2.5GHz

0.1GHz

4

3

2

1

0

ERROR (dB)

–1

–2

0.1GHz

1.9GHz

2.5GHz

0.9GHz

–60

0.2 1.6

0.4 0.6 0.8 1.0 1.2 1.4

Figure 3. Input Amplitude vs. V

V

(V)

SET

10

0

–10

–20

–30

–40

RF INPUT AMPLITUDE (dBm)

–50

–60

ERROR AT +85°C AND –40°C BASED ON DEVIATION FROM SLOPE AND INTERCEPT AT +25°C

0.2 1.6

0.4 0.6 0.8 1.0 1.2 1.4 V

(V)

SET

+85°C

+25°C

–40°C

+25°C

Figure 4. Input Amplitude and Log Conformance vs. V

−40°C, +25°C, and +85°C

10

0

–10

–20

+25°C

–40°C

+85°C

at 0.1 GHz

SET

+85°C

4

3

2

1

0

–1

–2

–3

4

3

2

1

05545-017

ERROR (dB)

05545-018

–3

0.2 1.6

0.4 0.6 0.8 1.0 1.2 1.4

Figure 6. Log Conformance vs. V

V

(V)

SET

10

+25°C

0

–10

–20

–30

–40

RF INPUT AMPLITUDE (dBm)

–50

ERROR AT +85°C AND –40°C BASED ON DEVIATION FROM SLOPE AND INTERCEPT AT +25°C

–60

0.2 1.6

0.4 0.6 0.8 1.0 1.2 1.4 V

SET

–40°C

+85°C

–40°C

+25°C

(V)

Figure 7. Input Amplitude and Log Conformance vs. V

−40°C, +25°C, and +85°C

10

0

–10

–20

+25°C

–40°C

SET

+85°C

4

3

+85°C

2

1

0

–1

–2

–3

at 1.9 GHz

4

3

2

1

05545-020

ERROR (dB)

05545-021

–30

–40

RF INPUT AMPLITUDE (dBm)

–50

–60

ERROR AT +85°C AND –40°C BASED ON DEVIATION FROM SLOPE AND INTERCEPT AT +25°C

0.2 1.6

0.4 0.6 0.8 1.0 1.2 1.4 V

SET

(V)

–40°C

+25°C

Figure 5. Input Amplitude and Log Conformance vs. V

−40°C, +25°C, and +85°C

at 0.9 GHz

SET

0

ERROR (dB)

–1

–2

–3

05545-019

Rev. 0 | Page 7 of 24

–30

–40

RF INPUT AMPLITUDE (dBm)

–50

ERROR AT +85°C AND –40°C BASED ON DEVIATION FROM SLOPE AND INTERCEPT AT +25°C

–60

0.2 1.6

0.4 0.6 0.8 1.0 1.2 1.4

+25°C

V

SET

–40°C

(V)

Figure 8. Input Amplitude and Log Conformance vs. V

−40°C, +25°C, and +85°C

+85°C

at 2.5 GHz

SET

0

–1

–2

–3

ERROR (dB)

05545-022

AD8311

3

2

1

0

ERROR (dB)

–1

–2

–3

–60

–50 –40 –30 –20 –10 0

RF INPUT AMPLITUDE (dBm)

+25°C

–40°C

+85°C

10

05545-023

Figure 9. Distribution of Error over Temperature After Ambient Normalization

vs. Input Amplitude at 0.1 GHz

3

2

+25°C

–40°C

+85°C

10

05545-024

1

0

ERROR (dB)

–1

–2

–3

–60

–50 –40 –30 –20 –10 0

RF INPUT AMPLITUDE (dBm)

Figure 10. Distribution of Error over Temperature after Ambient Normalization

vs. Input Amplitude at 0.9 GHz

3.5

2

1

0

ERROR (dB)

–1

–2

–3

–60

–40°C

–50–40–30–20–10 0

RF INPUT AMPLITUDE (dBm)

+25°C

+85°C

10

05545-026

Figure 12. Distribution of Error over Temperature After Ambient Normalization

vs. Input Amplitude at 1.9 GHz

3

2

+85°C

1

0

ERROR (dB)

–1

+25°C

–2

–3

–50–40–30–20–10 0

–60

RF INPUT AMPLITUDE (dBm)

–40°C

10

05545-027

Figure 13. Distribution of Error over Temperature after Ambient Normalization

vs. Input Amplitude at 2.5 GHz

3.3

3.1

(V)

2.9

APC

V

2.7

2.5

2.3

2.7 3.5

0mA

2mA

2.8 2.9 3.0 3.1 3.2 3.3 3.4 V

POS

4mA

6mA

(V)

Figure 11. Maximum V

Voltage vs. Supply Voltage by Load Current

APC

05545-025

Rev. 0 | Page 8 of 24

100MHz

900MHz

1.9GHz

2.5GHz

START FREQUENCY = 0.05GHz STOP FREQUENCY = 3.5GHz

05545-028

Figure 14. Input Impedance vs. Frequency, No Termination Resistor on RFIN