Micro Linear Corporation ML2731ET, ML2731CT Datasheet

PRELIMINARY

ML2731 PA Bias Controller

GENERAL DESCRIPTION

The ML2731 is a power amplifier (PA) bias controller with
support circuits for a typical radio transceiver. The IC
integrates a PA bias controller, a PA DC switch, a crystal
oscillator circuit, a negative voltage generator and two
voltage regulators. It can be used with GaAs FETs and
silicon bipolar devices.

Micro Linear’s ML2731, along with the ML2712 and the
ML2713, form a complete transceiver solution for the 2.4
GHz IEEE802.11 communication standard, as well as
other wireless ISM communication products.

In addition to supporting Micro Linear’s transceiver chip
set, the ML2731 can stand alone as:

A compact bias voltage controller
A compact negative voltage generator
A compact crystal oscillator

FEATURES

n

Sets PA current and power output using a bias control
loop

n

Integrates a PA DC supply switch

n

Prevents PA power-on if negative voltage is not present

n

Integrates all circuits needed for supporting a crystal
oscillator with 10MHz to 40MHz frequency range

n

Incorporates a fast starting, high switching frequency,
negative voltage generator requiring only small
ceramic capacitors

n

Contains voltage regulators for an oscillator, a negative
voltage generator and a 50mA 3.0V LDO output

n

Requires less than 1mA of current when powered down

n

Supply voltage ranges from 3.3V to 5.5V

APPLICATIONS

n

Cellular and Cordless Radios

n

WLAN Radios

n

Radios with GaAs FET Power Amplifiers

n

Fixed and Mobile radio transceivers

SIMPLIFIED BLOCK DIAGRAM

VPA

VBIAS

VNEG

GaAs FET Power Amplifier

PRELIMINARY DATASHEET

C1
C2

PA on/off switch

and current sense

Bias Control

Negative voltage

generator

Voltage

Regulator

REGO

ML2731

Crystal

Oscillator

Sine & square

wave drivers

CLKO

SINO

ML2712
ML2713

Radio

January, 2000

PAEN

ICON

NEGEN

XIN

Crystal

XOUT

PDN

Baseband Controller

(e.g. MSM7730B)

PRELIMINARY

ML2731

TABLE OF CONTENTS

General Description ................................................................................................................................................... 1

Simplified Block Diagram .......................................................................................................................................... 1

Features...................................................................................................................................................................... 1

Applications ............................................................................................................................................................... 1

Block Diagram ........................................................................................................................................................... 3

Pin Configuration ....................................................................................................................................................... 4

Pin Descriptions ......................................................................................................................................................... 4

Functional Description ............................................................................................................................................... 6

Introduction.............................................................................................................................................................. 6

External Interfaces ................................................................................................................................................... 6

Mode Control ........................................................................................................................................................... 6

Description Of Operation ........................................................................................................................................... 6

Crystal Oscillator ..................................................................................................................................................... 7

Negative Voltage Generator ..................................................................................................................................... 7

Absolute Maximum Ratings........................................................................................................................................ 11

Electrical Tables ......................................................................................................................................................... 11

Electrical Characteristics............................................................................................................................................ 11

Operating Conditions ................................................................................................................................................. 11

Physical Dimensions .................................................................................................................................................. 12

Ordering Information .................................................................................................................................................. 12

WARRANTY

Micro Linear makes no representations or warranties with respect to the accuracy, utility, or completeness
of the contents of this publication and reserves the right to make changes to specifications and product
descriptions at any time without notice. No license, express or implied, by estoppel or otherwise, to any
patents or other intellectual property rights is granted by this document. The circuits contained in this
document are offered as possible applications only. Particular uses or applications may invalidate some of
the specifications and/or product descriptions contained herein. The customer is urged to perform its own
engineering review before deciding on a particular application. Micro Linear assumes no liability
whatsoever, and disclaims any express or implied warranty, relating to sale and/or use of Micro Linear
products including liability or warranties relating to merchantability, fitness for a particular purpose, or
infringement of any intellectual property right. Micro Linear products are not designed for use in medical,
life saving, or life sustaining applications.

© 2000. Micro Linear is a registered trademark of Micro Linear Corporation. All other trademarks are the property of their
respective owners.

Products described herein may be covered by one or more of the following U.S. patents: 4,897,611; 4,964,026; 5,027,116;
5,281,862; 5,283,483; 5,418,502; 5,508,570; 5,510,727; 5,523,940; 5,546,017; 5,559,470; 5,565,761; 5,592,128; 5,594,376;
5,652,479; 5,661,427; 5,663,874; 5,672,959; 5,689,167; 5,714,897; 5,717,798; 5,742,151; 5,747,977; 5,754,012; 5,757,174;
5,767,653; 5,777,514; 5,793,168; 5,798,635; 5,804,950; 5,808,455; 5,811,999; 5,818,207; 5,818,669; 5,825,165; 5,825,223;
5,838,723; 5.844,378; 5,844,941. Japan: 2,598,946; 2,619,299; 2,704,176; 2,821,714. Other patents are pending.

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PRELIMINARY DATASHEET

January, 2000

BLOCK DIAGRAM

PRELIMINARY

ML2731

XIN

XOUT

PAEN

NEGEN

PDN

REGO

SINO

15

16

6

7

14

3

CLKO

1 8

BUFFER

AND

DRIVERS

OSCILLATOR

AND

DIVIDER

REFERENCE

GENERATOR

AND

LOGIC

REGULATOR

NEGATIVE

VOLTAGE

GENERATOR

BIAS

CONTROL

SWITCH

AND

CURRENT

SENSE

VCC

2

10

VNEG

12

C1

11

C2

5

ICON

4

VBIAS

13

VPA

January, 2000

9

GND

PRELIMINARY DATASHEET

3

PRELIMINARY

PIN CONFIGURATION

ML2731

16-Pin TSSOP (T16)

SINO

VCC

REGO

VBIAS

ICON

PAEN

NEGEN

CLKO

PIN DESCRIPTIONS

Pin # Signal Name I/O Description

1 SINO O (ANLG) Sine wave output. This pin is a low impedance output capable of

2 VCC O (ANLG) DC power supply

1

2

3

4

5

6

7

8

TOP VIEW

16

15

14

13

12

11

10

9

XOUT

XIN

PDN

VPA

C1

C2

VNEG

GND

driving a 2kW load. The signal is sourced with either a crystal
interfaced with on-chip components through XOIN (pin 15) and XOUT
(pin 16) or with a completely external oscillator through pin 15.
Taking PDN (pin 14) high switches off output

ML2731

3 REGO O (ANLG) IC regulator output. This is the output from the on IC regulator. It is

disabled in the SLEEP mode of operation and enabled in all other
modes. The nominal output voltage is 2.9 V and it has a low
impedance output which can source up to 50mA

4 VBIAS O (ANLG) PA bias voltage output. This output has limited drive capability of 3mA

and is intended to drive the gate or bias of the PA

5 ICON I (ANLG) Reference current input. Used by the PA bias control loop to set the PA

current level. This input appears as a virtual ground

6 PAEN I (CMOS) PA Enable. Transitions from high to low on this pin activate the PA

current ramp up function, switch the PA voltage supply switch on and
enable the PA bias control loop. Transitions from low to high activate
the PA current ramp down function and switch the PA voltage supply
off

7 NEGEN I (CMOS) Negative Voltage Enable. In conjunction with PDN and PAEN, NEGEN

controls the operational mode of the IC and enables the negative
voltage generator circuits

8 CLKO I (CMOS) Clock output. The frequency is set with either a crystal interfaced with

on-chip components through XOIN (pin 15) and XOUT (pin 16) or with
a completely external oscillator through pin 15. CLKO switches off
when device goes into SLEEP mode when PDN is taken high

9 GND GND Ground

10 VNEG O (ANLG) Negative regulator output. This pin is one of the outputs of the negative

switching regulator. A capacitor connected serves as a current
reservoir. Typically a 100nF capacitor is connected between pin 10
and GND

11 C2 O (ANLG) Noise Shunt. Negative voltage generator capacitor connection. This

output of the negative switching regulator shunts regulator noise to
ground using a 100nF bypass capacitor

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PRELIMINARY DATASHEET

January, 2000