WIRELESS COMMUNICATIONS DIVISION

For additional information and latest specifications, see our website: www.triquint.com

TQ3631

DATA SHEET

3V PCS Band CDMA
LNA IC

Features

Small size: SOT23-8

Single 3V operation

Low-current operation

Gain Select

High IP3 performance

Few external components

Applications

IS-95 CDMA PCS Mobile Phones

Product Description

The TQ3631 is a 3V, RF LNA IC designed specifically for PCS band CDMA
applications. It's RF performance meets the requirements of products designed to
the IS-95 specifications. The TQ3631 is designed to be used with the TQ5631
(CDMA mixer) which provides a complete CDMA receiver for 1900MHz phones.

The LNA incorporates on-chip switches which determine high, low and bypass mode
select. When used with the TQ5631 (CDMA RFA/mixer), four gain steps are
available for use which provide low current/high IP3 and gain. The RF output port is
internally matched to 50

, greatly simplifying the design and minimizing the number

of external components. The TQ3631 achieves excellent RF performance with low
current consumption, supporting long standby and talk times in portable applications.
Coupled with the very small SOT23-8 package, the part is ideally suited for PCS
band mobile phones.

Electrical Specifications

Parameter

Min

Typ

Max

Units

Frequency

1960

MHz

Gain

13.0

Noise Figure

1.5

Input 3

Order Intercept

10.0

dBm

DC supply Current

11.0

Note 1: Test Conditions: Vdd=2.8V, RF=1960MHz, Tc=25C, CDMA High Gain state.

Control

Logic

LNA

gnd

VDD

GND

OUT

50 ohm

RF Out

Control

Logic

GND

TQ3631

Data Sheet

For additional information and latest specifications, see our website: www.triquint.com

Electrical Characteristics

Parameter

Conditions

Min.

Typ/Nom

Max.

Units

RF Frequency

PCS band

1810

1960

1990

MHz

CDMA Mode-High Gain

Gain

12.0

13.0

Noise Figure

1.5

2.2

Input IP3

7.0

10.0

dBm

Input Return Loss (with external matching)

Output Return Loss

Supply Current

11.0

13.0

CDMA Mode-High Gain-Low Linearity

Gain

10.0

11.5

Noise Figure

1.6

2.8

Input IP3

2.0

5.0

dBm

Input Return Loss (with external matching)

Output Return Loss

Supply Current

4.5

5.5

Bypass Mode

Gain

-2.5

-1.5

Noise Figure

2.0

2.8

Input IP3

30.0

dBm

Input Return Loss (with external matching)

Output Return Loss

Supply Current

1.0

2.0

Supply Voltage

2.7

2.8

3.3

Note 1: Test Conditions: Vdd=2.8V, RF=1960MHz, T

= 25

�

C, unless otherwise specified.

Note 2: Min/Max limits are at +25

�

C case temperature, unless otherwise specified.

Absolute Maximum Ratings

Parameter

Value

Units

DC Power Supply

5.0

Power Dissipation

500

Operating Temperature

-40 to 85

Storage Temperature

-60 to 150

Signal level on inputs/outputs

+20

dBm

Voltage to any non supply pin

+0.3

TQ3631

Data Sheet

For additional information and latest specifications, see our website: www.triquint.com

Typical Performance

Test Conditions, unless Otherwise Specified: Vdd=2.8V, Tc=25C, RF=1960MHz

CDMA High Gain Mode

Gain v Freq v Temp

10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

14.5

15.0

1920

1940

1960

1980

2000

Frequency (MHz)

a
in

)

-30C
+25C
+85C

CDMA High Gain Mode

IIP3 v Freq v Temp

7.0

7.5

8.0

8.5

9.0

9.5

10.0

1920

1940

1960

1980

2000

Frequency (MHz)

IIP

3
(d

)

-30C
+25C
+85C

CDMA High Gain Mode

Noise Figure v Freq v Temp

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

1920

1940

1960

1980

2000

Frequency (MHz)

Noi

se Fi

gur

e (

d
B)

-30C
+25C
+85C

CDMA High Gain Mode

Idd v Vdd v Temp

6.00

7.00

8.00

9.00

10.00

11.00

12.00

13.00

2.5

2.7

2.9

3.1

3.3

Vdd (V)

I
dd (

-30C
+25C
+85C

High Gain/Low Linearity Mode

Gain v Freq v Temp

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

12.5

13.0

1920

1940

1960

1980

2000

Frequency (MHz)

a
in

)

-30C
+25C
+85C

High Gain/Low Linearity Mode

IIP3 v Freq v Temp

3.0

3.2

3.4

3.6

3.8

4.0

4.2

4.4

4.6

4.8

5.0

1920

1940

1960

1980

2000

Frequency (MHz)

IIP

3
(d

)

-30C
+25C
+85C

TQ3631

Data Sheet

For additional information and latest specifications, see our website: www.triquint.com

High Gain/Low Linearity Mode

Noise Figure v Freq v Temp

0.00

0.50

1.00

1.50

2.00

2.50

1920

1940

1960

1980

2000

Frequency (MHz)

Noi

se Fi

gur

e (

d
B)

-30C
+25C
+85C

High Gain/Low Linearity Mode

Idd v Vdd v Temp

2.50

3.00

3.50

4.00

4.50

5.00

5.50

2.5

2.7

2.9

3.1

3.3

Vdd (V)

I
dd (

-30C
+25C
+85C

BYPASS Mode

Gain v Freq v Temp

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

1920

1940

1960

1980

2000

Frequency (MHz)

a
in

)

-30C
+25C
+85C

BYPASS Mode

Noise Figure v Freq v Temp

0.00

0.50

1.00

1.50

2.00

2.50

3.00

1920

1940

1960

1980

2000

Frequency (MHz)

Noi

se Fi

gur

e (

d
B)

-30C
+25C
+85C

BYPASS Mode

IIP3 v Freq v Temp

25.0

26.0

27.0

28.0

29.0

30.0

31.0

32.0

33.0

34.0

35.0

1920

1940

1960

1980

2000

Frequency (MHz)

IIP3

(dBm

)

-30C
+25C
+85C

BYPASS Mode

Idd v Vdd v Temp

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

2.5

2.7

2.9

3.1

3.3

Vdd (V)

I
dd (

-30C
+25C
+85C

TQ3631

Data Sheet

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Application/Test Circuit

LNA

GND

RF in

Vdd

GND

(paddle)

RF
out

GND

Control

Logic

LNA input

LNA output

Vdd

Control Logic

Lbrd

Bill of Material for TQ3631 LNA Application/Test Circuit

Component

Reference Designator

Part Number

Value

Size

Manufacturer

Receiver IC

TQ3631

SOT23-8

TriQuint Semiconductor

Capacitor

2.7pF

0402

Capacitor

1.5pF

0402

Resistor

3.3

0402

Inductor

3.9nH

0402

Panasonic

Inductor

Lbrd

See application note

TQ3631

Data Sheet

For additional information and latest specifications, see our website: www.triquint.com

TQ3631 Product Description

The TQ3631 LNA uses a cascode low noise amplifier along with
signal path switching. A bias control circuit sets the quiescent
current for each mode and ensures peak performance over
process and temperature, see Figure 1. In the application,
CMOS level signals are applied to pins 1 and 5 and are
decoded by an internal logic circuit, this sets the device to the
desired mode. See Table 1 for truth table.

In the high gain mode, switches S1, S2, and S5 are closed, with
switches S3 and S4 open. In the bypass mode, switches S1,
S2, and S5 are open, with switches S3 and S4 closed. Six
internal switches ensures there are no parasitic feedback paths
for the RF signal. In the AMPS mode, control logic switches the
LNA into a low current bias condition.

Only three external components are. The chip uses an external
cap and inductor for the input match to pin 3. The output is
internally matched to 50 ohms at pin 6. A Vdd bypass cap is
required close to pin 8.

External degeneration of the cascode is required between pin 4
and ground. However, a small amount of PC board trace can
be used as the inductor. Alternatively, if an extra component
can be tolerated, a small value chip inductor could be used.
See Figure 2.

Figure 1 TQ3631 Simplified Schematic

Operation

MODE

Typical Gain

High Gain

13(dB)

High Gain

Low linearity

11(dB)

Bypass

-2(dB)

Table 1 LNA States and Control Bits

LNA Input Network Design

Input network design for most LNA's is a straightforward
compromise between noise figure and gain. The TQ3631 is no
exception, even though it has 3 different modes. The device
was designed so that one only needs to optimize the input
match in the high gain mode. As long as the proper grounding
and source inductance are used, the other two modes will
perform well with the same match.

It is probably wise to synthesize the matching network
component values for some intermediate range of Gamma
values, and then by experimentation, find the one which
provides the best compromise between noise figure and gain.
The quality of the chip ground will have some effect on the
match, which is why some experimentation will likely be needed.
The input match will affect the output match to some degree, so
S22 should be monitored.

The values used on our evaluation board may be used as a
starting point.

Noise Parameter Analysis

A noise parameter analysis is shown on the next page for the
high gain mode. A "nominal" device was mounted directly on an
evaluation board with semi-rigid probes attached to the device
input and output pins. A value of Lbrd was chosen so that
13.0dB of gain was attained at conjugate match. The tuner was
removed and noise data was taken.

Control

Logic C2

Lbrd

Control

Logic C3

LNA OUT

VDD

GND

RFIN

GND

OUT

GND

VDD

LNA IN

Bias and Switch Control Logic

TQ3631

Data Sheet

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Gamma Opt analysis for TQ3631 High Gain Mode

Freq.

(MHz)

Opt

Angle

Fmin

(dB)

R noise

1800

0.453

95.8

1.476

14.2

1960

0.459

109.4

1.178

9.58

2040

0.437

116.4

1.287

8.17

Gain Control via Pin 4 Inductance

The source connection of the LNA cascode is brought out
separately through pin 4. That allows the designer to make
some range of gain adjustment. The total amount of inductance
present at the source of the cascode is equal to the bond wire
plus package plus external inductance. One should generally
use an external inductance such that gain in the high gain
CDMA mode = 13.0dB. Although it is possible to increase the
gain of the TQ3631 by using little or no degeneration, input
intercept will be degraded.

Figure 2 shows how a spiral PC board trace can be used as the
external inductance. It is suggested that such a circuit be used
for the initial design prototype. Then the optimum inductance
can be found by simply solder bridging across the inductor. The
final PC board design can then include the proper shorted
version of the inductor.

Figure 2 Showing Lbrd and Grounding on Evaluation Board

Selection of the Vdd Bypass Cap for Optimum

Performance

The Vdd bypass capacitor has the largest effect on the LNA
output match, and is required for proper operation. Because the
input match affects the output match to some degree as well,
the process of picking the bypass cap value involves some
iteration. First, an input match is selected which gives adequate
gain and noise figure. Then the bypass capacitor is varied to
give the best output match. The demo board achieves 11-12dB
of return loss which is adequate for connection directly to the
input of a SAW filter.

Grounding

An optimal ground for the device is important in order to achieve
datasheet specified performance. Symptoms of a poor ground
include reduced gain and the inability to achieve <2:1 VSWR at
the output when the input is matched. It is recommended to use
multiple vias to a mid ground plane layer. The vias at pins 2 and
7 to this layer should be as close to the lead pads as possible
Additionally, the ground return on the Vdd bypass cap should
provide minimal inductance back to chip pins 2 and 7.

TQ3631 S-Parameters

Following are S-Parameter graphs for the high gain and high
mode. Data was taken on a single "nominal" device at 2.8v
Vdd. The reference planes were set at the end of the package
pins.

TQ3631

Data Sheet

Additional Information

For latest specifications, additional product information, worldwide sales and distribution locations, and information about TriQuint:

Web: www.triquint.com

Tel: (503) 615-9000

Email: info_wireless@tqs.com

Fax: (503) 615-8900

For technical questions and additional information on specific applications:

Email: info_wireless@tqs.com

The information provided herein is believed to be reliable; TriQuint assumes no liability for inaccuracies or omissions. TriQuint assumes no responsibility for the use of

this information, and all such information shall be entirely at the user's own risk. Prices and specifications are subject to change without notice. No patent rights or
licenses to any of the circuits described herein are implied or granted to any third party.

For additional information and latest specifications, see our website: www.triquint.com

Package Type: SOT23-8 Plastic Package

DESIGNATION

DESCRIPTION

METRIC

ENGLISH

NOTE

OVERALL HEIGHT

1.20 +/-.25 mm

0.05 +/-.250 in

STANDOFF

.100 +/-.05 mm

.004 +/-.002 in

LEAD WIDTH

.365 mm TYP

.014 in

LEAD THICKNESS

.127 mm TYP

.005 in

PACKAGE LENGTH

2.90 +/-.10 mm

.114 +/-.004 in

1,3

LEAD PITCH

.65 mm TYP

.026 in

LEAD TIP SPAN

2.80 +/-.20 mm

.110 +/-.008 in

PACKAGE WIDTH

1.60 +/-.10 mm

.063 +/-.004 in

2,3

FOOT LENGTH

.45 +/-.10 mm

.018 +/-.004 in

Theta

FOOT ANGLE

1.5 +/-1.5 DEG

Notes

1. The package length dimension includes allowance for mold mismatch and flashing.
2. The package width dimension includes allowance for mold mismatch and flashing.
3. Primary dimensions are in metric millimeters. The English equivalents are calculated and subject to rounding error.

FUSED LEAD

Note 1

PIN 1

Note 2

DIE

Электронный компонент: TQ3631

Document Outline