Datasheet RF2472, RF2472PCBA-410, RF2472PCBA-411 Datasheet (RF Micro Devices)

Preliminary

RF2472

4

2.4 GHZ LOW NOISE AMPLIFIER WITH ENABLE

Typical Applications

• TDMA/CDMA PCS LNA

• TDMA/CDMA/FM Cellular LNA

• ISM Band LNA/Driver

Product Description

The RF2472 is a general purpose, low-cost, high-perfor­mance amplifier designed for operation from a 2.7 V to 4V
supply with low current consumption. The device is opti­mized for 2.4GHz LNA applications, but is also useful for

1.9 GHz PCS and K-PCS, 900MHz ISM, and 1.5 G Hz
GPS applications. The RF2472 is available in a very
small industry-standard SOT23 5-lead surface mount
package, enabling compact designs which conserve
board space.

• Low Noise Transmit Driver Amplifier

• General Purpose Amplification

• Commercial and Consumer Systems

2.90

+0.10

3° MAX

0° MIN

+0.01

0.950

1.60

1

2.80

+0.20

0.400

0.127

0.15

0.05

1.44

1.04

Dimensions in mm.

4

AMPLIFIERS

GENERAL PURPOSE

Optimum Technology Matching® Applied

Si BJT GaAs MESFETGaAs HBT
Si Bi-CMOS

VCC

GND

RF IN

ü

1

2

3

SiGe HBT

Si CMOS

54RF OUT

PD

0.45

+0.10

Package Style: SOT 5 Lead

Features

• DC to >6GHz Operation

• 2.7V to 4.0V Single Supply

• High Input IP

3

• 1.5dB Noise Figure at 2400MHz

•14dBGainat2400MHz

• Low Current Consumption of 6mA at 3V

Ordering Information

RF2472 2.4GHz Low Noise Amplifier with Enable
RF2472 PCBA-410Fully Assembled Evaluation Board, 2.4GHz
RF2472 PCBA-411Fully Assembled Evaluation Board, 1.9GHz

Functional Block Diagram

Rev A6 011023

RF Micro Devices, Inc.
7628 Thorndike Road
Greensboro,NC 27409, USA

Tel [phone]

Fax [phone]

http://www.rfmd.com

4-87

RF2472

Absolute Maximum Ratings

Parameter Rating Unit

Supply Voltage -0.5 to 4.0 V
Input RF Level 0 dBm
Operating Ambient Temperature -40 to +85 °C
Storage Temperature -40 to +150 °C

Preliminary

Caution! ESD sensitive device.

RF Micro Devices believes the furnishedinformation is correct and accurate
at the time of this printing. However, RF Micro Devices reservesthe right to
make changes to its products without notice. RF Micro Devices does not
assume responsibility for the use of the described product(s).

4

Parameter

Min. Typ. Max.

Overall

Frequency Range DC to >6000 MHz

2.4GHz LNA Operation

Gain 13.0 14.6 17.0 dB
Noise Figure 1.5 dB
Input IP3 +8.0 +10.0 +20.0 dBm Two tones at 1MHz spacing, -15dBm output
Input P

1dB

PCS and K-PCS LNA
Operation

AMPLIFIERS

GENERAL PURPOSE

Gain 16.3 dB
Noise Figure 1.4 dB
Input IP3 +8 dBm Two tones at 1MHz spacing, -12dBm output
Input P

1dB

Specification

-10 dBm

-12 dBm

Unit Condition

T=27°C, VCC=3.0V

T=27°C, VCC=3.0V,Freq=2440MHz

T=27°C, VCC=3.0V,Freq=1960MHz

Power Supply

Operating Voltage 2.7 to 3.6 V
Operating Current 4.0 6.0 8.0 mA V

<1.0 3.0 µAV

=3.0V,PD=3.0V

CC

=3.0V, PD=0V

CC

4-88

Rev A6 011023

Preliminary

RF2472

Pin Function Description Interface Schematic

1VCC
2GND
3RFIN

Supply connection. An external bypass capacitor may be required in
some applications.

Ground connection. Keep traces physically short and connect immedi­ately to ground plane for best performance.

RF input pin. This pin is DC coupled and matched to 50Ω at 2.4GHz.

See pin 3.

VCC

BIASPD

4PD

5RFOUT

Power down pin.This pin enables the bias to the amplifier. To turn the
amplifier on, this pin should be connected to V

to ground, will turn the amplifier off and reduce the current draw to
below 1µA. This pin is a CMOS input. There is no DC current draw
other than the transient current required to charge or discharge the
gate capacitance (less than 5pF).

LNA Output pin.This pin is an open-collector output. It must be biased
to V

matched to 50Ω with a shunt bias/matching inductor and series block­ing/matching capacitor. Refer to application schematics.

. Connecting this pin

CC

through a choke or matching inductor. This pin is typically

CC

RF IN

RF OUT

4

See pin 3.

AMPLIFIERS

GENERAL PURPOSE

Rev A6 011023

4-89

RF2472

Preliminary

Theory of Operation

4

The RF2472 is a low-noise amplifier w ith inter nal bias
circuitry. It is DC-coupled on the input and output;
therefore, it can be used to arbitrarily low frequency. It
has useful gain to above 6GHz. Its design is optimized
for use at 2.4GHz. Because of the high-frequency
gain, the designer must take care to ensure that the
device will remain stable outside the desired operating
frequency. The RF2472 is capable of providing out­standing linearity, but to achieve this high performance,
the circuit designer must pay attention to the termina­tions that are presented to low-frequency intermodula­tion products.

Stability

The RF2472 must be stabilized for frequencies outside
of the desired operating range. Ground connections
should be kept as short as possible. Wherever practi-

AMPLIFIERS

cal, ground should be provided by a via hole directly to

GENERAL PURPOSE

a continuous ground layer. Highly reflective termina­tions to the RF input and output pins s hould be avoided
whenever possible. In most circumstances, a resistor
inparallelwithaninductorinthebiaslineonpin5will
improve the stability of the circuit. See the application
schematics for examples. The 10nH inductor in the
bias line is par t of an output impedance matching cir­cuit. At higher frequencies, the impedance of the
matching circuit, alone, would become highlyinductive.
The large reactive termination of the output port could
cause the circuit to oscillate at a high frequency. The
resistance in parallel with the inductor adds a real part
to the high-frequency termination that will have a stabi­lizing effect on the circuit.

Linearity

The 22nF bypass and coupling capacitors in the appli­cation schematics may seem excessively large for cir­cuits intended to operate at 1.9GHz and 2.4GHz.
These large capacitors provide a low impedance path
to ground for second-order mixing products that leads
to improved third-order intermodulation performance.
The effect is most easily seen for the input coupling
capacitor. A 100pF capacitor would provide low
enough impedance to couple a 2.4GHz signal into the
input pin of the RF2472. However, low-frequency inter­modulation products caused by second-order nonlin­earities would be presented with a large reactive
impedance at the input pin. Relatively large voltages
for these low-frequency products would be allowed to
mix with the fundamental signals at the input pin,
resulting in relatively large, in-band, third-order prod­ucts.

With a large coupling capacitor, the low-frequency
products would be presented with a low impedance,
via the input source impedance, resulting in a lower
voltage at the input pin. These products, in turn, would
mix at a lower level with the fundamental signals to
produce lower in-band, third-order products.

Some designers may be concerned about the self-res­onant frequency of large coupling capacitors. A 22nF
capacitor will probably pass through self resonance
below 100MHz. Beyond resonance, the reactance of
the capacitor will turn inductive, but the internal losses
of the capacitor will usually prevent the component
from exhibiting a large reactive impedance.

4-90

Third-Order Intercept versus 1-dB Compression
Point

For many devices, the third-order intercept point is
approximately 10dB higher than the 1-dB compression
point. This rule of thumb does not apply for the
RF2472. It is normal to find that the third-order inter­cept point is 20 dB higher than the 1-dB compression
point. This behavior is common for SiGe devices. The
reason for the difference is that the 10dB rule is based
on a simple third-order polynomial model for device
nonlinearities. For SiGe devices this simple m odel is
not a good fit.

Rev A6 011023

Preliminary

V

CC

RF IN

2.7 nH

0.5 pF

Application Schematic - 1.9GHz

V

CC

22 pF

1.8 kΩ 10 nH

22 nF

22 nF

1

2

3

5

4

22 nF

5.6 nH

RF2472

22 nF

RF OUT

4

PD

AMPLIFIERS

GENERAL PURPOSE

RF IN

Application Schematic - 2.4GHz

V

CC

22 pF

V

CC

22 nF

22 nF

1

2

3

1.0 kΩ 10 nH

5

4

22 nF

5.6 nH

22 nF

RF OUT

PD

Rev A6 011023

4-91

RF2472

Preliminary

Evaluation Board Schema t ic - 1.9GHz

(Download Bill of Mater ia ls from www.rfmd.com.)

4

P2

1

P2-1 VCC

2

C2

15 nF

50 Ωµstrip

GND

1

2

3

C6

3pF

10 Ω

U1

R4

1.8 kΩ

5

1kΩ

4

C8

15 nF

L1

10 nH

5.6 nH

R1

50 Ωµstrip

L2

C7

R3

15 nF

C4

15 nF

50 Ωµstrip

VCC

J2

RF OUT

PD

AMPLIFIERS

VCC

J1

RF IN

50 Ωµstrip

P1

1

P1-1 PD

2

GND

L3

2.7 nH

C3

0.5 pF

C1

10 nF

Evaluation Board Schema t ic - 2.4GHz

GENERAL PURPOSE

P2-1

C2

15 nF

C1

15 nF

P2

1
2

2472400-

VCC1P1-1 PD
GND

1

2

3

C6

3pF

U1

R4

1.0 kΩ

L1

10 nH

R3

10 Ω

5

L2

5.6 nH

R1

C4

15 nF

1kΩ

4

C7

15 nF

50 Ωµstrip

VCC

J2

RF OUT

PD

C8

15 nF

VCC

J1

RF IN

P1

1

GND

2

50 Ωµstrip

4-92

Rev A6 011023

Preliminary

Evaluation Board Layout - 1.9GHz

Board Size 1.0” x 1.0”

Board Thickness 0.031”; Board Material FR-4

Evaluation Board Layout - 2.4GHz

Board Size 1.0” x 1.0”

Board Thickness 0.031”; Board Material FR-4

RF2472

4

AMPLIFIERS

GENERAL PURPOSE

Rev A6 011023

4-93

RF2472

25.0

20.0

15.0

S21 (dB)

10.0

Preliminary

Gain versus Frequency

4

5.0

0.0

0.0 1.0 2.0 3.0 4.0 5.0

Frequency (GHz)

AMPLIFIERS

GENERAL PURPOSE

4

.

0

2

.

0

0

0.2

S1,1

2

.

0

-

4

.

0

-

6

.

0

0.4

6

.

0

-

Smith Chart

8

1.0-1.0

.
0

1.0

0.6

0.8

S2,2

8
.
0

-

2.0

3.0

0

.

2

0

.

2

5.00069GHz

.

3

5.0

4.0

0

.

-

Swp Max

0

0

.

4

0

.

5

.

0

1

10.0

0

.

0

0

.

5

-

0

.

4

-

3

-

Swp Min

0.1GHz

0

1

-

4-94

Rev A6 011023