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Preliminary 4
Typical Applications * TDMA/CDMA PCS LNA * TDMA/CDMA/FM Cellular LNA * ISM Band LNA/Driver
RF2472
2.4GHZ LOW NOISE AMPLIFIER WITH ENABLE
* Low Noise Transmit Driver Amplifier * General Purpose Amplification * Commercial and Consumer Systems
Product Description
The RF2472 is a general purpose, low-cost, high-performance amplifier designed for operation from a 2.7V to 4V supply with low current consumption. The device is optimized for 2.4GHz LNA applications, but is also useful for 1.9GHz PCS and K-PCS, 900MHz ISM, and 1.5GHz 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.
1.60 + 0.01 0.400
1
4
GENERAL PURPOSE AMPLIFIERS
0.15 0.05
2.90 + 0.10
0.950
2.80 + 0.20 3 MAX 0 MIN 0.45 + 0.10 0.127
1.44 1.04
Dimensions in mm.
Optimum Technology Matching(R) Applied
Si BJT Si Bi-CMOS
Package Style: SOT 5 Lead
uSiGe HBT
GaAs HBT
GaAs MESFET Si CMOS
Features * DC to >6GHz Operation * 2.7V to 4.0V Single Supply * High Input IP3 * 1.5dB Noise Figure at 2400MHz * 14dB Gain at 2400MHz * Low Current Consumption of 6mA at 3V
VCC 1 GND 2 RF IN 3
5 RF OUT
4 PD
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
RF Micro Devices, Inc. 7628 Thorndike Road Greensboro, NC 27409, USA
Tel (336) 664 1233 Fax (336) 664 0454 http://www.rfmd.com
Rev A6 011023
4-87
RF2472
Absolute Maximum Ratings Parameter
Supply Voltage Input RF Level Operating Ambient Temperature Storage Temperature
Preliminary
Rating
-0.5 to 4.0 0 -40 to +85 -40 to +150
Unit
V dBm C C Caution! ESD sensitive device.
RF Micro Devices believes the furnished information is correct and accurate at the time of this printing. However, RF Micro Devices reserves the right to make changes to its products without notice. RF Micro Devices does not assume responsibility for the use of the described product(s).
Parameter
Overall
Specification Min. Typ. Max.
DC to >6000 13.0 +8.0 14.6 1.5 +10.0 -10 17.0 +20.0
Unit
MHz
Condition
T=27C, VCC =3.0V T=27C, VCC =3.0V, Freq=2440MHz
4
GENERAL PURPOSE AMPLIFIERS
Frequency Range
2.4GHz LNA Operation
Gain Noise Figure Input IP3 Input P1dB dB dB dBm dBm
Two tones at 1MHz spacing, -15dBm output T=27C, VCC =3.0V, Freq=1960MHz
PCS and K-PCS LNA Operation
Gain Noise Figure Input IP3 Input P1dB 16.3 1.4 +8 -12 2.7 to 3.6 6.0 <1.0 dB dB dBm dBm V mA A
Two tones at 1MHz spacing, -12dBm output
Power Supply
Operating Voltage Operating Current 4.0 8.0 3.0 VCC =3.0V, PD =3.0V VCC =3.0V, PD =0V
4-88
Rev A6 011023
Preliminary
Pin 1 2 3 Function VCC GND RF IN Description
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 50 at 2.4GHz.
RF2472
Interface Schematic
See pin 3.
VCC PD BIAS RF OUT RF IN
4
PD
5
RF OUT
Power down pin.This pin enables the bias to the amplifier. To turn the amplifier on, this pin should be connected to VCC. Connecting this pin to ground, will turn the amplifier off and reduce the current draw to below 1A. 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 VCC through a choke or matching inductor. This pin is typically matched to 50 with a shunt bias/matching inductor and series blocking/matching capacitor. Refer to application schematics.
4
GENERAL PURPOSE AMPLIFIERS
See pin 3.
Rev A6 011023
4-89
RF2472
Theory of Operation
The RF2472 is a low-noise amplifier with internal 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 practical, ground should be provided by a via hole directly to a continuous ground layer. Highly reflective terminations to the RF input and output pins should be avoided whenever possible. In most circumstances, a resistor in parallel with an inductor in the bias line on pin 5 will improve the stability of the circuit. See the application schematics for examples. The 10nH inductor in the bias line is part of an output impedance matching circuit. At higher frequencies, the impedance of the matching circuit, alone, would become highly inductive. 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.
Preliminary
4
GENERAL PURPOSE AMPLIFIERS
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. 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 model is not a good fit.
4-90
Rev A6 011023
Preliminary
Application Schematic - 1.9GHz
VCC
RF2472
22 pF
VCC 1.8 k 22 nF 1 2 2.7 nH RF IN 0.5 pF 22 nF 3 4 22 nF PD 5 10 nH 22 nF RF OUT 5.6 nH
4
GENERAL PURPOSE AMPLIFIERS
Application Schematic - 2.4GHz
VCC
22 pF
VCC 1.0 k 22 nF 1 2 22 nF RF IN 3 4 22 nF PD 5 10 nH 22 nF RF OUT 5.6 nH
Rev A6 011023
4-91
RF2472
Evaluation Board Schematic - 1.9GHz
(Download Bill of Materials from www.rfmd.com.)
P1 P1-1 1 2 PD GND P2-1 P2 1 2 VCC GND C6 3 pF C2 15 nF VCC 1 L3 2.7 nH C3 0.5 pF C1 10 nF 2 50 strip 3 4 C8 15 nF R4 1.8 k 5 L2 5.6 nH R1 1 k L1 10 nH R3 10 C7 15 nF
Preliminary
VCC
U1
50 strip C4 15 nF
50 strip
J2 RF OUT
4
GENERAL PURPOSE AMPLIFIERS
J1 RF IN
50 strip
PD
Evaluation Board Schematic - 2.4GHz
P1 P1-1 1 2 PD GND P2-1 P2 1 2 VCC1 GND C6 3 pF C2 15 nF VCC C1 15 nF 1 2 3 4 C8 15 nF R4 1.0 k 5 L2 5.6 nH R1 1 k PD C4 15 nF L1 10 nH R3 10 C7 15 nF VCC
U1
50 strip
J2 RF OUT
J1 RF IN
50 strip
2472400-
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
RF2472
4
GENERAL PURPOSE AMPLIFIERS
Evaluation Board Layout - 2.4GHz Board Size 1.0" x 1.0"
Board Thickness 0.031"; Board Material FR-4
Rev A6 011023
4-93
RF2472
Gain versus Frequency
25.0
Preliminary
20.0
15.0
S21 (dB)
10.0
4
GENERAL PURPOSE AMPLIFIERS
5.0
0.0 0.0 1.0 2.0 3.0 4.0 5.0
Frequency (GHz)
Smith Chart
1.0
6 0.
Swp Max 5.00069GHz
2. 0
0.8
S1,1
-10.0
S2,2
.4 -0
-0 .6
-0.8
.0 -2
Swp Min 0.1GHz
4-94
-1.0
-4 .0 -5. 0
2 -0.
10.0
-3 .0
0.2
0.4
0.6
0.8
1.0
2.0
3.0
4.0
5.0
0
0. 4
0 3.
0 4.
5.0
0.2
10.0
Rev A6 011023

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