View AN1438_599714.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

AN1438 APPLICATION NOTE
LOW NOISE AMPLIFIER OPTIMIZED FOR MINIMUM NOISE FIGURE AT 1.9 GHz USING START420
Data at 1.9GHz (3V, 5mA) Gain = 14dB, IP3out = 10dBm, NF = 1.4dB, RLin = 7dB, RLout = 14dB
1. INTRODUCTION. START420 is a product of the START Family (ST Advanced Radio frequency Transistor). It is a high performance silicon bipolar transistor housed in the ultra miniature 4-lead SC-70 (SOT-343) surface mount plastic package. The amplifier is designed for use with 30mils thickness FR-4 printed circuit board material. The amplifier application circuit has been optimized to achieve a good compromise among Noise Figure, Gain and return loss at 1.9GHz, with Vce=2V and Ic=5mA. The amplifier has 1.4dB of Noise Fifure, 14dB of Gain, an Input Return Loss>7dB, an output Return Loss>14dB and an IP3 of +10dBm (1.9GHz, 3V, 5mA). 2. LNA DESIGN. Figure 1: Schematic Design
J3 2 1
Vcc +3 V +
R3 180 C1 1 F R1 47 C5 100 pF C6 10 nF R2 15
TrL4 100 pF C3 J1 RF_in C2 4 pF L1 8.2 nH TrL5 TrL6 TrL3 TrL1 C4 10 nF Tr1 Start420 TrL2 C7 10 pF
R4 10
J2 RF_out
June 2001
1/4
AN1438 - APPLICATION NOTE This amplifier is realized with a microstrip line as matching elements and a small number of surfacemount components. A single pin (Vcc=3V) for voltage supply is used. A 1F bypass capacitor to filter the supply at the common Vcc node is also used. The transistor's base is connected to the power supply through a choke inductor (microstrip line TrL3) and the transistor's collector is connected to the voltage supply through a choke inductor (microstrip line TrL4). The collector's voltage is 2V. The input matching is realized with a 60 Ohm series transmission line of 15 electrical length (TrL1).The L1 inductor is used to reduce the Noise Figure value The output matching is realized with both a resistor (R4) chip-inductor (L1) and a 60 Ohm series transmission line of 16 electrical length (TrL2). Resistor (R2) is used to improve RF circuit stability. Figure 2: Demoboard Layout
21mm
40mm
Table 1: Bill of Materials Component R1 R2 R3 R4 C1 C2 C3 C4 C5 C6 C7 L1 Tr1 TrL1 TrL2 TrL3 TrL4 TrL5 TrL6 J1 J2 J3
2/4
Value 47 15 180 10 1 4 100 10 100 10 10 8.2
Unit F pF pF nF pF nF pF nH
Size 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 SOT-343
AN1438 - APPLICATION NOTE 3. LNA PERFORMANCE.
S21 20 18 16 14 12 10 8 6 4 2 0 1500
S12 0 -5 -10 (dB) -15 -20 -25 -30 1500
(dB)
1600
1700
1800
1900
2000
1600
1700
1800
1900
2000
Frequency(MHz)
Frequency(MHz)
S11 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 1500
S22 0 -5 -10 (dB) -15 -20 -25
(dB)
1600
1700
1800
1900
2000
-30 1500
1600
1700
1800
1900
2000
Frequency(MHz)
Frequency(MHz)
Figure 3: Noise Figure
1.80 1.70 1.60 1.50 NF(dB) 1.40 1.30 1.20 1.10 1.00 1500
1600
1700
1800
1900
2000
Frequency(MHz)
3/4
AN1438 - APPLICATION NOTE
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specification mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a trademark of STMicroelectronics (c) 2001 STMicroelectronics - Printed in Italy - All rights reserved
STMicroelectronics GROUP OF COMPANIES Australia - Brazil - China - Finland - France - Germany - Hong Kong - India - Italy - Japan - Malaysia - Malta - Morocco Singapore - Spain - Sweden - Switzerland - United Kingdom - U.S.A. http://www.st.com
4/4

▲Up To Search▲

Price & Availability of AN1438

	To Download AN1438 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .