at-32032 Avago Technologies, at-32032 Datasheet - Page 11

• Manufacturer Part Number: at-32032
• Description: Low Current, High Performance Npn Silicon Bipolar Transistor
• Manufacturer: Avago Technologies

AT-32032 Application
Information
The AT-32032 is described in a
low noise amplifier for use in the
800 to 900 MHz frequency range.
The amplifier is designed for use
with .032 inch thickness FR-4
printed circuit board material.
900 MHz LNA Design
The amplifier is designed for a
V
and a nominal power supply
voltage of 3 volts. The amplifier
schematic is shown in Figure 16.
Figure 16. Schematic Diagram.
Figure 17. Component Parts List.
INPUT
C1,C3 10 pF chip capacitor
C2
C4,C5 1000 pF chip capacitor
L1
L2
L3
L4
Q1
Silicon Bipolar Transistor
R1
R2
R3
R4
R5
R6
Zo
ce
of 2.7 volts and I
Z
o
C4
C2
C1
Open circuited stub .275
inch long
8 nH chip inductor
(Coilcraft 1008CS-080)
Optional (see R1)
56 nH chip inductor
(Coilcraft 1008CS-560)
15 nH chip inductor
(Coilcraft 1008CS-150)
Agilent AT-32032
10K Ω chip resistor (may
want to substitute a 180 nH
chip inductor and 50 W
resistor for lower noise
figure, better low freq
stability, the readjust R2)
26.1 K Ω chip resistor
(adjust for rated Ic)
3.32 K Ω chip resistor
3.32 K Ω chip resistor
51.1 Ω chip resistor
13 Ω chip resistor (see text)
50 Ω microstripline
L2
R1
L1
R2
Q1
R4
R3
R6
c
L3
R5
of 5 mA.
L4
C5
C3
V
CC
Z
= 3 V
OUTPUT
o
A component list is shown in
Figure 17. The artwork including
component placement is shown
in Figure 18.
Figure 18. 1X Artwork showing
Component Placement.
The input matching network uses
a shunt C series L input imped-
ance matching circuit for low
noise. The shunt C is accom-
plished with an open circuited
stub while a chip inductor is used
for the series element. The output
impedance matching network
consists of a series chip inductor.
Bias insertion is accomplished by
the use of small inductors suit-
ably bypassed. A resistor is
placed in series with the output
bias decoupling inductor to de-Q
the network and improve in-band
and low frequency stability.
Surface mount Coilcraft induc-
tors were chosen for their small
size. Resistor R6 enhances broad
band stability especially in the 9
to 10 GHz frequency range.
Biasing
The bias network is designed for
a nominal power supply voltage
of 3 volts. Resistors R1 and R2 are
used to adjust collector current.
Resistor R4 can be attached to
the junction of R5 and C5 to
improve bias point stability.
Performance
The measured gain of the com-
pleted amplifier is shown in
Figure 19. The gain varies
from 15.5 to 16.5 dB over the 800
to 900 MHz frequency range.
IN
AT-3XX32
AT-4XX32
02/98 AJW
.031 FR-4
OUT
Vcc
Noise figure versus frequency is
shown in Figure 20. Best perfor-
mance occurs at 950 MHz provid-
ing a 1.1 dB noise figure.
Measured input and output return
loss is shown in Figure 21. The
input return loss is 7 dB at
900 MHz and can be improved to
9 dB with a 0.1 dB increase in
noise figure by increasing the
amount of capacitance at C2.
Additional capacitance at C2
increases the input return loss
even further with increased noise
figure. Output return loss is a
nominal 12 to 15 dB.
Figure 19. Gain vs Frequency.
Figure 20. Noise Figure vs Frequency.
1.5
1.4
1.3
1.2
1.1
17
16
15
14
13
12
11
10
1
500
500
11
600
600
FREQUENCY (MHz)
FREQUENCY (MHz)
700
700
800
800
900
900
1000
1000