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VG025
High Linearity Variable Gain Amplifier
The Communications Edge TM
Product Information
Product Features
• Tunable within 50 – 2200 MHz
• 21 dB Attenuation Range
• Constant +40 dBm OIP3 and +21
dBm P1dB over all gain settings
• Single +5V Supply Voltage
• 16-pin 4x4mm lead-free/green/
RoHS-compliant QFN Package
• MTTF > 1000 years
Applications
• AGC circuitry
• Temperature compensation circuits
• DCS/PCS, cdma2000TM,W-CDMA
Product Description
The VG025 is a high dynamic range variable gain
amplifier (VGA) capable of achieving an analog
attenuation range of up to 21 dB. The +21 dBm output
compression point and +40 dBm output intercept point
of the amplifier are maintained over the entire
attenuation range, making the VG025 ideal for use in
temperature compensation circuits or AGC loops.
The VG025 is available in a lead-free/green/RoHS-
compliant 16-pin 4x4mm QFN surface-mount package
with an exposed backside paddle to allow an MTTF
rating of over 1000 years at a mounting temperature of
+85º C. All devices are 100% RF & DC tested and
packaged on tape and reel for automated surface-mount
assembly.
Functional Diagram
16 15 14 13
N/C 1
12 RF OUT
N/C 2
11 N/C
N/C 3
10
Interstage
Match
RF IN 4
9 N/C
5678
Function
RF Input
Gain Control
Interstage Match
RF Output / DC bias
No Connect or GND
Ground
Pin Number
4
8
6, 10
12
All other pins
Backside slug
Specifications (1)
Typical Performance (1)
Parameter
Units
Operational Bandwidth
MHz
Test Frequency
Gain (2)
Input Return Loss (2)
Output Return Loss (2)
MHz
dB
dB
dB
Output P1dB
Output IP3 (3)
Noise Figure (2)
dBm
dBm
dB
Gain Variation Range (4)
dB
Gain Variation Control Voltage (5) V
Supply Voltage
V
Operating Current Range
mA
Gain Control Pin Current
mA
Min
50
13.5
37
16
0
120
Typ
800
15
6.3
7.6
21.3
39
5.3
21
5
150
26
Max
2200
24
4.5
180
28
1. Test conditions unless otherwise noted: 25ºC, Vsupply = +5 V, in tuned application circuit. Vctrl
is the control voltage through the 120 Ω dropping resistor as shown in the application circuit on page 2.
2. Specifications refer to the device at the maximum gain setting (Vctrl=0V). The input and output
return loss will be dramatically improved with an attenuation setting greater than 1 dB.
3. 3OIP measured with two tones at an output power of +5 dBm/tone separated by 10 MHz. The
suppression on the largest IM3 product is used to calculate the 3OIP using a 2:1 rule.
4. The gain variation range is measured as the difference in gain with Vctrl = 0 and 4.5V at 800 MHz.
5. This voltage refers to the VCTRL as shown in the circuit schematic on page 2. There should be a
series resistance of 120Ω between the control voltage and pin 8 for proper operation.
Parameter
Frequency
Gain (2)
Input Return Loss (2)
Output Return Loss (2)
Output P1dB
Output IP3 (3)
Noise Figure (2)
Gain Variation Range
Units
MHz
dB
dB
dB
dBm
dBm
dB
dB
240
15.4
11
11
21.8
42
4.5
20
Typical
800 1960
15 8.4
6.3 12
7.6 6.5
21.3 22
39 40
5.3 8.1
21 14
2140
8.4
11
5.6
22
40
8.2
13
Absolute Maximum Rating
Parameter
Operating Case Temperature
Storage Temperature
Amplifier Supply Voltage (pin 12)
Pin 8 (Gain Control) Current
RF Input Power (continuous)
Junction Temperature
Rating
-40 to +85 °C
-55 to +125 °C
+6 V
30 mA
4 dB above Input P1dB
+220 °C
Ordering Information
Part No. Description
VG025-G
High Linearity Variable Gain Amplifier
(lead-free/green/RoHS-compliant 4x4mm QFN package)
VG025-PCB240 240 MHz Evaluation Board
VG025-PCB800 800 MHz Evaluation Board
VG025-PCB2000 1.7 – 2.2 GHz Evaluation Board
Operation of this device above any of these parameters may cause permanent damage.
Specifications and information are subject to change without notice
WJ Communications, Inc • Phone 1-800-WJ1-4401 • FAX: 408-577-6621 • e-mail: [email protected] • Web site: www.wj.com
Page 1 of 7 January 2006
VG025
High Linearity Variable Gain Amplifier
The Communications Edge TM
Product Information
Application Circuit Configurations
Circuit Board Material: .014” FR-4, 4 layers, .062” total thickness
The WJ VG025 variable gain amplifier can operate over a very
broad range of frequencies (50 - 2200MHz), but needs specific
matching circuits for specific bands of interest. At the maximum
gain state, reasonable matching is only available for about ±10% of
the reference frequency. The amplifier operates with a typical
current of 150 mA at +5 V while the attenuator current can be varied
from 0 to 30 mA, while maintaining constant OIP3 and P1dB. The
RF matching of the VG025 for the entire frequency range can be
accomplished with the systematic adjustment of only a few parts.
The RF matching is not influenced by different attenuator drive
methods provided there is adequate decoupling of the attenuator bias.
This reference application circuit uses voltage applied between 0
and 4.5V onto the Vctrl as shown on the schematic above. The R2 is
a current limiting resistor to help linearize the drive of the attenuator
and give better attenuator current control.
To properly design the VG025 for an application, pick the frequency
of interest. Choose blocking capacitor values which give RF
impedance of less than 3 ohms. Choose the RF chokes for the
largest inductance while still having resonant frequency about 30%
greater than the Reference frequency (this allows for good isolation
and inductor variation). Next choose L3 and C9 for interstage
matching. C9 is only needed for lower frequencies and determines
the low frequency roll off of the gain. L3 will have dominant
control over the input and output return losses at maximum gain
state (0 mA gain control pin current). C2 is needed to resonate the
package parasitics to achieve the maximum attenuation values with
attenuator current. With attenuator control pin current of 26 mA, C2
can be chosen to provide maximum attenuation. See the chart below
for suggested component values and predicted performance at
various reference frequencies. Component values can be
interpolated for reference frequencies not listed.
For lower frequencies the lumped element values can be used and
the layout with unplaced component pads does not greatly affect the
RF performance of the circuit. For frequencies greater than 500
MHz, component size and trace length have more influence on
circuit performance. Smaller components and shorter trace lengths
reduce the affects of the external component parasitics and
interaction with the multichip module parasitics.
Reference Frequency
C1, C5
C2
C3, C4
C6
C9
L1, L2
L3
L4
R1
R2
Attenuation Range
Maximum Gain
Input Return Loss
Output Return Loss
Output P1dB
Output IP3
Noise Figure
MHz 240
800 1850 1960 2140
pF 1000 56 56 56 56
pF 0 Ω 27 3.6 3.6 3.6
μF .01 .01 .01 .01 .01
pF DNP DNP DNP DNP DNP
pF 1.2 DNP DNP DNP DNP
nH 220
22
12
12
12
nH 47 8.2 DNP DNP DNP
nH DNP
82
33
33
33
Ω DNP DNP DNP DNP DNP
Ω 120 120 120 120 120
dB 20 21 12 14 13
dB 15.4
15
8.6
8.4
8.4
dB 11 6.3 11 12 11
dB 11 7.6 7.7 6.5 5.6
dBm 21.8
21.3
22
22
22
dBm 42 39 40 40 40
dB 4.5 5.3 7.9 8.1 8.2
DNP = Do Not Place (Component is not used in the design)
Specifications and information are subject to change without notice
WJ Communications, Inc • Phone 1-800-WJ1-4401 • FAX: 408-577-6621 • e-mail: [email protected] • Web site: www.wj.com
Page 2 of 7 January 2006
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