VMMK-3503-BLKG Avago Technologies US Inc., VMMK-3503-BLKG Datasheet - Page 10

• Manufacturer Part Number: VMMK-3503-BLKG
• Description: RF Amplifier Variable Gain Amp
• Manufacturer: Avago Technologies US Inc.
• Series: -r

Specifications of VMMK-3503-BLKG

• Current - Supply: 58mA
• Frequency: 500MHz ~ 18GHz
• Gain: 12dB
• Noise Figure: 3.5dB
• P1db: 8dBm
• Package / Case: 0402 (1005 Metric)
• Rf Type: 802.16 WiMAX
• Test Frequency: 6GHz
• Voltage - Supply: 3 V ~ 5 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

VMMK-3503 Applications and Usage Information
Figure 23. Evaluation/Test Board (available to qualified customers upon
request)
Biasing and Operation
The VMMK-3503 is biased with a positive supply connected
to the output pin Vd through an external user supplied
bias decoupling network. Nominal current draw is 59
mA from a 5 V power supply. A typical biasing scheme is
shown in Figure 23. Maximum gain occurs when Vc is 1.8 V
and minimum gain occurs with Vc set to 0.65 V.
Figure 24. Example demonstration circuit of VMMK-3503 for broadband
operation (RF choke value selected for best performance at 12 GHz).
Figure 25. Biasing the VMMK-3503
10
Input
0.1 F
10 K
100 pF
50 Ohm line
Vc
Input
Pad
Amp
Ground
Pad
Output
Pad
50 Ohm line
0.1 F
100 pF
Vdd
L1
100 pF
Output
Table 4. VMMK-3503 Demo Board BOM
A layout of a typical demo board is shown in Figure 25. The
demo board uses small 0402 style surface mount compo-
nents. Due to the broad bandwidth of the VMMK-3503
devising a bias decoupling network to work well over the
entire 0.5 to 18 GHz frequency range will be a challenge.
Conical wound broad band inductors will work well
but may be pricy. The demo board uses a 2.2 nH output
inductor which provides good bandwidth from about a
1 GHz to beyond 6 GHz. The input and output blocking
capacitors are 100 pF.
Typically a passive component company like Murata does
not specify S parameters at frequencies higher than 5 or
6 GHz for larger values of inductance making it difficult
to properly simulate amplifier performance at higher fre-
quencies. It has been observed that the Murata LQW15AN
series of 0402 inductors actually works quite well above
their normally specified frequency.
Another scheme for increasing the bandwidth would be
to install two small chip inductors in series. A smaller value
would favor the higher frequencies while the larger value
will work better at low frequencies. Putting a few ohms
of resistance in series with the inductors will also tend to
smooth out the response by minimizing resonances in the
bias decoupling networks.
The parallel combination of the 100 pF and 0.1 μF capaci-
tors provide a low impedance in the band of operation
and at lower frequencies and should be placed as close
as possible to the inductor. The low frequency bypass
provides good rejection of power supply noise and also
provides a low impedance termination for third order low
frequency mixing products that will be generated when
multiple in-band signals are injected into any amplifier.
The 10K ohm resistor at the input provides a reasonably
wide bandwidth way of injecting Vc at the input to the
device without adversely affecting RF performance.
Component
DUT
C1
C2
R1
C5
C6
L1
Value
VMMK-3503
100 pF
100 pF
10 KOhms
0.1 μF
100 pF
2 nH