VMMK-3213-TR1G Avago Technologies US Inc., VMMK-3213-TR1G Datasheet - Page 7

• Manufacturer Part Number: VMMK-3213-TR1G
• Description: RF Amplifier Directional Detector
• Manufacturer: Avago Technologies US Inc.
• Series: -r

Specifications of VMMK-3213-TR1G

• Frequency: 6GHz ~ 18GHz
• Rf Type: General Purpose
• Input Range: -5dBm ~ 30dBm
• Accuracy: -
• Voltage - Supply: -
• Current - Supply: 190µA
• Package / Case: 0402 (1005 Metric)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

VMMK-3213 Biasing Information
Biasing and Operation
The VMMK-3213 is a 3 terminal device consisting of a
“through” 50 ohm line connecting directly between the RF
Input and RF Output ports, and a directional coupler with a
full wave detector that provides a DC output proportional
to RF power input. As with any high frequency device,
good grounding is required on the common port under
the device for it to produce low loss in the “through” mode.
A suggested PCB layout with appropriate grounding will
be cover later in the application section.
With only 3 terminals available, the DC bias and detected
voltage are internally DC coupled to the input and output
terminals respectively. The key to successful operation
of the VMMK-3213 is the use of low loss bias decoupling
networks connected to both the RF Input and the RF
Output ports. Figure 7 shows a simple biasing circuit.
The bias decoupling networks provide a low loss AC
coupled RF path to the device, a means of biasing the
device on the input, and a means of extracting the
detected voltage on the output of the device. Bias decou-
pling networks in the 6 to 18 GHz frequency range can be
easily produced using simple lumped resistors and lumped
capacitors. All SMT components are suggested to be of
0402 or 1005 size. The detector needs two DC blocking
RFin
Figure 7. Biasing the VMMK-3213 Detector Module
7
Component
C1, C2
R1
R2
C3, C4
R3
Vb
C1
C3
R1
Description
0.5 pF to 2 pF
(Vb -1.5) / 0.00014 Ω
10 kΩ
1 pF to 2 pF
External load resistor (optional)
bias
detector
R2
C4
C2
R3
RFout
Vdet
caps, C1 and C2, on the input and output ports. This can be
accomplished by using SMT capacitors with values chosen
for the frequency of operation; e.g. 1 pF is suggested for
10-14 GHz operation. Nominal bias voltage of 1.5 V or 0.14
mA is required for proper operation. Biasing on the input
is by a way of a large value resistor R1. Its value can be
computed using the following equation:
R1 = (Vb -1.5) / 0.00014
where Vb is the supply voltage.
Detected dc voltage is extracted on the output by a way of
a large value resistor R2, in the range of 10 kΩ. Bypassing
capacitors C3 and C4 are needed to prevent RF influence
on the dc lines. Suggested value for bypass capacitors is
1 pF.
At zero RF input power, and at 1.5 V supply bias, a nominal
62 mV offset voltage appears at the detected output port.
The internal output source resistance for the detector is
approximately 20 kΩ. Resistor R3 can be used as an
external load resistor for the detector. Its value can be
optimized for the desired Vout vs. RF input curve.
Figure 8 shows a photo of a VMMK-3213 populated PCB
used to obtain the Vdet vs. Input Power characterization
data from 6 to 18 GHz. For ease in broadband charac-
terization, no on board DC blocking caps were present;
instead, external broadband dc blocking capacitors
(in 3.5 mm connectors) were used.
Figure 8. VMMK-3213 Characterization Board
(Note: Need two external DC blocking caps)