XP1019-BD_08 Datasheet, PDF (5/8 Pages) Mimix Broadband – 17.0-24.0 GHz GaAs MMIC

17.0-24.0 GHz GaAs MMIC
Power Amplifier
October 2008 - Rev 10-Oct-08
P1019-BD
App Note [1] Biasing - It is recommended to separately bias each amplifier stage Vd1 through Vd3 at Vd(1,2,3)=5.0V with Id1=100mA, Id2=200mA
and Id3=300mA. Separate biasing is recommended if the amplifier is to be used at high levels of saturation, where gate rectification will alter the
effective gate control voltage. For non-critical applications it is possible to parallel all stages and adjust the common gate voltage for a total drain
current Id(total)=700 mA. It is also recommended to use active biasing to keep the currents constant as the RF power and temperature vary; this
gives the most reproducible results. Depending on the supply voltage available and the power dissipation constraints, the bias circuit may be a
single transistor or a low power operational amplifier, with a low value resistor in series with the drain supply used to sense the current. The gate of
the pHEMT is controlled to maintain correct drain current and thus drain voltage. The typical gate voltage needed to do this is -0.7V. Typically the
gate is protected with Silicon diodes to limit the applied voltage. Also, make sure to sequence the applied voltage to ensure negative gate bias is
available before applying the positive drain supply.
App Note [2] Bias Arrangement -
For Parallel Stage Bias (Recommended for general applications) -- The same as Individual Stage Bias but all the drain or gate pad DC bypass
capacitors (~100-200 pF) can be combined. Additional DC bypass capacitance (~0.01 uF) is also recommended to all DC or combination (if gate or
drains are tied together) of DC bias pads.
For Individual Stage Bias (Recommended for saturated applications) -- Each DC pad (Vd1,2,3 and Vg1,2,3) needs to have DC bypass capacitance
(~100-200 pF) as close to the device as possible. Additional DC bypass capacitance (~0.01 uF) is also recommended.
App Note [3] On Board Detector – The output signal of the power amplifier is coupled via a 15 dB directional coupler to a detector, which
comprises a diode connected to the signal path, and a second diode used to provide a temperature compensation signal. The common bias
terminal is Vdet, and is nominally set to forward bias both diodes. The Vdet port can be connected directly to a 5V bias, and given the internal series
resistance, results in about 1mA of bias current.
App Note [4] Output Power Adjust Using Drain/Gate Control – This device has a very useful additional feature. The output power can be
adjusted by lowering the combined drain voltages and individual or combined gate voltages towards pinch off without sacrificing much in the way
of Input/Output 3rd Order Intercept Point. Improvements to the IIP3/OIP3 while attenuating the gain are also possible with individual gate control.
Data here has been taken using combined drain and gate control (all gates changed together) to lower the device’s output power. The results are
shown below. Additionally, the accompanying graph shows the typical level of attenuation achievable as the drain and gate is adjusted at various
levels until pinch-off.
R10C10_0696ND_C_029BA101 vs Pin: Video (mV) vs. Power out (dBm)
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930
Power out (dBm)
, Input Freq (GHz)=17.5
, Input Freq (GHz)=18
, Input Freq (GHz)=18.5
, Input Freq (GHz)=19
, Input Freq (GHz)=19.5
, Input Freq (GHz)=17.5
, Input Freq (GHz)=18
, Input Freq (GHz)=18.5
, Input Freq (GHz)=19
, Input Freq (GHz)=19.5
, Input Freq (GHz)=17.5
, Input Freq (GHz)=18
, Input Freq (GHz)=18.5
, Input Freq (GHz)=19
, Input Freq (GHz)=19.5
0696ND with BCB: Pout vs. DA Value @ Pin=+5 dBm
Vd123=5 -> 1.5 V, Id1=100 -> 0 mA, Id2=200 -> 0 mA, Id3=400 -> 0 mA
30
25
20
15
10
5
0
-5
-10
-15
-20
-25
-30
16
17
18
19
20
21
22
23
24
Frequency (GHz)
, VDR=1.5
, VDR=1.6
, VDR=1.7
, VDR=1.8
, VDR=1.9
, VDR=2
, VDR=2.1
, VDR=2.2
, VDR=2.3
, VDR=2.4
, VDR=2.5
, VDR=3
, VDR=3.5
, VDR=4
, VDR=4.5
, VDR=5
Mimix Broadband, Inc., 10795 Rockley Rd., Houston, Texas 77099
Tel: [phone] Fax: [phone] mimixbroadband.com
Page 5 of 8
Characteristic Data and Specifications are subject to change without notice. ©2008 Mimix Broadband, Inc.
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