RMDA20420 Просмотр технического описания (PDF) - Raytheon Company
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RMDA20420 Datasheet PDF : 13 Pages
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RMDA20420
RF Components 20-42 GHz General Purpose MMIC Amplifier
ADVANCED INFORMATION
Application
Information
multiplier
operation
Even Harmonic Operation
Even harmonics are generated whenever the symmetry of the input signal waveform is distorted. This
is accomplished by biasing the first stage operating point in a region of the I-V curve where the device
is near pinch-off. In this condition, the first stage becomes a half wave rectifier where conduction only
occurs on positive half cycles of the input waveform. Thus, presenting an asymmetrical waveform
consisting mainly of positive half cycles which is rich in even harmonics to the remaining stages of the
amplifier.
For most even harmonic multiplier operations, the first stage is usually pinched off and the remaining
stages are biased as a linear amplifier. As an example, the RMDA20420 was evaluated as a doubler.
In the doubler operation, two drain voltages of +3.5V were used: One for first stage (Vd1) and the other
(Vd2) for the remaining 3 stages tied together as shown in Figure 2. Independent biasing of the first
stage was achieved by using two separate gate voltages. Vg1 was used for stage one and set to Vg1=-
1.0V (near pinch-off). Vg2 was used for the remaining three stages. Vg2 was adjusted until Idq=330mA.
Vd1
Vd2
RF IN
Vd1
Vg2 alt
Vd2
Vd3
Vd4
Vg1
Vg2
Vg3
Vg4
RF OUT
Vg1
Vg2
Figure 2. RMDA20420 configured as doubler.
For each input frequency and input power level, Vg1 was adjusted to peak the second harmonic. Small
changes in Vg2 and Vd2 at this point help in suppressing odd harmonics. Figure 3 shows the doubler
performance over the 20 to 42 GHz band for a fixed input power level of +12 dBm. The graph shows
doubled frequencies with output power levels greater than +16dBm over the 20-42 GHz band. The
graph also shows the increasing power level of the fundamental at the higher end of the band since the
fundamental frequency approaches the lower band edge of the amplifier passband. Based on these
measurements the RMDA20420 can be used a doubler to give desired frequencies anywhere in the 20-
42 GHz band with a conversion gain up to 8 dB and second harmonic power levels up to 20 dBm.
www.raytheonrf.com
Specifications are based on most current or latest revision.
Revised February 6, 2003
Page 11
Raytheon RF Components
362 Lowell Street
Andover, MA 01810
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