NES1823P-100 Ver la hoja de datos (PDF) - NEC => Renesas Technology
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NES1823P-100 Datasheet PDF : 20 Pages
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NES1823P-100
CIRCUIT DESIGN
The matching circuit of package inside consists of bond-wire, chip-capacitor and microstrip line on the alumina
substrate. The package-lead impedance is designed as 25 Ω connecting to the external matching circuit, in the
external circuit design, the microstrip line impedance is 25 Ω, conjugate with package impedance, then the
impedance is connected to balun, it is 1:2 balun structure, finally connected to 50 Ω. Balun technology has some
advantage over single-ended device, minimize matching-loss with decrease of impedance change ratio and cancel
the even mode harmonic frequency for IM3 performance. The balun circuit is employed for this product.
BALUN DESIGN
The balun design is the key for these high power push-pull structure device. NEC designed low insertion loss
microstrip balun for this product. What is the reason of our choice? One is the repeatability of assembly, and the
other is its performance. Microstrip balun performance tolerance is small because of its simple structure. So the
balun performance is stable and repeatable between NEC and customers. And its insertion loss is 0.2 dB less than
coaxial balun 0.3 dB, also Its band width is better than coaxial balun. The microstrip balun is consists of microstrip
pattern and cavity, therefore its insertion loss and band width due to its parameter design. Those parameters are
optimized with simuration. : (substrate duroid ε r = 2.2 t = 0.8 mm)
Then the phase difference between two ports is 180° ±4, insertion loss is 0.2 dB from 1 to 3 GHz.
DC STABILITY (AVOID OSCILLATION)
The function of DC-cut capacitor arranged between transformer and microstrip balun is avoid DC oscillation.
When the gate is pinch-off, a few pinch-off voltage (VP) difference of each port occur the loop current, then start DC
oscillation in the area of pinch-off. Because of this reasons, the DC-cut capacitor is need to this microstrip balun
assemble. Additionally, the ground of transformer substate is effective to DC oscillation, so that five screws are
arranged at the middle of substrate.
Preliminary Data Sheet
11
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