An ultra-broad-band reflection-type phase shifter is proposed. Theoretically, the proposed phase shifter has frequency-independent characteristics in the case of 180 phase shift. The phase shifter is composed of a 3-dB hybrid coupler and a pair of novel reflective terminating circuits. The reflective terminating circuit switches two states of series and parallel LC circuits. Using an ideal circuit model without parasitic circuit elements, we have derived the determining condition of frequency independence of circuit elements. Extending the concept, we can also obtain a broad-band phase shifter for other phase difference as well. In this case, for a given phase difference and an operating frequency, we also derive a condition to obtain minimum variation of phase difference around the operating frequency. This enables the broad-band characteristics for arbitrary phase difference. The fabricated 180 reflective terminating circuit monolithic microwave integrated circuit (MMIC) has achieved a phase difference of 183 3 over 0.5-30 GHz. The 180 phase-shifter MMIC has demonstrated a phase shift of 187 7 over 0.5-20 GHz. The 90 reflective terminating circuit MMIC has performed a phase difference of 93 7 over 4-12 GHz.
This paper describes the design, fabrication, and performance of wideband monolithic lossy match power amplifiers employing prematching circuits, which make the frequencydependence of input and output impedance of FETs small. First, it is shown theoretically that a wide bandwidth can be achieved by using prematching circuits in the design of lossy match power amplifiers. Second, a novel constant-resistance network and a parallel resonant circuit are proposed as prematching circuits. Impedance matching methods using prematching circuits are also described. Finally, by employing these prematching circuits in the design and fabrication of a C -K bandpower amplifier, it is experimentally shown that the impedance matching methods using prematching circuits are useful in the design of wideband lossy match power amplifiers. The amplifier exhibits a linear gain of 10 f 2.3 dB, a saturated power of 28.3 f 1 dBm, and a drain efficiency of 12.6 f 2.2 percent over 5 -21 GHz. These measured performances are in good agreement with the calculated results. The prematching circuits, which make the frequencydependence of input and output impedance of FETs small, are useful for achieving a wide bandwidth of lossy match power amplifiers. In addition, the parallel resonant circuit, which comprises only reactive elements, is also useful in the design of output matching circuits for achieving high gain and high power.
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