A generalized method for characterizing two-dimensional scattering problems with spectral techniques

✍ Scribed by H. Esteban; J. M. López; V. E. Boria; M. Baquero; M. Ferrando

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 133 KB
• Volume: 14
• Category: Article
• ISSN: 0895-2477
• DOI: 10.1002/(sici)1098-2760(199701)14:1<6::aid-mop3>3.0.co;2-p

✦ Synopsis

input voltages that provide useful circuit operation. Figure 4 shows the measured return loss of a typical attenuator chip at Ž 7 GHz. Return loss is similar at other frequencies within the . range of 7᎐18 GHz. The lower left region represents the minimum loss state of the attenuator, with series HEMT on and shunt HEMT off. As V is made less negative to increase 2 the attenuation by the shunt HEMTs, V must be made more 1 negative to maintain low return loss. This is easily understood by considering that the behavior of the HEMT varistor ladder network is closely analogous to a resistive tee or pi network. To achieve very high attenuation, V must be increased 2 toward 0 V, whereas V is kept relatively constant. This can 1 also be understood by the resistor network analogy. Although Ž . high ) 50 dB attenuation is achieved in this region, the phase error is large, in the tens of degrees. Low phase error can, however, be achieved, with the chip operated up to an attenuation of 20᎐30 dB.

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