NEAR-FIELD MAPPING ABOVE A COUPLED-LINE FILTER AND A MMIC

This article presents a comparison of the electric field measured with the modulated scattering technique and calculated with finite-differe nce time domain (FDTD) simulations for a three-stage coupled-line micr ostrip bandpass filter. Electrically small dipoles and monopoles 150 a nd 100 mu m long, respectively, are used as modulated scatterers for t he measurements, Tile comparisons are performed at 10 GHz at a mean he ight of 50 mu m above the filter with monolithically integrated Schott ky diode probes on 40 mu m-thick silicon substrates. The electric fiel d map of the tangential field component (measured and simulated) is di splayed with the same scale at 10 GHZ. In addition, the normal electri c field map of a distributed amplifier is presented using the scattere d signal from the output port of the amplifier: The low cost modulated scattering system is capable of mapping the normal and tangential ele ctric field intensifies and electrical phase delays above a microwave circuit in the frequency range Of 0.5 to 18 GHz with a spatial electri c field resolution of better than 100 mu m. This article demonstrates that both the FDTD and modulated scattering techniques are powerful de velopmental fools that can be used together to accurately characterize the behavior of microwave circuits.