Photoconductive circuit element reflectometer

Claim 1

A photoconductive reflectometer for characterizing a high-frequency semiconductor device by generating a slowed-motion image of a signal reflected from the device, comprising: pulse means for generating extremely short electrical pulses for reflection by said device; a plurality of photoconductive circuit elements intermediate said pulse means and said device at locations effective to admit samples of electrical signals between said pulse means and said device; a plurality of filter means connected to said plurality of photoconductive circuit elements for electronically filtering out high-frequency components from said samples and for outputting filtered samples in the form of slowed-motion images of said signals between said pulse means and said device; and optical excitation means for sequentially exciting said plurality of photoconductive circuit elements for extremely short periods and at intervals effective for said admissions.

Claim 13

A method of electronically characterizing semiconductor devices or circuits at millimeter wavelength frequencies through analysis of slowed-motion images of the signals reflected from such devices, comprising: focusing a first series of laser light pulses on a first photoconductive circuit element biased by a direct current voltage from a voltage source, thereby producing a series of electrical pulses with pulse widths of approximately 2 ps; conditioning said electrical pulses to improve the frequency related amplitude characteristics of said electrical pulses; propagating said conditioned electrical pulses along a transmission line to a semiconductor device under test; admitting samples of the signals propagating along said transmission line means through a plurality of second photoconductive circuit elements coupled to said transmission line and modulated into very short periods of conductance by a second series of extremely short laser light pulses spaced apart in time a determinable period from said first laser light pulses and focused on said plurality of photoconductive circuit elements; electronically filtering out high-frequency components from said samples admitted by said plurality of second photoconductive circuit elements; and outputting said samples in the form of slowed-motion images of said signals propagating along said transmission line.

Claim 14

A method of electronically characterizing semiconductor devices or circuits at millimeter wavelength frequencies through analysis of slowed-motion images of the signals reflected from such devices, comprising: focusing a first series of laser light pulses on a first photoconductive circuit element biased by a direct current voltage from a voltage source, thereby producing a series of electrical pulses with pulse widths of approximately 2 ps; conditioning said electrical pulses to improve the frequency related amplitude characteristics of said electrical pulses; propagating said conditioned electrical pulses along a transmission line to a semiconductor device under test; admitting samples of the signals propagating along said transmission line means through a plurality of second photoconductive circuit elements coupled to said transmission line and modulated into very short periods of conductance by a second series of extremely short laser light pulses spaced apart in time a determinable period from said first laser light pulses and focused on said plurality of photoconductive circuit elements; electronically filtering out high-frequency components from said samples admitted by said plurality of second photoconductive circuit elements; and outputting said samples in the form of slowed-motion images of said signals propagating along said transmission line.