Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – Utilizing two electrode solid-state device
Patent
1995-02-06
1997-10-21
Callahan, Timothy P.
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
Utilizing two electrode solid-state device
327493, 327503, 327504, 327583, H03K 500, H03B 712
Patent
active
056800738
DESCRIPTION:
BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to semiconductor devices and, more particularly, to a new class of semiconductor devices known as "controlled" semiconductor capacitors (CC's), in which the capacitance can be varied using an external control agent such as current or a form of radiation, such as light.
Various attempts have been made to develop devices which include the high-speed control of a capacitance by an external source. To date, these attempts have been largely unsuccessful.
Well known in the art are varactors, in which the capacitance is controlled by a voltage. However, varactors provide only a partial solution since their basis of operation inherently restricts the range of the maximum to minimum capacitance ratios (C.sub.max /C.sub.min) obtainable in a narrow range of voltage changes, and their operating voltage is relatively low.
Also known are certain novel and rather exotic devices which are based on quantum well technologies. However, the performance of these devices also leaves much to be desired.
There is thus a widely recognized need for, and it would be highly advantageous to have, capacitors in which the capacitance can be changed over a wide range at a fixed applied voltage by the action of external factors, such as current or radiation, and the like, and which will feature performance which significantly exceeds that possible with presently known devices.
SUMMARY OF THE INVENTION
According to the present invention there is provided a controlled capacitor system, comprising: (a) a capacitor element; and (b) a diode element connected in series with the capacitor element, the diode element being forward-biased, the system being further characterized in that: (i) the diode element has a capacitance which is less than the capacitance of the capacitor element when the diode element is under zero bias; (ii) the capacitance of the diode element is controlled by varying the forward current through the diode element; and (iii) the forward current acting to control the capacitance of the diode element is selected such that the capacitance of the diode element is smaller than the capacitance of the capacitor element when the current through the diode element is below a minimum value; and (iv) the capacitance of the diode element is bigger than the capacitance of the capacitor element when the current through the diode element exceeds a maximum value.
According to further features in preferred embodiments of the invention described below, the diode element or capacitor is shunted by a device selected from the group consisting of a variable resistor, a reverse-biased diode, a photodiode, a photoresistor and a radiation sensor.
According to still a further embodiment according to the present invention, the capacitor element is a reverse-biased diode.
According to features of a preferred embodiment of the present invention the diode element is a GaAs P.sup.+ PiN diode fabricated on a P.sup.+ substrate having a carrier concentration in the i-region of less than 10.sup.12 cm.sup.-3.
The present invention successfully addresses the shortcomings of the presently known configurations by providing a controlled capacitor system which operates over a wide range of operating parameters and which features performance parameters which are significantly superior to those of presently known devices.
In principle, capacitance control can be effected using various combinations of traditionaI discrete elements such as semiconductor diodes arranged in suitable electrical circuits. However, the performance parameters of such devices, particularly in silicon, prevent a practical realization of such schemes or lead to schemes which are uneconomical.
According to the present invention, controlled capacitors can be fabricated using various techniques and devices. Preferably, these include using GaAs PiN diodes having a near-fully compensated i-region of controllable width, either alone or in combination with high-voltage GaAs Schottky diodes.
It appears that the most effective use of
REFERENCES:
patent: 2723355 (1955-11-01), Graham
patent: 2917717 (1959-01-01), Thorsen
patent: 3123723 (1964-03-01), Wieder
patent: 3162817 (1964-12-01), MacIntyre
patent: 3167730 (1965-01-01), Anderson
patent: 3289065 (1966-11-01), Dehmelt et al.
patent: 3374366 (1968-03-01), Kleinberg
patent: 3519330 (1970-07-01), Heilmeier
patent: 3654498 (1972-04-01), Chapron
patent: 3860915 (1975-01-01), Geier et al.
patent: 3911298 (1975-10-01), Borsdorf et al.
patent: 3943381 (1976-03-01), Uchidoi
patent: 4032802 (1977-06-01), Pan et al.
patent: 4156838 (1979-05-01), Montague
patent: 4191899 (1980-03-01), Tomczak et al.
patent: 4387386 (1983-06-01), Graver
patent: 4486722 (1984-12-01), Landt
patent: 4574201 (1986-03-01), Ohyama et al.
patent: 4638269 (1987-01-01), Dawson et al.
patent: 4675628 (1987-06-01), Rosen
patent: 4738933 (1988-04-01), Richards
patent: 4937639 (1990-06-01), Yao et al.
patent: 5148267 (1992-09-01), Ty Tan et al.
patent: 5166083 (1992-11-01), Bayraktaroglu
patent: 5343070 (1994-08-01), Goodrich et al.
Microelectronic Circuits by Sedra/Smith 1991, pp. 96-99, 175-181, 343-345.
Electronic Circuits by Donald L. Schilling 1989, pp. 41-45, 51-54.
The PN Junction Diode Gerold W. Neudeck. Robert F. Pierret, Feb. 1989.
Noise Isolation Switch for Commercial Broadband Power Amplifiers Used in Pulsed NMR (R.E. J Sears.)--Sep. 26, 1980.
Ashkinazi German
Meyler Boris
Nathan Menachem
Zolotarevski Leonid
Zolotarevski Olga
Callahan Timothy P.
Friedman Mark M.
Lam T. T.
Ramot University Authority for Applied Research & Industrial Dev
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