Integrated circuit

Details Integrated circuit Integrated circuit

2000-07-14

2003-06-10

Pascal, Robert (Department: 2817)

Wave transmission lines and networks

Negative resistance or reactance networks of the active type

Simulating specific type of reactance

C333S213000

Reexamination Certificate

active

06577212

ABSTRACT:

This application claims priority under 35 U.S.C. §§119 and/or 365 to 99688.0 filed in Great Britain on Jul. 16, 1999; the entire content of which is hereby incorporated by reference.
TECHNICAL FIELD
This invention relates to integrated circuits, and in particular to integrated analog filter circuits.
BACKGROUND OF THE INVENTION
In integrated circuits, it is extremely difficult to realise inductors, except with very low inductances. As a result, it is generally only possible to use RC filters (with resistors and capacitors), except at very high frequencies.
As an alternative, active filters are often used. Such devices use transconductance elements such as transistors, in combination with capacitors, which together can form integrators or gyrators, and can emulate the impedance of inductors.
An integrated gyrator structure, for use in a very high frequency filter, is proposed in Nauta “A CMOS Transconductance-C Filter Technique for Very High Frequencies”, IEEE Journal of Solid State Circuits, Vol. 27, No. 2, February 1992. The author's first order analysis of the circuit concluded that the proposed gyrator behaves stably.
The author also proposed a Q-tuning loop, to provide a controllable Q-value for the filter at very high frequencies.
SUMMARY OF THE INVENTION
The present invention proceeds from the realization that this first order analysis of the prior art structure results in an incomplete understanding of the structure.
In particular, a more detailed analysis of the MOS transistors reveals that each MOS transistor adds a delay element due to the actions of charged particles in the channel of the transistor. More specifically, the nonquasi-static behaviour of the channel charge adds a delay, which could be approximated as a parasitic pole, in the frequency characteristic of the transconductance of the device. The channel delays of the transistors can make the gyrator unstable, in particular in the case of higher order filters (which are often required, in order to provide the necessary filter characteristics), or at higher frequencies (when the channel delay becomes more of a problem).
Moreover, the channel delay means that the prior art Q-tuning loop does not function as intended.
The present invention attempts to overcome the disadvantages of the prior art, by taking the channel delay of the transistors into consideration.
Specifically, the invention relates in one aspect to the design of an integrated circuit device, in a way which includes consideration of the channel delay of the transistors.
In another aspect, the invention relates to an integrated circuit device, in which the channel delay of a transistor is compensated by means of series feedback.
In another aspect, the invention relates to the design method, which accounts for the channel delay.


REFERENCES:
patent: 3840829 (1974-10-01), Fletcher et al.
patent: 4565962 (1986-01-01), Nagano
patent: 5117205 (1992-05-01), Nauta
patent: 5371475 (1994-12-01), Brown
patent: 1120592 (1968-07-01), None
patent: 1277495 (1972-06-01), None
patent: 1405232 (1975-09-01), None
patent: 1531447 (1978-11-01), None
patent: 2049332 (1980-12-01), None
patent: 2049333 (1980-12-01), None
patent: 2307124 (1997-05-01), None
patent: W90/12454 (1990-10-01), None
Jacob Millman, Microelectronics: Digital and Analog Circuits and Systems 1979, McGraw-Hill, pp. 397-399.*
International Search Report, Oct. 20, 2000, Telefonaktiebolaget L M Ericsson, PCT/EP00/06344.
British Search Report, Feb. 9, 2000, Telefonaktiebolaget L M Ericsson, GB9916808.0.
“Analog CMOS Filters for Very High Frequencies”, The Kluwer International Series in Engineering and Computer Science, vol. 190; Bram Nauta, Philips Research Laboratories, Eindhoven, the Netherlands.
A CMOS Transconductance-C Filter Technique for Very High Frequencies; IEEE Journal of Solid-State Circuits, vol. 27, No. 12, Feb. 1992; Bram Nauta.
Active filters: part 10 Synthetic inductors from gyrators; Electronics, Jul. 7, 1969, Gerald Aaronson, General Telephone & Electronics Laboratories Inc., Bayside, NY.

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