Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – With specific source of supply or bias voltage
Reexamination Certificate
1999-02-03
2001-10-02
Kim, Jung Ho (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
With specific source of supply or bias voltage
Reexamination Certificate
active
06297689
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to voltage references. In particular, the present invention relates to low temperature coefficient low power programmable complementary metal oxide semiconductor (CMOS) voltage references with simple and efficient architecture.
2. Description of the Related Art
Historically, the design of voltage references entailed the use of circuits containing hundreds of transistors. Due to this, the complexity and costs involved in designing such voltage references can be significantly high. Bandgap voltage reference circuits are most commonly used in CMOS mixed signal circuits to provide for a stable voltage reference. A standard bandgap reference such as, for example, LM330 3-Terminal Positive Regulator from National Semiconductor Corporation, has a variation of approximately 0.2% in output voltage over a temperature range from room temperature to 80° C. Moreover, as voltage references, erasable programmable read-only memories (EPROMs) are designed to support leakage on the order of 1 volt over a ten (10) year lifetime.
However, the bandgap circuit has a number of shortcomings. Some of these shortcomings include large dc power consumption, the need for parasitic, and usually unsupported, pnp or npn transistors, and the need to match the base emitter voltage (V
BE
) for these parasitic devices. Additionally, several design iterations are often necessary to get the bandgap circuit to operate due to lack of good models for the second order effects upon which the bandgap performance is based. Moreover, the stability of the bandgap references over time has been a reliability issue for some CMOS products, for example, in telecommunications devices.
SUMMARY OF THE INVENTION
In view of the foregoing, the present invention discloses a low temperature coefficient low power programmable CMOS voltage reference.
In particular, an apparatus including a voltage reference in accordance with one embodiment of the present invention includes a reference terminal; an output terminal; a first transistor having first and second terminals; a second transistor having first and second terminals, said second transistor first terminal coupled to said output terminal; a capacitance coupled between said first transistor first terminal and said reference terminal configured to store a pre-determined reference signal; and a variable signal generator coupled to said second transistor first terminal configured to provide a variable signal and in accordance thereto provide an output signal to said output terminal; wherein said variable signal is configured to vary such that said output signal is substantially equal in magnitude to said predetermined reference signal.
An apparatus including a voltage reference in accordance with another embodiment of the present invention includes a reference terminal; a first transistor having first, second and third terminals; a second transistor having second and third terminals; a capacitance coupled between said first transistor first terminal and said reference terminal, said capacitance configured to store a reference signal; and a programming signal source coupled to said first and second transistor third terminals configured to provide a programming signal thereto, and in accordance therewith, generates said reference signal across said capacitance.
An apparatus including a voltage reference in accordance with yet another embodiment of the present invention includes a reference terminal; an output terminal; a first transistor having first, second and third terminals; a second transistor having first, second and third terminals, said second transistor first terminal coupled to said output terminal; a capacitance coupled between said first transistor first terminal and said reference terminal configured to store a reference signal; a programming signal source coupled to said first and second transistor third terminals configured to provide a programming signal thereto, and in accordance therewith, generating said reference signal across said capacitance; and a variable signal generator coupled to said second transistor first terminal configured to provide a variable signal and in accordance thereto provide an output signal to said output terminal; wherein said variable signal is configured to vary such that said output signal is substantially equal in magnitude to said reference signal.
Accordingly, the present invention provides an architecturally simple and efficient voltage reference. These and other features and advantages of the present invention will be understood upon consideration of the following detailed description of the invention and the accompanying drawings.
REFERENCES:
patent: 5546042 (1996-08-01), Tedrow et al.
patent: 5812021 (1998-09-01), Ikeda
patent: 5914894 (1999-06-01), Diorio et al.
patent: 5936455 (1999-08-01), Kobayashi et al.
patent: 5942936 (1999-08-01), Ricco et al.
Seji Yamada, et al., “Non-uniform Current Flow through Tin Oxide After Fowler-Nordheim Current Stress”, IEEE (May 1996).
Akinobu Teramoto, et al., “Excess Currents Induced by Hot-Hole Injection and F-N Stress in Thin Sio2Films”, IEEE (May 1996).
Kim Jung Ho
National Semiconductor Corporation
Oh Seong-Kun
Sierra Patent Group Ltd.
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