Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – With specific source of supply or bias voltage
Patent
1994-02-22
1995-08-22
Popek, Joseph A.
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
With specific source of supply or bias voltage
327540, 327543, 365226, 365227, 36518907, 36518909, H03L 500
Patent
active
054444128
DESCRIPTION:
BRIEF SUMMARY
The invention relates to electrically programmable memories in integrated circuit form, generally known as "EEPROM memories" or "EPROM memories" depending on whether or not they are electrically erasable, or again "flash EPROM" memories when they are erasable in blocks.
To program these memories, it is generally necessary to have a voltage known as the "programming voltage" Vpp available in the integrated circuit. This programming voltage is substantially higher than the normal supply voltage Vcc of the circuit. For example, Vcc is usually equal to 5 volts and Vpp is 15 volts or more.
In certain memories, the programming voltage Vpp is given by an external supply. However, this necessitates a specific additional supply terminal for the integrated circuit. The additional terminals add to the cost of the integrated circuit, and it is preferable to avoid them. In certain applications, in any case, the number of terminals is laid down (for example: chip cards with six or eight terminals) and there is no was to add another one. In other applications, there may even be no external supply terminals (for example, a chip card without contact whose operating power is provided by an electromagnetic means).
This is why integrated memories are proposed in which the programming voltage Vpp is produced right inside the integrated circuit, from the normal supply voltage Vcc. To this end, the circuit used is one that is conventionally called a load pump or voltage raiser that receives Vcc and sets up a voltage Vpp greater than Vcc.
The raising circuits are standard ones: a basic raising stage uses simply switches, two capacitors and a two-phase clock to actuate the switches. In a first step, the first capacitor is charged to 5 volts, and then it is discharged into the second capacitor. Then a cycle starts again: a first step of charging the first capacitor to 5 volts and a second step of discharging it into the second capacitor (this time, the second capacitor is already partially charged); the voltage at the terminals of the second capacitor then increases at each clock stroke. Within a few two-phase clock strokes, a voltage that is thrice Vcc is reached in the second capacitor. With two stages, the voltage Vcc is multiplied by 4 within a few clock strokes etc.
The level of output voltage from the raising circuit, available at a capacitor, is kept at a fixed value by a regulator. This regulator may be constituted by a line of transistors that are mounted as diodes so that each one sets up a voltage equal to its threshold voltage between its source and its drain. Depending on the technology implemented, the threshold voltage varies and the number of series-connected transistors generates the regulated voltage at output of the regulator.
For example, with transistors having a threshold voltage on the order of one volt, 16 transistors are needed to set up a regulated voltage Vpp on the order of 16 volts.
A major drawback of existing circuits is their consumption of substantial levels of current, due to the consumption by the load pump itself as well as to that of the regulator. Now it is generally desired to lower this consumption. Furthermore, in certain cases, it is absolutely indispensable to find approaches that minimize consumption: for example, in the case of integrated circuits for "contact-free" chip cards.
It is an aim of the invention to propose a circuit for the generation of programming voltage Vpp that consumes less than the prior art circuits and that furthermore has a good price/quality ratio, with regard to the reliability of operation and the space taken up by the circuit.
More generally, an aim of the invention is to propose a new circuit for the production of a regulated voltage, whether or not this is for a programmable memory.
According to the invention, the circuit for the generation of a voltage Vpp comprises a load pump, a regulation circuit capable of stopping the load pump when the voltage Vpp gets higher than a determined threshold, means to interrupt the current consumption of the regulation circu
REFERENCES:
patent: 4533846 (1985-08-01), Simko
patent: 4952821 (1990-08-01), Kokubun
patent: 5168174 (1992-12-01), Naso et al.
patent: 5175706 (1992-12-01), Edme
patent: 5291446 (1994-03-01), Van Buskirk et al.
Gemplus Card International
Popek Joseph A.
Tran Andrew Q.
LandOfFree
Programming voltage regulation circuit for programmable memories does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Programming voltage regulation circuit for programmable memories, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Programming voltage regulation circuit for programmable memories will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2144793