Electric power conversion systems – Current conversion – With voltage multiplication means
Patent
1995-01-03
1996-01-09
Wong, Peter S.
Electric power conversion systems
Current conversion
With voltage multiplication means
307110, H02M 307
Patent
active
054834341
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a high voltage generator comprising a first series of voltage multiplying stages, each stage comprising a diode and a capacitor one terminal of which being connected to the cathode of the respective diode, wherein every cathode of a diode is connected to the anode of the diode of the next voltage multiplying stage, a clock generator which is able to generate clock pulses being 180.degree. out of phase with one another and being supplied alternately to the other terminal of the capacitors of successive voltage multiplying stages, the last diode in the series having a high voltage output and said high voltage output being connected to feed-back means, which modifies said two clock pulses in dependence on the voltage on the high voltage output.
DESCRIPTION OF THE PRIOR ART
Such a high voltage generator is known from the European patent application 0,350,462. Said known high voltage generator generates a high voltage pulse for instance to program (E)EPROM-memory cells. Therefore, a voltage of about 5 V is converted in a pulse of about 16 V, which value is sufficient to program (E)EPROM-memory cells. Every voltage multiplying stage functions as a charge pump and after each stage a voltage increase at most equal to the step value of the clock pulse less the threshold voltage of the diodes occurs.
A disadvantage of said known arrangement is that the high voltage output shows spikes whenever one of both clock pulses switches.
Japanese patent application JP-A-56.094962 discloses a transformerless type DC/DC converter which is controlled by two reverse-phased clock pulses .phi..sub.1 and .phi..sub.2. The output voltage of the output terminal is entirely determined by PWM-control of the two reverse-phased clock pulses.
U.S. Pat. No. 5,036,229 discloses an arrangement comprising multiple multiplier stages in a charge pump, which multiplier stages are controlled by clock pulses. The application of several charge pumps in parallel are described.
SUMMARY OF THE INVENTION
The object of the invention is to provide an arrangement neutralizing the disadvantage related to the prior art and the output voltage of which does not show any spikes any more.
The arrangement according to the invention is therefore characterized in that at least the last capacitor of the multiplying stages is connected to a junction in order to be supplied with a control voltage during operation, said junction being connected to an input of a control circuit having two outputs, said junction also being connected to current charging means, which is controlled by one of said two outputs of the control circuit and by the feed-back means, and to current discharge means controlled by the other of said two outputs of the control circuit, in such a way that when, during operation, the control voltage increases to a first predetermined level the control circuit operates to deactivate said current charging means and to activate said current discharge means, and when the control voltage decreases to a second predetermined level the control circuit operates to deactivate said current discharge means and to activate said current charging means.
By shaping the current supplied by the current charge means and the current lead away by the current discharge means in a proper way the spikes on the high voltage output may be substantially reduced.
In a first embodiment of the invention only said capacitor in said last voltage multiplying stage is connected to said junction to receive said control voltage.
In a preferred embodiment of the invention the high voltage generator is characterized in that said feed-back means comprises a high voltage feed-back circuit connected to the high voltage output, in that the output of the high voltage feed-back circuit is connected to the input of an operational amplifier the other input of which is connected to a reference voltage, in that the current charge means comprises a current source controlled by an output of the operational amplifier, and a first switch which is co
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patent: 4979088 (1990-12-01), Misaki et al.
patent: 5006974 (1991-04-01), Kazerounian et al.
patent: 5036229 (1991-07-01), Tran
patent: 5175706 (1992-12-01), Edme
patent: 5412257 (1995-05-01), Cordoba et al.
Berhane Adolf
Wong Peter S.
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