Integrated dual charge pump power supply and RS-232 transmitter/receiver
First Claim
1. A circuit, integratable on a single piece of semiconductor substrate material, for providing a bipolar voltage output at substantially double the voltage of a unipolar voltage input source, including:
- first and second voltage input terminals,first and second positive transfer capacitor connection terminals,first MOS semiconductor switch means for selectively connecting said first voltage input terminal to said first positive transfer capacitor connection terminal and said second voltage input terminal to said second positive transfer capacitor connection terminal,first and second positive reservoir capacitor connection terminals, said first positive reservoir capacitor connection terminal connected to a fixed voltage,second MOS semiconductor switch means for selectively connecting said first voltage input terminal to said second positive transfer capacitor connection terminal and said first positive transfer capacitor connection terminal to said second positive reservoir capacitor connection terminal,first and second negative transfer capacitor connection terminals,third MOS semiconductor switch means for selectively connecting said second voltage input terminal to said first negative transfer capacitor connection terminal and said second positive reservoir capacitor connection terminal to said second negative transfer capacitor connection terminal,first and second negative reservoir capacitor connection terminals, said first negative reservoir capacitor connection terminal connected to a fixed voltage,fourth MOS semiconductor switch means for selectively connecting said first negative transfer capacitor connection terminal to said second negative reservoir capacitor connection terminal and said second negative transfer capacitor connection terminal to said second voltage input terminal, andselection means, coupled to said first, second, third and fourth semiconductor switch means, for selectively activating said first, second, third and fourth semiconductor switch means.
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Accused Products
Abstract
A monolithic integrated circuit containing an inverting/non-inverting voltage doubler charge pump circuit is disclosed for converting a unipolar supply voltage to a bipolar supply voltage of a greater magnitude. The unipolar input voltage is placed across a first external transfer capacitor by a first set of MOS switches during a first time period. The unipolar input voltage source is placed in series with the first transfer capacitor and this series combination of voltages is placed across a first external reservoir capacitor by a second set of MOS switches during a second time period. The voltage appearing across the first external reservoir capacitor is placed on a second transfer capacitor during the first time period by a third set of MOS switches. The voltage across the second transfer capacitor is placed into a second external reservoir capacitor with its polarity inverted by a fourth set of MOS switches during the second time period. A dual-collector lateral junction transistor, formed during the conventional CMOS processing steps used to fabricate the MOS switches, is connected as voltage clamp between a ground potential and the two bipolar DC output lines of the power supply circuit to assure correct start-up conditions for the conduit. Gain reduction devices are placed in the semiconductor substrate to collect minority carriers which would otherwise be injected into inherent parasitic four layer PNPN junction devices created as a result of the architecture of the circuit, to prevent latch-up of the four layer devices. In a preferred embodiment, an RS-232 receiver and transmitter are contained on the same monolithic integrated circuit as the dual charge pump power supply.
79 Citations
33 Claims
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1. A circuit, integratable on a single piece of semiconductor substrate material, for providing a bipolar voltage output at substantially double the voltage of a unipolar voltage input source, including:
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first and second voltage input terminals, first and second positive transfer capacitor connection terminals, first MOS semiconductor switch means for selectively connecting said first voltage input terminal to said first positive transfer capacitor connection terminal and said second voltage input terminal to said second positive transfer capacitor connection terminal, first and second positive reservoir capacitor connection terminals, said first positive reservoir capacitor connection terminal connected to a fixed voltage, second MOS semiconductor switch means for selectively connecting said first voltage input terminal to said second positive transfer capacitor connection terminal and said first positive transfer capacitor connection terminal to said second positive reservoir capacitor connection terminal, first and second negative transfer capacitor connection terminals, third MOS semiconductor switch means for selectively connecting said second voltage input terminal to said first negative transfer capacitor connection terminal and said second positive reservoir capacitor connection terminal to said second negative transfer capacitor connection terminal, first and second negative reservoir capacitor connection terminals, said first negative reservoir capacitor connection terminal connected to a fixed voltage, fourth MOS semiconductor switch means for selectively connecting said first negative transfer capacitor connection terminal to said second negative reservoir capacitor connection terminal and said second negative transfer capacitor connection terminal to said second voltage input terminal, and selection means, coupled to said first, second, third and fourth semiconductor switch means, for selectively activating said first, second, third and fourth semiconductor switch means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 14, 16, 17, 18, 19, 20, 21, 22, 23)
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8. A circuit, intergratable on a single piece of semiconductor substrate material, for providing a bipolar voltage output at substantially double the voltage of a unipolar voltage input source, including:
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first and second voltage input terminals, first and second positive transfer capacitor connection terminals, a first set of MOS semiconductor switches, including a switch connected between said first voltage input terminal and said first positive transfer capacitor connection terminal and a switch connected between said second voltage input terminal and said second positive transfer capacitor connection terminal, first and second positive reservoir capacitor connection terminals, said first positive reservoir capacitor connection terminal connected to a fixed voltage, a second set of MOS semiconductor switches, including a switch connected between said first voltage input terminal and said second positive transfer capacitor connection terminal, and a switch connected between said first positive transfer caapacitor connection terminal and said second positive reservoir capacitor connection terminal, first and second negative transfer capacitor connection terminals, a third set of MOS semiconductor switches, including a switch connected between said second voltage input terminal and said first negative transfer capacitor connection terminal and a switch connected between said second positive reservoir capacitor connection terminal and said second negative transfer capacitor connection terminal, first and second negative reservoir capcitor connection terminals, said first negative reservoir capacitor connection terminal connected to a fixed voltage, a fourth set of MOS semiconductor switches, including a switch connected between said first negative transfer capacitor connection terminal and said second negative reservoir capacitor connection terminal and a switch connected between said second negative transfer capacitor connection terminal and said second voltage input terminal, selection means, coupled to said first, second, third and fourth set of semiconductor switches, for selectively activating said first, second, third and fourth sets of semiconductor switches. - View Dependent Claims (9, 10, 11, 12, 13, 15, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification