US 4,733,153 AGranted

Switching system for capacitor charging/discharging

AssigneeBrooktree Corporation

InventorHenry S. Katzenstein

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Abstract

First and second switches such as transistors are connected to a charge storage member such as a capacitance. The capacitance is charged through the first transistor from a positive supply when the transistor becomes conductive. The capacitances is discharged through the second transistor to a reference potential such as ground when the second transistor becomes conductive. The conductivities of the first and second transistors are controlled by pulses from a pulse source such as a transformer. The transformer primary produces a pulse of one polarity upon the occurrence of the leading edge of an input signal and a pulse of an opposite polarity upon the occurrence of the trailing edge of the input signal. Two secondary windings are respectively connected in opposite polarities to the bases of the first and second transistors to provide for the conductivity of only one of the transistors at any one time. The transformers saturate the conductive transistor to prolong on a limited basis the time during which the transistor remains conductive. The other one of the transistors is made instantaneously non-conductive by providing for an instantaneous discharge of the stored base charge between the base and emitter of the transistor. A constant current source is electrically in parallel with the first transistor to sustain the capacitance charge at a high level after the limited period of time in which the first transistor remains conducitive. A low frequency transistor is connected in parallel with the second transistor to sustain the discharge of the capacitance after the limited period of time in which the second transistor remains conductive.

Claims12

Dependent claims

In combination in an electronic switch controlling the charging and discharging of charge storage means having first and second terminals,

means for providing a reference voltage,
means for providing an energizing voltage,
first switching means connected to the first terminal of the charge storage means and the energizing voltage means and having open and closed states and operative in the open state to prevent the energizing voltage from being introduced to the charge storage means and operative in the closed state to provide for the introduction of the energizing voltage to the charge storage means to charge the charge storage means,
second switching means connected to the first terminal of the charge storage means and the reference voltage means and having open and closed states and operative in the open state to prevent the discharge of the charge storage means and operative in the closed state to provide for the discharge of the charge storage means through the reference voltage means,
means for providing an input signal having leading and trailing edges,
means responsive to the leading edge of the input signal for instantaneously pulsing the first switching means to the closed state and the second switching means to the open state and for maintaining the first switching means in the closed state and the second switching means in the open state for a particular period of time after the leading edge of the input signal,
means for maintaining a substantially constant flow of current to the charge storage means after the particular period of time in which the first switching means is closed,
the pulsing means being responsive to the trailing edge of the input signal for instantaneously pulsing the first switching means to the open state and the second switching means to the closed and for maintaining the first switching means in the open state and the second switching means in the closed state for the particular period of time after the trailing edge of the input signal, and
third switching means having slower response characteristics than the second switching means for maintaining the discharge of the charge storage means to the reference voltage means after the particular period of time in which the second switching means is closed.

6 more elements

In combination in an electrical switch for controlling the charging and discharging of charge storage means,

means for providing an energizing voltage,
means for providing a reference voltage,
a first transistor having conductive and non-conductive states,
first circuitry including the energizing voltage means, the first transistor and the reference voltage means for providing a charging of the in the conductive state of the first transistor,
a second transistor having conductive and non-conductive states,
second circuitry including the second transistor and the reference voltage means for providing a discharge of the charge storage means in the conductive state of the second transistor,
means for providing an input signal having leading and trailing edges,
means responsive to the leading edge of the input signal for instantaneously triggering the first transistor to the conductive state and the second transistor to the non-conductive state and responsive to the trailing edge of the input signal for instantaneously triggering the first transistor to the non-conductive state and the second transistor to the conductive state and for maintaining the transistors in their respective states after such triggerings,
means responsive to the triggering of the first transistor to the conductive state for prolonging the charging of the charge storage means after such triggering, and
means responsive to the triggering of the second transistor to the conductive state for prolonging the discharge of the charge storage means after the particular period.

7 more elements

In combination in an electronic switch for controlling the charging and discharging of a capacitance,

first switching means having open and closed states and connected to the capacitance to produce a charging of the capacitance in the closed state of the first switching means,
second switching means having open and closed states and connected to the capacitance to produce a discharge of the capacitance in the closed state of the second switching means,
means for providing input signals having leading and trailing edges,
means responsive to the leading edges of the input signals for producing first pulses extended for a first limited period of time beyond the leading edges to close the first switching means and open the second switching means during such first limited period of time,
means responsive to the trailing edges of the input signals for producing second pulses extended for a second limited period of time beyond the trailing edges to close the second switching means and open the first switching means for such second limited period of time,
means operatively coupled to the capacitance for producing an additional charge of the capacitance after the closure of the first switching means for the first limited period of time and until the occurrence of the next trailing edge in the input signals, and
means operatively coupled to the capacitance for producing an additional discharge of the capacitance after the closure of the second switching means for the limited period of time and until the occurrence of the leading edge in the next one of the input signals.

4 more elements

Dependencies are inferred from the claim text.