Circuit arrangement for generating a control signal in dependence upon the occurrence of an extreme value of a sinusoidal oscillation and use of such a circuit arrangement

• US 5,126,745 A
• Filed: 04/27/1990
• Issued: 06/30/1992
• Est. Priority Date: 05/05/1989
• Status: Expired due to Term

• Current Assignee: Texas Instruments Deutschland Gesellschaft Mit Beschrã¤Nkter Haftung (Texas Instruments, Inc.)
• Original Assignee: Texas Instruments Deutschland Gesellschaft Mit Beschrã¤Nkter Haftung (Texas Instruments, Inc.)
• Inventors: Kaiser, Ulrich, Steinhagen, Wolfgang
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US07/515,374
• Time in Patent Office: 795 Days
• Field of Search: 342/51, 340/825.54, 340/572, 331/172
• US Class Current: 342/51
• CPC Class Codes: H03B 11/04 excited by interrupter

Abstract

A circuit arrangement is described with the aid of which a control signal can be generated in dependence upon the occurrence of an extreme value of a sinusoidal oscillation. The circuit arrangement (10) includes a storage member (22) which is adapted to be charged via a diode (20) to one of the extreme values of the sinusoidal oscillation. A discharge path (26) for the storage member (22) is present, the time constant of which is so dimensioned that within the period duration of the sinusoidal oscillation an appreciable discharge of the storage member (22) takes place. A switch element (24) controllable by the charge voltage of the storage member (22) furnishes the control signal at its output (14) for the period of time during which the charge voltage at the storage member (22) is smaller than the extreme value of the sinusoidal oscillation. The circuit arrangement can be used in maintaining the oscillations of a resonance circuit stimulated to oscillate by means of a momentary HF carrier wave pulse.

Claims

1. A system for maintaining the sinusoidal oscillations of a resonance circuit comprising:

a diode for rectifying a sinusoidal oscillation;

a storage element suitable for charging to an extreme voltage value of a sinusoidal oscillation through said rectifying diode;

a discharge path for substantially discharging said storage element during the period of the sinusoidal oscillation;

a switch element for furnishing a control signal as said storage element is being charged to said extreme voltage of the sinusoidal oscillation, and;

a series circuit, comprising a resonant circuit and a controllable switch, said series circuit connected in parallel to said storage element, said control signal switching said controllable switch to a conductive position thereby supplying said resonant circuit with supply voltage.

2. The system according to claim 1, wherein said resonant circuit comprises a parallel combination of a coil and a capacitor.

3. System according to claim 2, wherein said coil is a receiving coil in the receiving section of a transponder, and said receiving coil receives a carrier wave pulse.

4. A system according to claim 3, wherein at the termination of said carrier wave pulse, oscillations in the resonance circuit are maintained by said control signal and said oscillations generate clock pulses in the transponder.