Minimization of the power consumption in an oscillator
First Claim
1. A method for controlling a current (Ib) of a voltage controlled oscillator of an oscillator circuit to maintain the current (Ib) at a predetermined level, comprising the steps of:
- generating a DC voltage control signal which is proportional to an output level of the oscillator;
applying the generated DC voltage control signal in a negative feedback loop to a circuit element (FET1) for a controlling of the current of the oscillator;
providing an isolating amplifier for the oscillator, the isolating amplifier having a first transistor, the oscillator having a second transistor;
arranging said first and said second transistors in a series circuit allowing said current (Ib) to flow through said first and said second transistors;
connecting said circuit element (FET1) to one of said first and said second transistors;
controlling the current (Ib) by the circuit element (FET1); and
detecting said output level of the oscillator at said isolating amplifier for reducing a required magnitude of supply voltage to the series circuit.
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Accused Products
Abstract
A method is presented for minimizing the current consumption and the operating voltage of a voltage controlled oscillator. According to the invention the oscillator'"'"'s (Q2) output signal (RFout) is detected as a DC voltage signal (Vgs) in a clamp/voltage multiplier circuit (U1, U2), preferably after a isolating amplifier (Q1). This detected signal is supplied in a feedback loop to a field effect transistor (FET1) controlling the oscillator'"'"'s (Q2) current, whereby the field effect transistor controls the current (Ib) in the main current path to a predetermined minimum value. In this superimposed arrangement of the oscillator and the isolating amplifier the supply voltage (B) can be minimized by arranging, regarding the DC current, the isolating amplifier (Q1) in parallel with the field effect transistor (FET1) in the emitter branch of the oscillator (Q2).
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Citations
11 Claims
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1. A method for controlling a current (Ib) of a voltage controlled oscillator of an oscillator circuit to maintain the current (Ib) at a predetermined level, comprising the steps of:
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generating a DC voltage control signal which is proportional to an output level of the oscillator; applying the generated DC voltage control signal in a negative feedback loop to a circuit element (FET1) for a controlling of the current of the oscillator; providing an isolating amplifier for the oscillator, the isolating amplifier having a first transistor, the oscillator having a second transistor; arranging said first and said second transistors in a series circuit allowing said current (Ib) to flow through said first and said second transistors; connecting said circuit element (FET1) to one of said first and said second transistors; controlling the current (Ib) by the circuit element (FET1); and detecting said output level of the oscillator at said isolating amplifier for reducing a required magnitude of supply voltage to the series circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A control circuit for controlling current (Ib) of a voltage controlled oscillator circuit, comprising:
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an isolating amplifier for isolating an output signal of said oscillator circuit from a load, and having a first transistor, wherein said oscillator circuit comprises a second transistor connected serially with said first transistor for allowing said current (Ib) to flow through said first and said second transistors; a controllable means (FET1) controlling the current (Ib); a detection circuit at an output of the isolation amplifier, for detecting the oscillator output signal as a DC voltage control signal; wherein the voltage control signal is supplied in a feedback branch as a control signal to the means (FET1) controlling the current; and the control circuit further comprises a scaling circuit (R4, R7;
R8, R9) in the feedback branch dimensioned so that the current (Ib) obtains a predetermined minimum value in an active balanced state. - View Dependent Claims (9, 10, 11)
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Specification