Voltage-controlled oscillator with stable gain over a wide frequency range
First Claim
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1. A voltage controlled oscillator (VCO), comprising:
- a first bias generator coupled to receive a frequency select input signal and a control input signal, wherein, in operation, the first bias generator uses the frequency select input signal and the control input signal to generate an output bias signal of the first bias generator, wherein the control input signal is a differential voltage input signal and the first bias generator comprises a differential amplifier coupled to receive the differential voltage input signal, the differential amplifier having a gain input signal terminal coupled to receive the frequency select input signal; and
a first waveform generator coupled to receive the output bias signal from the first bias generator, wherein the first waveform generator, in operation, produces an output waveform having a frequency that is determined by the output bias signal.
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Abstract
An apparatus and method for providing a stable gain over wide frequency range in a VCO are presented. A VCO uses a waveform generator along with a bias generator having a frequency select input. The frequency select input is used to adjust the amount of output current and/or gain of the bias generator. The output current of the bias generator determines the frequency of the output of the waveform generator. Multiple bias and waveform generators may be used to expand the frequency range of the VCO. A PLL may be programmed for a variety of output frequencies by using the frequency select input of the VCO.
21 Citations
20 Claims
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1. A voltage controlled oscillator (VCO), comprising:
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a first bias generator coupled to receive a frequency select input signal and a control input signal, wherein, in operation, the first bias generator uses the frequency select input signal and the control input signal to generate an output bias signal of the first bias generator, wherein the control input signal is a differential voltage input signal and the first bias generator comprises a differential amplifier coupled to receive the differential voltage input signal, the differential amplifier having a gain input signal terminal coupled to receive the frequency select input signal; and a first waveform generator coupled to receive the output bias signal from the first bias generator, wherein the first waveform generator, in operation, produces an output waveform having a frequency that is determined by the output bias signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A bias generator for use in a voltage controlled oscillator, comprising:
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a reference circuit including a bias input signal terminal and a gain input signal terminal; a differential amplifier having a gain input signal terminal and an output signal terminal, the output signal terminal being coupled to the bias input signal terminal of the reference circuit; and a first frequency select input signal terminal; and a logic circuit coupled with the first frequency select input signal terminal, the logic circuit including a first output signal terminal connected to the gain input signal terminal of the reference circuit and a second output signal terminal connected to the gain input signal terminal of the differential amplifier. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
a sixth FET having a source and a gate, the source of the sixth FET being coupled to the drain of the fifth FET and the gate of the sixth FET being coupled to the second gain input signal terminal of the reference circuit.
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17. The bias generator of claim 16, wherein first and second frequency select signals are used to turn the bias generator on and off.
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18. A method of providing a stable frequency gain in a voltage controlled oscillator:
- the method comprising;
providing a voltage input signal and a frequency input signal to a differential amplifier within the voltage controlled oscillator; providing an output signal of the differential amplifier to a reference circuit; biasing a waveform generator with an output signal of the reference circuit; adjusting a gain of the differential amplifier using the frequency input signal; adjusting the frequency of an output waveform of the waveform generator using the frequency input signal; providing the waveform output to a logic circuit; and using the logic circuit to select an output signal of the voltage controlled oscillator from a plurality of waveform generators. - View Dependent Claims (19, 20)
- the method comprising;
Specification