On-chip voltage controlled oscillator
First Claim
Patent Images
1. A circuit comprising:
- a voltage regulator for rejecting low frequency noise from a regulated power supply, the voltage regulator including a voltage regulator output for providing a noise-attenuated regulated voltage; and
an oscillator, the voltage regulator and the oscillator implemented on a common substrate, the oscillator coupled to the voltage regulator output,the voltage regulator further including attenuation means, which attenuation means includes a passive filter coupled to the regulated power supply for attenuating high frequency noise from the regulated power supply, and for supplying power from the power supply to the voltage regulator,wherein the passive filter includes a first resistor-capacitor pair for attenuating noise frequencies higher than a response ability of the voltage regulator, wherein the noise frequencies are higher than about 5 MHz, the passive filter further including a second resistor-capacitor pair for attenuating noise frequencies higher than about 800 MHz,wherein the attenuation means further includes means for maintaining an attenuation of at least about -30 dB for noise frequencies in a range from about DC to at least about 800 MHz,wherein the voltage regulator further includes a band gap circuit and regulator means for providing adequate current to maintain the regulated voltage while preventing noise from passing through the regulator means to the voltage regulator output, the regulator means including a Darlington pair coupled to the voltage regulator output, and a control terminal of the Darlington pair coupled to the band gap circuit for receiving variable current, the band gap circuit coupled to the voltage regulator output and controlling the variable current in response to changes in the regulated voltage,wherein the oscillator comprises a multivibrator which includes a control voltage input, and capacitors connected in parallel, wherein a top plate of one of the capacitors is connected to a bottom plate of another one of the capacitors for providing a symmetric capacitance, and further wherein the control voltage input comprises a first transistor for receiving a control voltage signal, the first transistor coupled to the regulated power supply and to one end of a resistor, another end of the resistor coupled to both a collector and a base of a second transistor, the second transistor coupled to a plurality of transistors to form a multiple output current mirror, the multiple output current mirror coupled to the capacitors connected in parallel.
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Abstract
An on-chip voltage controlled oscillator for use in an analog phase locked loop receives power from a voltage regulator which greatly reduces the noise seen by the voltage controlled oscillator. The voltage controlled oscillator has a DC bias section which supplies a relatively constant current to the multivibrator to assure a minimum operating frequency. A control signal is used to provide additional current which increases the speed of oscillation. The bias current reduces the transfer characteristics (MHz/volt) of the voltage controlled oscillator making it more immune to noise in the control signal.
147 Citations
20 Claims
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1. A circuit comprising:
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a voltage regulator for rejecting low frequency noise from a regulated power supply, the voltage regulator including a voltage regulator output for providing a noise-attenuated regulated voltage; and an oscillator, the voltage regulator and the oscillator implemented on a common substrate, the oscillator coupled to the voltage regulator output, the voltage regulator further including attenuation means, which attenuation means includes a passive filter coupled to the regulated power supply for attenuating high frequency noise from the regulated power supply, and for supplying power from the power supply to the voltage regulator, wherein the passive filter includes a first resistor-capacitor pair for attenuating noise frequencies higher than a response ability of the voltage regulator, wherein the noise frequencies are higher than about 5 MHz, the passive filter further including a second resistor-capacitor pair for attenuating noise frequencies higher than about 800 MHz, wherein the attenuation means further includes means for maintaining an attenuation of at least about -30 dB for noise frequencies in a range from about DC to at least about 800 MHz, wherein the voltage regulator further includes a band gap circuit and regulator means for providing adequate current to maintain the regulated voltage while preventing noise from passing through the regulator means to the voltage regulator output, the regulator means including a Darlington pair coupled to the voltage regulator output, and a control terminal of the Darlington pair coupled to the band gap circuit for receiving variable current, the band gap circuit coupled to the voltage regulator output and controlling the variable current in response to changes in the regulated voltage, wherein the oscillator comprises a multivibrator which includes a control voltage input, and capacitors connected in parallel, wherein a top plate of one of the capacitors is connected to a bottom plate of another one of the capacitors for providing a symmetric capacitance, and further wherein the control voltage input comprises a first transistor for receiving a control voltage signal, the first transistor coupled to the regulated power supply and to one end of a resistor, another end of the resistor coupled to both a collector and a base of a second transistor, the second transistor coupled to a plurality of transistors to form a multiple output current mirror, the multiple output current mirror coupled to the capacitors connected in parallel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A circuit comprising:
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a voltage regulator coupled to a power supply and including a voltage regulator output for providing a regulated voltage, wherein the voltage regulator includes a passive filter coupled to the power supply for attenuating high frequency noise, the passive filter including a first resistor-capacitor pair for attenuating noise frequencies higher than a response ability of the voltage regulator and a second resistor-capacitor pair for attenuating noise frequencies higher than about 800 MHz; and an oscillator, the voltage regulator and the oscillator being implemented on a common substrate, the oscillator coupled to the voltage regulator output, wherein the oscillator comprises a multivibrator which includes a control voltage input and capacitors connected in parallel, wherein a top plate of one of the capacitors is connected to a bottom plate of another one of the capacitors for providing a symmetric capacitance, and further wherein the control voltage input comprises a first transistor for receiving a control voltage signal, the first transistor coupled to the power supply and to one end of a resistor, another end of the resistor coupled to both a collector and a base of a second transistor, the second transistor coupled to a plurality of transistors to form a multiple output current mirror, the multiple output current mirror coupled to the capacitors connected in parallel. - View Dependent Claims (10, 11, 12, 13, 14, 18, 19)
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15. A circuit comprising:
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a voltage regulator coupled to a power supply and including a voltage regulator output for providing a regulated voltage, wherein the voltage regulator includes a passive filter coupled to the power supply for attenuating high frequency noise, the passive filter including a first resistor-capacitor pair for attenuating noise frequencies higher than a response ability of the voltage regulator and a second resistor-capacitor pair for attenuating noise frequencies higher than about 800 MHz; and an oscillator, the voltage regulator and the oscillator being implemented on a common substrate, the oscillator coupled to the voltage regulator output, wherein the oscillator comprises a multivibrator which includes a control voltage input and capacitors connected in parallel, wherein a top plate of one of the capacitors is connected to a bottom plate of another one of the capacitors for providing a symmetric capacitance, and wherein the oscillator further comprises a DC bias circuit including a resistor having one end coupled to the voltage regulator output and a second end coupled to a multiple output current mirror, which multiple output current mirror is coupled to the capacitors connected in parallel, for supplying a minimum current to the current mirror for maintaining a minimum oscillation frequency of the multivibrator during an absence of a voltage signal at the control voltage input. - View Dependent Claims (16, 17)
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20. A phase locked loop comprising:
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a regulated power supply; a phase detector including means for receiving a signal; a loop filter coupled to the phase detector for receiving a phase detector output; a VCO coupled to the regulated power supply and to the loop filter for receiving a loop filter output, the VCO providing a voltage controlled output to the phase detector in response to the loop filter output; and a voltage regulator coupled to the regulated power supply and to the VCO for rejecting low frequency noise from the regulated power supply and for providing a noise-attenuated regulated voltage to the VCO; the voltage regulator and the VCO implemented on a common substrate; wherein, the voltage regulator comprises; active filter means for attenuating low frequency noise; a first resistor-capacitor pair for attenuating noise frequencies higher than a response ability of the active filter means; a second resistor-capacitor pair for attenuating noise frequencies higher than about 800 MHz; a band gap circuit; regulator means for providing adequate current to maintain the regulated voltage while preventing noise from passing through the regulator means to the VCO, the regulator means including; a Darlington pair coupled to the regulated power supply, an output of the Darlington pair coupled to the VCO, and a control terminal of the Darlington pair coupled to the band gap circuit for receiving variable current, the band gap circuit coupled to the VCO and controlling the variable current in response to changes in the regulated voltage; further wherein the VCO comprises a multivibrator which includes a control voltage input and capacitors connected in parallel, wherein a top plate of one of the capacitors is connected to a bottom plate of another one of the capacitors for providing a symmetric capacitance, and further wherein the control voltage input comprises a first transistor for receiving a control voltage signal, the first transistor coupled to the power supply and to one end of a resistor, another end of the resistor coupled to both a collector and a base of a second transistor, the second transistor coupled to a plurality of transistors to form a multiple output current mirror, the multiple output current mirror coupled to the capacitors connected in parallel.
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Specification