Current controlled oscillator with linear output frequency
First Claim
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1. An oscillator circuit, comprising:
- a plurality of differential amplifier stages serially coupled output to input with a differential output of a last differential amplifier stage cross-coupled to a differential input of a first differential amplifier stage; and
a control circuit having first and second outputs coupled to said plurality of differential amplifier stages for adjusting an output frequency of the oscillator circuit while maintaining linear operation of said output frequency over a control range, said control circuit including,(a) a first differential amplifier having first and second inputs and an output, said first input receiving a first reference signal, said output providing said first output of said control circuit,(b) a first transistor having a gate, a drain and a source, said gate being coupled to said output of said first differential amplifier, said drain being coupled to a first power supply conductor, said source being coupled to said second input of said first differential amplifier, and(c) a second transistor having a gate, a drain and a source, said gate receiving a first control signal, said source being coupled to a second power supply conductor, said drain being coupled to said source of said first transistor.
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Abstract
A current controlled ring oscillator use a plurality of serial amplifier stages with the output of the last stage connected to the input of the first stage. The ring oscillator maintains a linear output frequency over the control range by using a control circuit to compensate for variation in gate-source voltage of output clamping transistors. Moreover, switching nonlinearities can be removed by increasing the minimum value and decreasing the maximum value of the output waveform of each amplifier stage so as to compensate for time lost during the transition of the deadzone.
52 Citations
16 Claims
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1. An oscillator circuit, comprising:
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a plurality of differential amplifier stages serially coupled output to input with a differential output of a last differential amplifier stage cross-coupled to a differential input of a first differential amplifier stage; and a control circuit having first and second outputs coupled to said plurality of differential amplifier stages for adjusting an output frequency of the oscillator circuit while maintaining linear operation of said output frequency over a control range, said control circuit including, (a) a first differential amplifier having first and second inputs and an output, said first input receiving a first reference signal, said output providing said first output of said control circuit, (b) a first transistor having a gate, a drain and a source, said gate being coupled to said output of said first differential amplifier, said drain being coupled to a first power supply conductor, said source being coupled to said second input of said first differential amplifier, and (c) a second transistor having a gate, a drain and a source, said gate receiving a first control signal, said source being coupled to a second power supply conductor, said drain being coupled to said source of said first transistor. - View Dependent Claims (2, 3, 4, 5)
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6. An oscillator circuit, comprising:
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a plurality of differential amplifier stages serially coupled output to input with a differential output of a last differential amplifier stage cross-coupled to a differential input of a first differential amplifier stage, said plurality of differential amplifier stages including first and second control inputs; a first differential amplifier having first and second inputs and an output, said first input receiving a first reference signal, said output being coupled to said first control input of said plurality of differential amplifier stages; a first transistor having a gate, a drain and a source, said gate being coupled to said output of said first differential amplifier, said drain being coupled to a first power supply conductor, said source being coupled to said second input of said first differential amplifier; first current supply means having an output coupled to said source of said first transistor and having a control input coupled for receiving a first control signal; a second differential amplifier having first and second inputs and an output, said first input receiving a second reference signal, said output being coupled to a second control input of said plurality of differential amplifier stages; a second transistor having a gate, a drain and a source, said gate being coupled to said output of said second differential amplifier, said drain being coupled to a second power supply conductor, said source being coupled to said second input of said second differential amplifier; and second current supply means having an output coupled to said source of said second transistor and having a control input coupled for receiving a second control signal. - View Dependent Claims (7, 8, 9, 10, 11)
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12. An integrated oscillator circuit, comprising:
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a plurality of differential amplifier stages serially coupled output to input with a differential output of a last differential amplifier stage cross-coupled to a differential input of a first differential amplifier stage; and a control circuit having first and second outputs coupled to said plurality of differential amplifier stages for adjusting an output frequency of the oscillator circuit while maintaining linear operation of said output frequency over a control range, said control circuit including, (a) a first differential amplifier having first and second inputs and an output, said first input receiving a first reference signal, said output providing said first output of said control circuit, (b) a first transistor having a gate, a drain and a source, said gate being coupled to said output of said first differential amplifier, said drain being coupled to a first power supply conductor, said source being coupled to said second input of said first differential amplifier, and (c) a second transistor having a gate, a drain and a source, said gate receiving a first control signal, said source being coupled to a second power supply conductor, said drain being coupled to said source of said first transistor. - View Dependent Claims (13, 14, 15, 16)
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Specification