Output buffer stage for use with a current controlled oscillator
AssigneeMotorola, Inc.
InventorEliav Zipper
Life of this patent
Estimating the term…
Abstract
A buffer stage for buffering an input signal generated by a current controlled oscillator comprising: an input terminal that receives the input signal, an output terminal that outputs a buffered signal, at least one buffer, coupled between the input and output terminals that buffers the input signal to generate the buffered signal, the at least one buffer having a current control terminal; and at least one current source having an output coupled to the current control terminal of the at least one buffer, the at least one current source further including at least one control terminal that receives a buffer control signal so that the current output from the current source substantially equals the current sourced by the at least one buffer.
Claims24
A buffer stage for buffering an input signal generated by a current controlled oscillator, the buffer stage comprising:
- an input terminal that receives the input signal;
- an output terminal that outputs a buffered signal;
- at least one buffer, coupled between the input and output terminals, that buffers the input signal to generate the buffered signal, the at least one buffer having a current control terminal;
- and
- at least one adjustable current source having an output coupled to the current control terminal of the at least one buffer, the at least one current source further including at least one control terminal that receives a buffer control signal reflecting the magnitude of the input signal, wherein the current output from the current source substantially equals the current sourced by the at least one buffer;
- wherein the current controlled oscillator comprising of a ring of CMOS inverters and a oscillator current source coupled to each other at a first node;
- wherein an output inverter of the current controlled oscillator provides the input signal;
- wherein the output inverter has a NMOS transistor serially coupled to a PMOS transistor, a source of the PMOS transistor is coupled to the oscillator current source, and a source of the NMOS transistor is coupled to the ground;
- a drain of the NMOS and the PMOS transistors are coupled to each other to form an output terminal of the current controlled oscillator;
- a gate of the PMOS and the NMOS are coupled to form an input terminal of the output inverter;
- and
- wherein the at least one control terminal is coupled to the first node for receiving the buffer control signal.
A buffer stage for buffering an input signal generated by a current controlled oscillator, the buffer stage comprising:
- an input terminal that receives the input signal;
- an output terminal that outputs a buffered signal;
- at least one buffer, coupled between the input and output terminals, that buffers the input signal to generate the buffered signal, the at least one buffer having a current control terminal;
- and
- at least one adjustable current source having an output coupled to the current control terminal of the at least one buffer, the at least one current source further including at least one control terminal that receives a buffer control signal reflecting the magnitude of the input signal, wherein the current output from the adjustable current source is substantially proportional to a square of the peak to peak voltage of the input signal.
A buffer stage for buffering an input signal generated by a current controlled oscillator, the buffer stage comprising:
- an input terminal that receives the input signal;
- an output terminal that outputs a buffered signal;
- at least one buffer, coupled between the input and output terminals, that buffers the input signal to generate the buffered signal, the at least one buffer having a current control terminal;
- and
- at least one adjustable current source having an output coupled to the current control terminal of the at least one buffer, the at least one current source further including at least one control terminal that receives a buffer control signal reflecting the magnitude of the input signal, the at least one adjustable current source emulates the at least one buffer.
A method for buffering an input signal generated by a current controlled oscillator, the method comprising the steps of:
- providing the input signal to an input terminal of a current controlled buffer stage and providing a buffer control signal reflecting a peak to peak voltage of the input signal to a control terminal of an adjustable current source;
- generating a control signal from the buffer control signal, providing the control signal to a control terminal of the buffer stage while the buffer stage generates the buffered signal;
- and
- wherein the control signal equals the current sourced by the buffer stage;
- wherein the step of generating a control signal from the buffer control signal and providing the control signal to a control terminal involves:
- emulating the behavior of a last stage of the current controlled oscillator;
- mirroring a control signal provided during the emulation to the control terminal.
A method for buffering an input signal generated by a current controlled oscillator, the method comprising the steps of:
- providing the input signal to an input terminal of a current controlled buffer stage and providing a buffer control signal reflecting a peak to peak voltage of the input signal to a control terminal of an adjustable current source;
- generating a control signal from the buffer control signal, providing the control signal to a control terminal of the buffer stage while the buffer stage generates the buffered signal;
- and
- wherein the control signal is substantially proportional to a square of the peak to peak voltage of the input signal.
Dependencies are inferred from the claim text.