Patent ID: 6285214
Filing Date: 2001-09-04
Classification: H03F

Abstract:
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; andat 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; andwherein the at least one control terminal is coupled to the first node for receiving the buffer control signal.