US 6,268,778 B1 · Method and apparatus for fully integrating a voltage controlled oscillator on an integrated circuit

Abstract

A method and apparatus for fully integrating a Voltage Controlled Oscillator (VCO) on an integrated circuit. The VCO is implemented using a differential-mode circuit design. The differential-mode implementation of the VCO preferably comprises a differential mode LC-resonator circuit, a digital capacitor, a differential pair amplifier, and a current source. The LC-resonator circuit includes at least one tuning varactor and two high Q inductors. The tuning varactor preferably has a wide tuning capacitance range. The tuning varactor is only used to “fine-tune” the center output frequency f0 of the VCO. The center output frequency f0 is coarsely tuned by the digital capacitor. The VCO high Q inductors comprise high gain, high self-resonance, and low loss IC inductors. The IC VCO is fabricated on a high resistivity substrate material using a trench isolated guard ring. The guard ring isolates the fully integrated VCO, and each of its component parts, from RF signals that may be introduced into the IC substrate by other devices. By virtue of the improved performance characteristics provided by the digital capacitor, the analog tuning varactor, the high Q inductor, and the trench isolated guard ring techniques, the inventive VCO is fully integrated despite process variations in IC fabrication.

Claims37

Dependent claims

A frequency adjustable oscillator having a variable and selectable oscillation frequency, the oscillator comprising:

a) at least one inductor;
b) a plurality of N multiple capacitance level capacitors coupled together in a parallel configuration each multiple capacitance level capacitor having a plurality of steady-state capacitance levels, the N multiple capacitance level capacitors coupled in parallel with the at least one inductor, wherein the multiple capacitance level capacitors are operatively coupled to associated and corresponding N digital control signals;
and
c) at least one variable capacitance level capacitor coupled in parallel with the N multiple capacitance level capacitors, the capacitance level of the at least one variable capacitor responsive to an analog control signal.

1 more element

An integrated circuit, wherein the integrated circuit is coupled to a plurality of N digital control signals and at least one analog control signal, and wherein the plurality of N digital control signals are used to coarsely tune a frequency adjustable oscillator on the integrated circuit, and wherein the at least one analog control signal is used to fine tune the oscillator, the integrated circuit including:

a) at least one inductor;
b) N multiple capacitance level capacitors coupled together in a parallel configuration each multiple capacitance level capacitor having a plurality of steady-state capacitance levels, wherein the N multiple capacitance level capacitors are also coupled in parallel with the at least one inductor, and wherein the multiple capacitance level capacitors are coupled to respective and corresponding N digital control signals, in a one to one relationship;
and
c) at least one variable capacitance level capacitor coupled in parallel with the N multiple capacitance level capacitors, the capacitance level of the at least one variable capacitor being responsive to at least one analog control signal.

1 more element

Dependencies are inferred from the claim text.

Method and apparatus for fully integrating a voltage controlled oscillator on an integrated circuit

Life of this patent

Method and apparatus for fully integrating a voltage controlled oscillator on an integrated circuit

Life of this patent

Abstract

Claims37