Abstract: A novel mismatched-shaping DAC architecture is described. The inventive DAC partially spectrally shapes data conversion errors. In accordance with the present invention, the DAC mismatch-shaping function is fully effective for input signal amplitude levels that are relatively low (i.e., close to mid-scale), however, the mismatch-shaping function is not fully effective for input signal amplitude levels that are relatively high. This results in the simplification in complexity, reduced power dissipation, and shortened propagation delays associated with the mismatch-shaping DAC digital logic circuitry. Exemplary delta-sigma ADC and DAC architectures adapted for use with the present inventive partial mismatch-shaping DAC are also described.

Abstract: An integrated circuit capacitor includes a silicon-on-insulator (SOI) substrate and a doped epitaxial layer of a first conductivity type formed on the SOI substrate. The doped epitaxial layer is used as a first plate of the integrated circuit capacitor. A gate oxide layer is formed on the doped epitaxial layer and is used as a dielectric layer of the integrated circuit capacitor. A polysilicon gate is formed on the gate oxide layer and is used as a second plate of the integrated circuit capacitor.

Abstract: A simple, scalable cross-degeneration circuit topology is described. The inventive cross-degeneration method and apparatus provides a circuit design having substantially improved linearity as compared to traditional circuit designs having similar power consumption. The improvement in linearity is achieved without unduly increasing circuit noise and without substantially reducing circuit bandwidth. Using the present inventive method and apparatus, a fixed circuit configuration can be used to accommodate a continuous range of specifications simply by varying component values, in contrast to the prior art requirements of providing additional devices or modifying device wiring. The inventive topology can be implemented using bipolar technologies and conventional MOS processes operating above threshold. Additionally, the inventive circuits can be implemented using other three-terminal (or multi-terminal) amplifying device technologies.

Abstract: This invention relates generally to methods and apparatuses for implementing cyclic return to zero techniques for digital to analog (D/A) conversion. Generally, embodiments of the invention disclose techniques for generating low-distortion continuous-time output waveforms in digital-to-analog converters (DACs) wherein the transient errors are not correlated with the DAC input signal, thereby resulting in DACs with significantly reduced nonlinear distortion. In one embodiment, a cyclic return to zero (CRTZ) digital to analog converter (DAC) includes at least two return to zero (RTZ) signal generating circuits, e.g. RTZ sub-DACs, to perform D/A conversion and a cycler, e.g. an RTZ sub-DAC cycler, to cycle between the two RTZ sub-DACs. The RTZ sub-DAC cycler cycles between the two RTZ sub-DACs such that one of the RTZ sub-DACs is active to perform D/A conversion for at least an entire sample period while the other RTZ sub-DAC is inactive.

Abstract: A novel trench isolated guard ring region for providing RF isolation is disclosed. The semiconductor integrated circuit (IC) device of the present invention comprises a substrate, an insulating layer formed on the substrate, a buried layer formed on the insulating layer, and an epitaxial layer of a first conductivity type formed on the buried layer. A first isolation trench is formed in the epitaxial layer and the buried layer that extends to the insulating layer and that surrounds a first selected surface area of the epitaxial layer. A second isolation trench is formed in the epitaxial layer and the buried layer that extends to the insulating layer and that surrounds the first isolation trench and defines a guard ring region between itself and the first isolation trench. A plurality of isolation chambers is formed within the first and second isolation trenches. A collector is implanted into the epitaxial layer in the guard ring region.

Abstract: An apparatus for receiving signals includes a low noise amplifier (LNA) configured to receive a radio frequency (RF) signal. An I/Q direct down converter is coupled to the LNA. The I/Q direct down converter is configured to split the RF signal into real and imaginary components and to down convert the real and imaginary components directly to baseband signals. A local oscillator (LO) is coupled to the I/Q direct down converter and is configured to drive the I/Q direct down converter. First and second filters are coupled to the I/Q direct down converter. The first and second filters are configured to filter the down converted real and imaginary components, respectively. First and second analog-to-digital converters (ADCs) are coupled to the first and second filters, respectively. The first and second ADCs are configured to convert the real and imaginary components into digital signals.

Abstract: A semiconductor integrated circuit (IC) device includes a substrate, an insulating layer formed on the substrate, a buried layer formed on the insulating layer, and an epitaxial layer of a first conductivity type formed on the buried layer. A first isolation trench is formed in the epitaxial layer and the buried layer that extends to the insulating layer and that surrounds a first selected surface area of the epitaxial layer. A second isolation trench is formed in the epitaxial layer and the buried layer that extends to the insulating layer and that surrounds the first isolation trench and defines a guard ring region between itself and the first isolation trench. A collector is implanted into the epitaxial layer in the guard ring region. A contact is made to the collector, and a conductor connects the contact to a ground node.

Abstract: A method and apparatus for digitally controlling the capacitance of an integrated circuit device using MOS-FET devices. In accordance with one aspect of the present invention, a one-bit or “binary” varactor is presented wherein the gate-to-bulk capacitance of the MOS-FET device exhibits dependency to a D.C. voltage applied between its gate and well implant regions. The capacitance-voltage characteristic of the binary capacitor has three major regions: (1) a first relatively flat region having little or no voltage dependency and having a capacitance equal to a first low capacitance of C1; (2) a sloped region wherein a voltage dependency exists; and (3) a second relatively flat region where there is little or no voltage dependency and where the capacitance equals a second higher capacitance of C2. The capacitance of the binary capacitor can be changed from C1 to C2 simply by changing the polarity of the applied D.C. voltage from a positive to a negative value.

Abstract: An integrated circuit inductor structure that includes a shielding pattern that induces a plurality of small eddy currents to shield the magnetic energy generated by the inductor from the substrate of the IC. The IC inductor structure is formed on a Silicon on Insulator (SOI) substrate where the substrate of the SOI has high resistivity. The shielding pattern forms a checkerboard pattern that includes a plurality of conducting regions completely isolated from each other by oxide material. The inductor has a high quality factor and a high self-resonance frequency due to the effective shielding of electromagnetic energy from the substrate of the IC while not reducing the effective inductance of the inductor.

Abstract: The present invention is a novel method and apparatus for implementing a high-precision timer utilizing a non-optimal oscillator and a high-speed oscillator wherein only one oscillator is enabled at a given moment in time. The high-precision timer method and apparatus comprises a timer and an error-correction technique. In one embodiment, the timer of the present invention is constructed from a high-speed oscillator and a low-speed non-optimal oscillator. The timer operates from the high-speed oscillator during on-the-air modes of operation and from the low-speed non-optimal oscillator during sleep modes of operation. The present inventive method corrects errors that are introduced by the non-optimal oscillator and a swallow counter. The errors are corrected using an error-correction technique having two steps: an error-determination step and an error-correction step.

Abstract: A method and apparatus for digitally controlling the capacitance of an integrated circuit device using MOS-FET devices. In accordance with one aspect of the present invention, a one-bit or “binary” varactor is presented wherein the gate-to-bulk capacitance of the MOS-FET device exhibits dependency to a D.C. voltage applied between its gate and well implant regions. The capacitance-voltage characteristic of the binary capacitor has three major regions: (1) a first relatively flat region having little or no voltage dependency and having a capacitance equal to a first low capacitance of C1; (2) a sloped region wherein a voltage dependency exists; and (3) a second relatively flat region where there is little or no voltage dependency and where the capacitance equals a second higher capacitance of C2. The capacitance of the binary capacitor can be changed from C1 to C2 simply by changing the polarity of the applied D.C. voltage from a positive to a negative value.

Abstract: A crystal oscillator apparatus is described that has a wide dynamic frequency range and that is capable of supporting a broad range of crystal types. The present invention reduces the unwanted side effects that are associated with the prior art crystal oscillator designs, such as the clipping of signals, the introduction of signal distortion and unwanted signal harmonics. The present invention reduces the total wasted loop gain of the oscillator while also reducing the amount of integrated circuit real estate required to implement the crystal oscillator. The crystal oscillator apparatus of the present invention preferably comprises a crystal resonator circuit, an inverting amplifier, a bias circuit, a reference circuit, and a peak detector circuit. The present invention takes advantage of Automatic Gain Control (AGC) design techniques. The gain of the present crystal oscillator is automatically regulated using a closed loop circuit design.

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.

Abstract: A method and apparatus for digitally controlling the capacitance of an integrated circuit device using MOS-FET devices. In accordance with one aspect of the present invention, a one-bit or “binary” varactor is presented wherein the gate-to-bulk capacitance of the MOS-FET device exhibits dependency to a D.C. voltage applied between its gate and well implant regions. The capacitance-voltage characteristic of the binary capacitor has three major regions: (1) a first relatively flat region having little or no voltage dependency and having a capacitance equal to a first low capacitance of C1; (2) a sloped region wherein a voltage dependency exists; and (3) a second relatively flat region where there is little or no voltage dependency and where the capacitance equals a second higher capacitance of C2. The capacitance of the binary capacitor can be changed from C1 to C2 simply by changing the polarity of the applied D.C. voltage from a positive to a negative value.

Abstract: Integrated circuit varactor structures that include either an P-gate/N-well or N-gate/P-well layer configuration formed on an SOI substrate. The varactor structure is completely electrically isolated from the substrate of the IC by an oxide layer of the SOI substrate and by oxide-filled trenches formed on both sides of the varactor structures. The isolation trenches preferably extend to the oxide layer of the SOI substrate. The P-gate/N-well varactor structure includes N+ implant regions formed in an N-well implant layer of the varactor. The N+ implant regions comprise the source and the drain of a varactor. A LOCOS layer may be formed over the N-well layer where the P-gate is formed over the LOCOS layer. The P-gate may be formed of polysilicon. The N-gate/P-well varactor structure includes P+ implant regions formed in a P-well implant layer of the varactor. The P+ implant regions comprise the source and the drain of a varactor.