A High-Efficiency 4x45W Car Audio Power Amplifier using Load Current Sharing

A 4x45W (EIAJ) monolithic car audio power amplifier is presented that achieves a power dissipation decrease of nearly 2x over standard class AB operation by sharing load currents between loudspeakers. Output signals are conditioned using a common-mode control loop to allow switch placement between loads with minimal THD increase. A prototype is realized in a SOI bipolar-CMOS-DMOS process with 0.5μm feature size. Die area is 7.5x4.6mm2. THD+N @(1kHz,10W) is 0.05%

US20040127172A1: Phase-error suppressor and a method of suppressing phase-error

The present invention provides a phase-error suppressor for use with a plurality of transistors having a common source coupled to a current generator that receives signals at a frequency. In one embodiment, the phase-error suppressor includes an inductor, coupled between the common source and the current generator, that resonates proportionally to the frequency with a first capacitance associated with the plurality of transistors. In one embodiment, the inductor resonates at about twice the frequency wherein input phase error is suppressed at output

US20040066241A1: Quadrature voltage controlled oscillator utilizing common-mode inductive coupling

A voltage controlled oscillator including a first oscillator circuit portion with at least one first inductor, and a second oscillator circuit portion with at least one second inductor, wherein the at least one first inductor and the at least one second inductor are electromagnetically coupled to each other

A low-phase-noise 5-GHz CMOS quadrature VCO using superharmonic coupling

A new concept for quadrature coupling of LC oscillators is introduced and demonstrated on a 5-GHz CMOS voltage-controlled oscillator (VCO). It uses the second harmonic of the outputs to couple the oscillators. The technique provides quadrature over a wide tuning range without introducing any increase in phase noise or power consumption. The VCO is tunable between 4.57 and 5.21 GHz and has a phase noise lower than -124 dBc/Hz at 1-MHz offset over the entire tuning range. The worst-case measured image rejection is 33 dB. The circuit draws 8.75 mA from a 2.5-V supply

A low-phase-noise 5GHz quadrature CMOS VCO using common-mode inductive coupling

A new concept for quadrature coupling of LC oscillators is introduced and demonstrated on a 5GHz CMOS VCO. It uses injection-locking through common-mode inductive coupling to enforce quadrature. The technique provides quadrature over a wide tuning range without introducing any phase noise- or power consumption increase. The realized VCO is tunable between 4.6GHz and 5.2GHz and measures a phase noise lower than –124dBc/Hz at 1MHz offset over the entire tuning range. The circuit draws 8.75mA from a 2.5V supply

Frequency dependence on bias current in 5 GHz CMOS VCOs: impact on tuning range and flicker noise upconversion

The tuning curve of an LC-tuned voltage-controlled oscillator (VCO) substantially deviates from the ideal curve 1/√(LC(V)) when a varactor with an abrupt C(V) characteristic is adopted and the full oscillator swing is applied directly across the varactor. The tuning curve becomes strongly dependent on the oscillator bias current. As a result, the practical tuning range is reduced and the upconverted flicker noise of the bias current dominates the 1/f3 close-in phase noise, even if the waveform symmetry has been assured. A first-order estimation of the tuning curve for MOS-varactor-tuned VCOs is provided. Based on this result, a simplified phase-noise model for double cross-coupled VCOs is derived. This model can be easily adapted to cover other LC-tuned oscillator topologies. The theoretical analyses are experimentally validated with a 0.25 μm CMOS fully integrated VCO for 5 GHz wireless LAN receivers. By eliminating the bias current generator in a second oscillator, the close-in phase noise improves by 10 dB and features -70 dBc/Hz at 10 kHz offset. The 1/f2 noise is -132 dBc/Hz at 3 MHz offset. The tuning range spans from 4.6 to 5.7 GHz (21%) and the current consumption is 2.9 mA