Abstract: An audio amplifier system may include an audio CODEC/output (AOP) path featuring analog class-D amplifiers, and using Natural Sampling Pulse Width Modulation (PWM) to convert an analog input into a series of Rail-to-Rail pulses. The audio signal may be encoded in the average value of the PWM pulse train and may be recovered from the PWM signal by analog low pass filtering. The Class-D amplifiers may be designed with a negative feedback loop/network to compare the output signal with the input signal and suppress non-idealities introduced by the Class-D switching stage. Furthermore, operation of the AOP may be designed according to a separate signal transfer function and a separate noise transfer function, and 2nd order noise shaping may be performed at low power, with an optimized filter included in the feedback loop to achieve the best noise reduction at low power.

Abstract: An audio amplifier system may include an audio CODEC/output (AOP) path featuring analog class-D amplifiers, and using Natural Sampling Pulse Width Modulation (PWM) to convert an analog input into a series of Rail-to-Rail pulses. The audio signal may be encoded in the average value of the PWM pulse train and may be recovered from the PWM signal by analog low pass filtering. The Class-D amplifiers may be designed with a negative feedback loop/network to compare the output signal with the input signal and suppress non-idealities introduced by the Class-D switching stage. Furthermore, operation of the AOP may be designed according to a separate signal transfer function and a separate noise transfer function, and 2nd order noise shaping may be performed at low power, with an optimized filter included in the feedback loop to achieve the best noise reduction at low power.

Abstract: The present invention relates generally to communications, and more specifically to a method and apparatus for generating local oscillator signals used for up- and down-conversion of RF (radio frequency) signals. A major problem in the design of modulators and demodulators, if the leakage of local oscillator (LO) signals into the received signal path. The invention presents a number of highly integratable circuits which resolve the LO leakage problem, using regenerative divider circuits acting on oscillator signals which are running at a multiple or fraction of the frequency of the desired LO signal, to generate in-phase (I) and quadrature (Q) mixing signals. Embodiments of these circuits also use harmonic subtraction and polyphase mixers, as well as virtual local oscillator TM (VLO) mixing signals. VLO mixing signals are signal pairs which emulate local oscillator signals by means of complementary mono-tonal and multi-tonal mixing signals.

Abstract: An inexpensive, high-performance, fully-integrable, multi-standard transceiver with a topology including: an active mixer, followed by a high pass filter, and a passive mixer. The input signal is modulated up, or demodulated down, using a pair of complementary, aperiodic mixing signals. The use of aperiodic mixing signals allows a fully-integrated transceiver to be built. Embodiments of the active mixer include those having electrically-adjustable performance and allowing multiple RF signal inputs. This allows the topology to be employed in multi-band, multi-frequency applications, while still providing high performance.

Abstract: The present invention relates generally to communications, and more specifically to a method and apparatus for generating local oscillator signals used for up- and down-conversion of RF (radio frequency) signals. A major problem in the design of modulators and demodulators, if the leakage of local oscillator (LO) signals into the received signal path. The invention presents a number of highly integratable circuits which resolve the LO leakage problem, using regenerative divider circuits acting on oscillator signals which are running at a multiple or fraction of the frequency of the desired LO signal, to generate in-phase (I) and quadrature (Q) mixing signals. Embodiments of these circuits also use harmonic subtraction and polyphase mixers, as well as virtual local oscillator TM (VLO) mixing signals. VLO mixing signals are signal pairs which emulate local oscillator signals by means of complementary mono-tonal and multi-tonal mixing signals.

Abstract: The present invention relates generally to communications, and more specifically to a method and apparatus of modulating baseband and RF (radio frequency) signals. A modulator topology is disclosed in which an input signal x(t) is up-converted to an output signal y(t), either by mixing it with two mixing signals ?1 and ?2 (“pseudo-direct conversion” mode), or by mixing it with only one mixing signal ?2 (“direct-conversion” mode). In pseudo-direct modulation mode, the ?1 and ?2 mixing signals emulate a local oscillator signal; the product ?1*?2 has significant power at the frequency of a local oscillator signal being emulated, but neither ?1 nor ?2 have significant power at the frequency of the input signal x(t), the LO signal being emulated, or the output signal ?1 ?2 x(t).

Abstract: There is a need for an inexpensive, high-performance, fully-integrable, multi-standard transceiver. The invention provides a topology that satisfies this need, consisting of: an active mixer, followed by a high pass filter, and a passive mixer. The input signal is modulated up, or demodulated down, using a pair of complementary, aperiodic mixing signals. The use of aperiodic mixing signals allows a fully-integrated transceiver to be built. Several embodiments of the active mixer are also presented, including those having electrically-adjustable performance and allowing multiple RF signal inputs. This allows the topology of the invention to be employed in multi-band, multi-frequency applications, while still providing high performance.

Abstract: A conventional differential transistor pair is provided with a dynamic bias circuit. The input voltage signal for the differential pair is also full-wave rectified and the rectified signal is used to bias dynamically the differential pair while the input voltage signal is being applied. One or more bias transistors having a control electrode fed with the rectified signal is connected in series with the differential pair. The result is that as the input signal magnitude increases the amount of bias increases dynamically and increases linearly for larger signals. Desired responses other than linearity can be achieved by making the signal that is fed to the rectifier vary according to any predetermined function.

Abstract: A conventional differential transistor pair is provided with a dynamic bias circuit. The input voltage signal for the differential pair is also full-wave rectified and the rectified signal is used to bias dynamically the differential pair while the input voltage signal is being applied. One or more bias transistors having a control electrode fed with the rectified signal is connected in series with the differential pair. The result is that as the input signal magnitude increases the amount of bias increases dynamically and increases linearly for larger signals. Desired responses other than linearity can be achieved by making the signal that is fed to the rectifier vary according to any predetermined function.

Abstract: The present invention deals with the problems related to thermal runaway and over-voltage breakdown in integrated circuits using a series of power transistors interconnected in a parallel circuit arrangement. The general technique described consists of a protection scheme that involves the application of a fusible material to form ballast resistor components. These components are connected in series with each of the transistors in the integrated circuits. The main advantages are significant area and cost savings in the manufacturing of the integrated circuits as well as an increase in their yield, thereby reducing costly field maintenance and equipment returns.

Abstract: A conventional differential transistor pair is provided with a dynamic bias circuit. The input voltage signal for the differential pair is also full-wave rectified and the rectified signal is used to bias dynamically the differential pair while the input voltage signal is being applied. One or more bias transistors having a control electrode fed with the rectified signal is connected in series with the differential pair. The result is that as the input signal magnitude increases the amount of bias increases dynamically and increases linearly for larger signals. Desired responses other than linearity can be achieved by making the signal that is fed to the rectifier vary according to any predetermined function.

Abstract: In a tree mixer having an input differential pair of transistors as a gain stage and two differential pairs of transistors (transistor quad) as a mixing stage, a further transistor quad in the mixing stage is provided. The further transistor quad is complementary with respect to the first transistor quad. A DC offset is applied between respective mixing inputs of the two transistor quads and the local oscillator input signal is applied to both inputs. The two transistor quads are interconnected through summing circuits such as current mirrors. By appropriately setting the DC offset the mixer can be operated in class A, B or AB as desired.

Abstract: A gate controlled lateral bipolar junction transistor (GCLBJT) device for an integrated circuit and a method of fabrication thereof are provided. The GCLBJT resembles a merged field effect transistor and lateral bipolar transistor, i.e. a lateral bipolar transistor having base, emitter and collector terminals and a fourth terminal for controlling a gate electrode overlying an active base region. The device is operable as an electronically configurable lateral transistor. Advantageously a heavily doped buried layer provides a base electrode having a base contact which surrounds and encloses the collector. The surface region between emitter and collector is characterized by lightly doped regions adjacent and contiguous with the heavily doped emitter and collector, which effectively reduce the base width of the bipolar transistor and improve operation for analog applications.