Abstract: A charge-pump phase-locked loop (CP-PLL) circuit with charge calibration. The CP-PLL circuit keeps the phase of an output clock signal constant in a “locked” condition, and includes a charge-pump circuit and a calibration circuit. The charge-pump circuit provides a charge-pump output current. The charge-pump circuit also includes a transistor configured to fine tune the charge-pump output current based on a calibrate voltage signal to eliminate a net charge delivered from the charge-pump output current. The calibration circuit senses the net charge and generates the calibrate voltage signal having a value in proportion to an amount of the net charge. Under control of the calibrate voltage signal, the charge-pump circuit cooperating with the transistor regulates the net charge to become exactly zero, thereby maintaining the phase of the output clock signal locked onto the phase of the reference clock signal.

Abstract: A charge-pump phase-locked loop (CP-PLL) circuit with charge calibration. The CP-PLL circuit keeps the phase of an output clock signal constant in a “locked” condition, and includes a charge-pump circuit and a calibration circuit. The charge-pump circuit provides a charge-pump output current. The charge-pump circuit also includes a transistor configured to fine tune the charge-pump output current based on a calibrate voltage signal to eliminate a net charge delivered from the charge-pump output current. The calibration circuit senses the net charge and generates the calibrate voltage signal having a value in proportion to an amount of the net charge. Under control of the calibrate voltage signal, the charge-pump circuit cooperating with the transistor regulates the net charge to become exactly zero, thereby maintaining the phase of the output clock signal locked onto the phase of the reference clock signal.

Abstract: A charge-pump phase-locked loop (PLL) circuit with charge calibration. The PLL keeps the phase of an output clock signal constant in a “locked” condition, and includes a first charge pump, a second charge pump and a charge sensing circuit. The first and the second charge pumps provide a first current and a second current, respectively. According to a first and second net charge delivered from the first and the second currents separately, the charge sensing circuit provides a calibrate voltage signal as feedback to the first charge pump and the second charge pump. Under control of the calibrate voltage signal, the first and the second charge pumps regulate the first net charge and the second net charge to become exactly zero thereby maintaining the phase of the output clock signal locked onto the phase of a reference clock signal.

Abstract: Invention resides in a switching amplifier having a quaternary input control signal that provides quaternary levels (1, 0H, −1, and 0L) which is coupled to an H-bridge amplifier to provide error cancellation in switching amplifier output signal. The quaternary control signal alternates from a zero state at a high level (“0H”) to a zero state at a low level (“0L”) between each non-zero state (+1 or −1). In a preferred embodiment, a three-level sigma-delta modulator is provided for greater operational efficiency for ease of detecting zero states and minimizing power. The three-level sigma-delta modulator receives and converts an amplifier input signal into a ternary output signal that is then coupled to a ternary-to-quaternary converter to generate the quaternary control signal to provide as input to the H-bridge.

Abstract: Invention resides in a switching amplifier having a quaternary input control signal that provides quaternary levels (1, 0H, −1, and 0L) which is coupled to an H-bridge amplifier to provide error cancellation in switching amplifier output signal. The quaternary control signal alternates from a zero state at a high level (“0H”) to a zero state at a low level (“0L”) between each non-zero state (+1 or −1). In a preferred embodiment, a three-level sigma-delta modulator is provided for greater operational efficiency for ease of detecting zero states and minimizing power. The three-level sigma-delta modulator receives and coverts an amplifier input signal into a ternary output signal that is then coupled to a ternary-to-quaternary converter to generate the quaternary control signal to provide as input to the H-bridge.

Abstract: A conversion system and method is disclosed for converting between digital and analog data signals. The conversion system comprises a signal input line for each digital data signal, a reconstructor-resampler unit for each digital data signal, a combiner, a modulator, a digital-to-analog converter, and a signal output line. Each signal line input couples to the respective reconstructor-resampler unit for the digital data signal. Each reconstructor-resampler unit then couples to a combiner which couples to a modulator. The modulator couples to the digital-to-analog converter that couples to the signal output line from which an analog output signal is produced. The reconstructor-resampler comprises a sampling member coupled to the signal line input and a polynomial interpolator member coupled to the sampling member and the modulator. Also, the modulator operates at a predetermined, or fixed, frequency regardless of the sampling frequency of the digital data signal.

Abstract: In a digital-to-analog converter (DAC) current source including a current mirror, an output transistor biased by a reference voltage and a steering transistor, a structure and a method are provided to implement the DAC current source without current spikes in the output current. Current spikes in the output current are avoided by including a transistor acting as a low-pass filter between the steering transistor and the output transistor. In one embodiment, the DAC current source circuit is implemented by PMOS transistors.

Abstract: A dual sense amplifier structure and a method are provided in a RAMDAC, to allow the video path to be probed digitally during testing. Each of the two sets of sense amplifiers in the dual sense amplifier structure can be individually enabled to provide the same output data to both a color value register accessible over a data port and the digital-to-analog converters for interface with an analog display. In one embodiment, the sense amplifiers which provide color values to a data port interfaced with the CPU are implemented by simpler circuits than the sense amplifiers which used to provide the color values to the DACs.

Abstract: A reference generator system that operates in either a current-controlled mode or a voltage-controlled mode and includes a power-down circuit connected to the operational amplifier to power down the operational amplifier when the reference generator is switched to the current-controlled mode.

Abstract: An amplifier includes an input circuit for alternately selecting input signals to be compared and a first bias circuit for producing self-bias when one of the input signals is selected. A second bias circuit stores the self-bias for use in the amplifier when the other of the input signals is selected for rejecting noise which may accompany power supply voltage applied to the amplifier.

Abstract: A differential amplifier (10) having a circuit (18) which images or simulates the bias current flowing in an input stage (34) of the differential amplifier (10) is disclosed. This image circuit (18) resembles a differential amplifier input stage, couples to the signal inputs (28, 30) of the differential amplifier (10), and provides an output signal that reflects such bias current. One embodiment of the present invention feeds this output signal back to the differential amplifier input stage (34) to improve regulation of a constant current source (26). Another embodiment uses this signal to switch current from an external source (86) to the differential amplifier input stage (34) when a constant current source (26) within the differential amplifier input stage (34) fails to maintain a constant current supply.

Abstract: A data latch with substantially zero hold time and with immunity to input data changes occurring after the latch has slewed toward a definable logic state. An input data flip-flop (10) is coupled via transfer transistors (40, 42) to an output data flip-flop (12). Output nodes (36,38) of the output data flip-flop (12) are prechargeable. Inhibit transistors (24,30) are cross-coupled between the input data flip-flop (10) and the output data flip-flop (12) to prevent input data changes from affecting the latch once the output data flip-flop (12) slews toward a definable stable state.

Abstract: A folded cascode amplifier with rail-to-rail common-mode range utilizes a fully differential input with two sets of input common source amplifier devices to allow rail-to-rail common-mode range. The first set of devices utilizes N-channel transistors (28) and (32) to provide operation in one direction and P-channel transistors (38) and (42) to allow operation in the other direction. Two common gate amplifier output legs are provided for generating a differential voltage between an output node (50) and an output node (48) in a cascode configuration. A feedback circuit is provided for maintaining node (50) at analog ground over the full common-mode range of the input voltage. The feedback circuit utilizes a current source with transistors (88) and (90) and a differentially configured set of transistors (80) and (82) to control a feedback transistor (86).