摘要:
A digital-to-analog converter (DAC) for a sigma-delta modulator is provided. The DAC has a switched capacitor structure using an operational amplifier (OP amp) and performs a function exceeding 3-level using a switching method employing only one capacitor in single ended form. Thus, DAC non-linearity caused by capacitor mismatching does not occur, and the number of output levels of the DAC is increased. Also, the DAC capacitor may be applied to a general DAC to increase the ratio of DAC output levels to capacitors.
摘要:
Provided are a dynamic element-matching method, a multi-bit Digital-to-Analog Converter (DAC), and a delta-sigma modulator with the multi-bit DAC and delta-sigma DAC with the multi-bit DAC. The dynamic element-matching method relates to preventing periodic signal components (in-band tones) from being generated from a delta-sigma modulator of a delta-sigma Analog-to-Digital Converter (ADC) and a multi-bit DAC used in a delta-sigma DAC. Unit elements are selected in a new sequence according to a simple algorithm every time that each of unit elements is selected once, and thus the unit elements are not periodically used. Consequently, it is possible to prevent in-band tones caused by a conventional Data Weighted Averaging (DWA) algorithm.
摘要:
A digital-to-analog converter (DAC) for a sigma-delta modulator is provided. The DAC has a switched capacitor structure using an operational amplifier (OP amp) and performs a function exceeding 3-level using a switching method employing only one capacitor in single ended form. Thus, DAC non-linearity caused by capacitor mismatching does not occur, and the number of output levels of the DAC is increased. Also, the DAC capacitor may be applied to a general DAC to increase the ratio of DAC output levels to capacitors.
摘要:
Provided are a dynamic element-matching method, a multi-bit Digital-to-Analog Converter (DAC), and a delta-sigma modulator with the multi-bit DAC and delta-sigma DAC with the multi-bit DAC. The dynamic element-matching method relates to preventing periodic signal components (in-band tones) from being generated from a delta-sigma modulator of a delta-sigma Analog-to-Digital Converter (ADC) and a multi-bit DAC used in a delta-sigma DAC. Unit elements are selected in a new sequence according to a simple algorithm every time that each of unit elements is selected once, and thus the unit elements are not periodically used. Consequently, it is possible to prevent in-band tones caused by a conventional Data Weighted Averaging (DWA) algorithm.
摘要:
Provided is a low-reference-current generator that includes a circuit employing two feedback loops enabling it to operate even at a low voltage, has a high power supply rejection ratio (PSRR) to control power supply noise, and simply forms a voltage without a voltage-to-current converter used in a conventional general reference current generator. The reference current generator includes: a first voltage generator receiving a predetermined current and generating a first voltage that decreases as temperature increases; a second voltage generator generating a second voltage that increases as temperature increases; a first current generator generating a first current corresponding to the first voltage; a second current generator generating a second current corresponding to the second voltage; and a reference current generator receiving the first current and the second current and generating a reference current that is the sum of the first current and the second current.
摘要:
Provided is a clock generator employed in a continuous-time sigma-delta modulator. The clock generator includes an oscillator configured to generate pulses in response to an enable signal, a counter configured to count the number of pulses generated by the oscillator and output the total pulse count, and an output circuit configured to output an inactivated output signal if the pulse count of the counter is equal to a pulse-width control bit. The oscillator includes an astable multi-vibrator. Since the astable multi-vibrator capable of generating a low-jitter pulse from a jittered clock is used as the oscillator, a signal-to-noise ratio is improved. A simple configuration using only digital circuits makes it easier to design a circuit and adjust pulse width. Moreover, according to the structure of the astable multi-vibrator, it is possible to design a circuit to optimally modulate pulse width in connection with process variations of resistors and capacitors used in the continuous-time sigma-delta modulator.
摘要:
Provided are an active resistance-capacitance (RC) integrator and a continuous-time sigma-delta modulator, which have a gain control function. The active RC integrator includes an amplifier, a first base resistor connected between a first input node and a positive input port of the amplifier, a second base resistor connected between a second input node and a negative input port of the amplifier, a first resistor unit connected between the second input node and the positive input port of the amplifier, and a second resistor unit connected between the first input node and the negative input port of the amplifier. A resistor network including resistors and switches is configured to vary an input resistance, so that an active RC integrator may have a gain control function.
摘要:
Provided is a clock generator employed in a continuous-time sigma-delta modulator. The clock generator includes an oscillator configured to generate pulses in response to an enable signal, a counter configured to count the number of pulses generated by the oscillator and output the total pulse count, and an output circuit configured to output an inactivated output signal if the pulse count of the counter is equal to a pulse-width control bit. The oscillator includes an astable multi-vibrator. Since the astable multi-vibrator capable of generating a low-jitter pulse from a jittered clock is used as the oscillator, a signal-to-noise ratio is improved. A simple configuration using only digital circuits makes it easier to design a circuit and adjust pulse width. Moreover, according to the structure of the astable multi-vibrator, it is possible to design a circuit to optimally modulate pulse width in connection with process variations of resistors and capacitors used in the continuous-time sigma-delta modulator.
摘要:
Provided is a digital-to-analog converter converting a digital signal into an analog signal. The digital-to-analog converter includes a decoder for selecting a current source from digital inputs, a current switch driver for driving a current switch of the current source, and a random selection switch disposed between the decoder and the current switch driver, and randomly resetting a connection relationship between outputs of the decoder and inputs of the current switch driver every clock. According to the present invention, the linearity of the digital-to-analog converter may be enhanced by changing the current source selected every clock signal to compensate for non-linearity of the digital-to-analog converter according to the spatial arrangement of the current sources.
摘要:
Provided is a high-speed asynchronous digital signal level conversion circuit converting an input signal of a first voltage level into a signal of a second voltage level. The conversion circuit is able to operate at high speed by connecting first and second nodes, at which the input signal of the first voltage level is converted to the signal of the second voltage level, to a second power source voltage of the second voltage level for fast voltage level conversion when the voltage level of the input signal is changed.