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 are a coefficient multiplier and digital delta-sigma modulator using the same. The coefficient multiplier has the average of output signals of respective dependent multipliers as an effective coefficient using a coefficient averaging technique without employing an adder that has a complex structure and occupies a large chip area. Accordingly, the coefficient multiplier has a simple hardware constitution and small chip area in comparison with a canonical signed digit (CSD) coefficient multiplier, and the digital delta-sigma modulator employing the coefficient multiplier has a simple structure and small size.
摘要:
Provided are a gain control device and an amplifier using the gain control device. The gain control device includes a first input resistance unit having a first variable resistor whose resistance is linearly variable and a first fixed resistor respectively receiving a first input signal and a second input signal having a sign different from the first input signal and outputting current through a first output terminal, and a second input resistance unit having a second fixed resistor and a second variable resistor whose resistance is linearly variable respectively receiving the first input signal and the second input signal and outputting current through a second output terminal.Since the gain control device can separately perform dB-linear gain control, it is easily combined with a circuit, such as a continuous-time sigma-delta modulator (SDM), a continuous-time filter, and a continuous-time analog-to-digital converter (ADC), and enables miniaturization and low power consumption.
摘要:
Provided is a read-out circuit that is connected to a microphone and configured to linearly amplify a current signal generated by the microphone and output the amplified current signal. The read-out circuit includes an amplification unit and a feedback resistor. The amplification unit has an amplification gain between 0 and 1. The feedback resistor is connected between input and output terminals of the amplification unit. As the amplification gain of the amplification unit becomes closer to 1, an input impedance becomes higher. A preamp of the read-out circuit can have a high input impedance due to the amplification gain, and the read-out circuit can be manufactured using a CMOS process.
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.