摘要:
A clock generating apparatus and a fractional frequency divider thereof are provided. The fractional frequency divider includes a frequency divider (FD), a plurality of samplers, a selector and a control circuit. An input terminal of the FD is coupled to an output terminal of a multi-phase-frequency generating circuit. Input terminals of the samplers are coupled to an output terminal of the FD. Trigger terminals of the samplers receive the sampling clock signals. The input terminals of the selector are coupled to output terminals of the samplers. An output terminal of the selector is coupled to a feedback terminal of the multi-phase-frequency generating circuit. The control circuit provides a fraction code to a control terminal of the selector, so as to control the selector for selectively coupling the output terminal of one of the samplers to the feedback terminal of the multi-phase-frequency generating circuit.
摘要:
A triangular wave generator, comprising: a first frequency divider, for utilizing a first positive integer to divide a first frequency of a first periodical signal to generate a first frequency-divided signal; a second frequency divider, for utilizing a second positive integer to divide a second frequency, which equals the first frequency multiplying a third positive integer, of a second periodical signal to generate a second frequency-divided signal; and an up/down counter, for generating a triangular wave first and second frequency-divided frequencies respectively belonging to first and second frequency divided signals; wherein a frequency of the triangular wave equals to the first frequency-divided frequency, and an amplitude of the triangular wave is determined according to a ratio of the first and second frequency-divided frequencies.
摘要:
Over-voltage indicator and related circuit and method. The over-voltage indicator can work with an I/O circuit of a chip for detecting over-voltage in an I/O pad and providing an indication signal accordingly. When over-voltage does not happen, the over-voltage indicator continues to detect a signal level of the I/O pad and keeps the indication signal low. Once over-voltage is detected, the over-voltage indicator pauses detecting, asserts a high level in the indication signal, and periodically resumes detecting until end of over-voltage is detected. With informing provided by the indication signal, a core cell of the chip can perform proper operation to reduce potential damage caused by over-voltage.
摘要:
A signal detection circuit is used for detecting signal squelch of a differential input signal to generate a corresponding digital output signal. The signal detection circuit includes: a reference voltage generator for generating a reference voltage of which the common mode voltage tracks the common mode voltage of the input signal; a real-time signal judgment circuit, real-time rectifying and amplifying a difference between the input signal and the reference voltage; and a deglitch circuit, sampling and/or amplifying an output signal of the real-time signal judgment circuit, and transforming sampling results into the digital output signal to reflect signal squelch of the differential input signal.
摘要:
Over-voltage indicator and related circuit and method. The over-voltage indicator can work with an I/O circuit of a chip for detecting over-voltage in an I/O pad and providing an indication signal accordingly. When over-voltage does not happen, the over-voltage indicator continues to detect a signal level of the I/O pad and keeps the indication signal low. Once over-voltage is detected, the over-voltage indicator pauses detecting, asserts a high level in the indication signal, and periodically resumes detecting until end of over-voltage is detected. With informing provided by the indication signal, a core cell of the chip can perform proper operation to reduce potential damage caused by over-voltage.
摘要:
A frequency detection circuit and a detection method thereof suitable for a clock data recovery (CDR) circuit are provided. The frequency detection circuit includes a phase detector, a first delayer, a frequency detector, and a logic circuit. The phase detector samples a data signal according to a first clock signal provided by the CDR circuit and provides a phase instruction signal according to the sampling. The first delayer delays the first clock signal to obtain a second clock signal. The frequency detector samples the data signal according to the second clock signal and provides a frequency instruction signal according to the sampling. The logic circuit generates a clock instruction signal according to the phase instruction signal and the frequency instruction signal. The CDR circuit adjusts the frequency of the first clock signal according to the status of the clock instruction signal.
摘要:
A signal comparison circuit is provided. The signal comparison circuit includes a first amplifier, a second amplifier, a peak detector, and a comparator. The first amplifier is a zero-peaking amplifier. The first amplifier receives and amplifies a data signal. The second amplifier receives and amplifies a reference voltage. The peak detector is coupled to the first and the second amplifiers for detecting and maintaining maximum values of the amplified data signal and the amplified reference voltage, and then outputting the maintained data signal and the maintained reference voltage. The comparator is coupled to the peak detector for comparing the maintained data signal with the maintained reference voltage and outputting a result of the comparison.
摘要:
A signal detection circuit is used for detecting signal squelch of a differential input signal to generate a corresponding digital output signal. The signal detection circuit includes: a reference voltage generator for generating a reference voltage of which the common mode voltage tracks the common mode voltage of the input signal; a real-time signal judgment circuit, real-time rectifying and amplifying a difference between the input signal and the reference voltage; and a deglitch circuit, sampling and/or amplifying an output signal of the real-time signal judgment circuit, and transforming sampling results into the digital output signal to reflect signal squelch of the differential input signal.
摘要:
A signal comparison circuit is provided. The signal comparison circuit includes a first amplifier, a second amplifier, a peak detector, and a comparator. The first amplifier is a zero-peaking amplifier. The first amplifier receives and amplifies a data signal. The second amplifier receives and amplifies a reference voltage. The peak detector is coupled to the first and the second amplifiers for detecting and maintaining maximum values of the amplified data signal and the amplified reference voltage, and then outputting the maintained data signal and the maintained reference voltage. The comparator is coupled to the peak detector for comparing the maintained data signal with the maintained reference voltage and outputting a result of the comparison.
摘要:
A frequency detection circuit and a detection method thereof suitable for a clock data recovery (CDR) circuit are provided. The frequency detection circuit includes a phase detector, a first delayer, a frequency detector, and a logic circuit. The phase detector samples a data signal according to a first clock signal provided by the CDR circuit and provides a phase instruction signal according to the sampling. The first delayer delays the first clock signal to obtain a second clock signal. The frequency detector samples the data signal according to the second clock signal and provides a frequency instruction signal according to the sampling. The logic circuit generates a clock instruction signal according to the phase instruction signal and the frequency instruction signal. The CDR circuit adjusts the frequency of the first clock signal according to the status of the clock instruction signal.