A voltage-mode transmitter includes a calibration circuit having a replica circuit. By adjusting a feedback voltage driving a gate of a replica transistor in the replica circuit so that an impedance of the replica circuit matches an impedance of a variable resistor, the calibration circuit calibrates an output impedance of a single slice driver.

A clock generation circuit coupled to an integrator circuit uses a variable resistance that is adjusted in a transconductance bias feedback circuit. This resistance is calibrated to the reciprocal of the transconductance of the input amplifier. The product of the adjusted resistance and a capacitance in the clock generation circuit provides a time constant for the settling time of the integrator and controls a pulse width of an adaptively controlled duty cycle output clock.

An apparatus includes circuitry and an oscillator circuit that may be configured to generate a clock signal dependent upon a control signal. The circuitry may be configured to perform a frequency measurement of the clock signal. In response to a determination that the frequency of the clock signal is greater than a first threshold, the circuitry may also be configured to perform a phase comparison between a divided clock signal and a reference clock signal, and to adjust a value of the control signal such that the adjusted value depends upon a result of the comparison. In response to a determination that the frequency of the clock signal is less than the first threshold, the circuitry may be configured to adjust the value of the control signal such that the adjusted value depends upon a result of the measurement.

Performance indicator circuitry is provided for characterizing performance of a phase locked loop (PLL) in a phase path of a polar modulator or polar transmitter that is used to generate a phase modulated RF signal. The PLL includes an oscillator, a high pass path, and a low pass path. The low pass path includes a loop filter. The performance indicator circuitry includes first input circuitry and parameter calculation circuitry. The first input circuitry is configured to input a loop filter signal from the loop filter. The parameter calculation circuitry is configured to compute a value for a performance indicator based on the loop filter signal and control or characterize an aspect of operation of the PLL based on the value.

The invention concerns an apparatus comprising an analog circuit and a digital circuit. The analog circuit may be configured to generate an enable signal in response to (i) a comparison of a width of an up pulse and a pre-determined width and (ii) a comparison of a width of a down pulse and the pre-determined width. The up pulse and the down pulse may be generated in response to a comparison of a feedback signal and a reference signal. The enable signal may be active when both the comparisons are within a pre-determined threshold. The digital circuit may be configured to generate an output signal representing a lock status between (i) the feedback signal and (ii) the reference signal. The lock status may be determined (a) during a decision window based on a number of pulses of the reference signal and (b) when the enable signal is active.

A clock recovery circuit a first phase-locked loop (PLL) circuit configured to perform a coarse phase fixing operation on a test data signal by using a first reference clock signal, the test data signal having a prescribed pattern, and a second PLL circuit configured to perform a fine phase fixing operation on the test data signal, subsequently to the coarse phase fixing operation. The second PLL circuit may be configured to perform the fine phase fixing operation on the test data signal by selectively using at least two selection reference clock signals among a plurality of second reference clock signals that are delayed from the first reference clock signal by a unit phase, in a training mode, having a phase difference of N times the unit phase, where N is an integer equal to or greater than 2.

A voltage-controlled oscillator is provided. A semiconductor device includes a first circuit and a second circuit. The first circuit has a function of holding a first potential and a function of controlling the level of a third potential supplied to the second circuit according to a second potential based on the first potential. The second circuit has a function of outputting a second signal based on a first signal input to the second circuit. The delay time from input of the first signal to the second circuit to output of the second signal from the second circuit is determined by the third potential.

A phase locked loop (PLL) method includes generating a first signal based on a comparison of a phase of a reference clock or signal to a phase of a feedback clock; generating an output clock based on the first signal; generating an intermediate feedback clock including frequency dividing the output clock; fractionally frequency dividing the intermediate feedback clock based on a digital control signal to generate the feedback clock; and generating the digital control signal based on a sampling clock having a frequency greater than a frequency of the feedback clock. In one implementation, a PLL includes a frequency multiplier to generate the sampling clock based on the feedback clock. In another implementation, a PLL uses the intermediate feedback clock as the sampling clock.

An automatic frequency calibration and lock detection circuit includes a frequency error generator circuit, an automatic frequency calibration signal generator circuit, and a lock flag generator circuit. The frequency error generator circuit generates a frequency error signal based on a reference frequency signal and an output frequency signal. The frequency error signal represents a difference between a frequency of the output frequency signal and a target frequency. The automatic frequency calibration signal generator circuit generates an automatic frequency calibration output signal and an automatic frequency calibration done signal based on the frequency error signal and a first clock signal. The lock flag generator circuit generates a lock done signal based on the frequency error signal, the automatic frequency calibration done signal and a second clock signal. The frequency error generator circuit is shared by the automatic frequency calibration signal generator circuit and the lock flag generator circuit.

The present invention relates to a method for generating a reference signal to drive a display apparatus. A method according to the present invention may comprise generating a reference signal having a training pattern being repeated with a periodicity of two clock terms (CTs); and transmitting the reference signal to a phase locked loop (PLL). Each CT has a single embedded clock bit (CB) and a plurality of data bits, and the reference signal has a rising edge at a start point of a first CB corresponding to a first unit interval (UI) of a first CT, and a rising edge at an end point of a second CB corresponding to a first UI of a second CT. According to exemplary embodiments of the present disclosure, energy consumption and EMI effects can be remarkably reduced, and a complexity of PLL can be reduced.