Abstract: In an example method, a vehicle configured to operate in an autonomous mode could have a radar system used to aid in vehicle guidance. The method could include transmitting at least two signal pulses. The method further includes, for each transmitted signal pulse, receiving a reflection signal associated with reflection of the respective transmitted signal pulse. Each reflection signal may be received when the apparatus is in a different respective location. Additionally, the method includes processing the received reflection signals to determine target information relating to one or more targets in an environment of the vehicle. Also, the method includes correlating the target information with at least one object of a predetermined map of the environment of the vehicle to provide correlated target information. Yet further, the method includes storing the correlated target information for the at least one object in an electronic database.

Abstract: Representative implementations of devices and techniques provide bipolar time-to-digital conversion. For example, either a positive time duration or a negative time duration may be converted to a digital representation by a linear time-to-digital converter (TDC). A set of logic functions may be applied to the input of the TDC to provide start and/or stop signals for the TDC. Further, a correction component may be applied to an input or an output of the TDC to compensate for a delay offset of the TDC.

Abstract: In one example, there is disclosed a hybrid analog-digital point-of-load controller (ADPOL) for use in a power supply. The ADPOL is configured to respond to transient current loads. In the presence of moderate current transients, power is clocked by a digital power core, which may be programmatically configured to adjust pulse width in response to the transient. In the presence of larger current transients, control may be passed to an analog transient compensator, which includes high-speed circuitry selecting between a very high-duty-cycle clock and a very low-duty-cycle clock, which will drive the transient back to the digital control domain.

Abstract: A duty cycle error accumulation circuit includes first to nth delay units and a feedback unit. The first to nth delay units receive a clock signal, a first input signal and a second input signal, respectively, to generate a first output signal and a second output signal by delaying one signal selected from first and second input signals based on a logic level of the clock signal. The feedback unit supplies second input signal to a kth delay unit based on second output signal of a (k+1)th delay unit. The first output signal of the kth delay unit is supplied to the (k+1)th delay unit as first input signal, and the clock signal is supplied to the first delay unit as first input signal and to the nth delay unit as second input signal. The duty cycle error accumulation circuit effectively corrects a duty cycle of a clock signal.

Abstract: Systems and methods are disclosed including a duty cycle module having two timer circuits to measure pulse widths of a clock signal. Two comparators are used to generate control signals depending upon comparisons of the pulse width measurements. In response to the control signals, either the clock signal or an inverted clock signal may be programmably delayed such that combination of the clock signal and the inverted clock signal results in a corrected clock signal. Systems and methods are also disclosed for verifying operation of a duty cycle module.

Abstract: One embodiment provides a system for generating a reference waveform. The system can include a first pulse-width modulation (PWM) channel configured to provide a first PWM waveform having a first duty cycle and a first frequency. A second PWM channel is configured to provide a second PWM waveform having a second duty cycle and the first frequency. Combinational logic is configured to combine the first PWM waveform and the second PWM waveform to generate a phase-shifted reference PWM waveform having the first frequency and a phase shift that is based on the first duty cycle and the second duty cycle.

Abstract: A voltage scaling circuit includes a first critical path and an edge detection unit. The first critical path includes an input and an output. The edge detection unit includes a first input, a second input, a counter and a time-to-digital converter (TDC). The input of the first critical path is electrically connected to the first input of the edge detection unit, and the output of the critical path is electrically connected to the second input of the edge detection unit. The counter is configured to measure a duration between an active edge of a start signal on the first input of the edge detection unit and an active edge of a stop signal on the second input of the edge detection unit in a clock period basis. The TDC is configured to measure a beginning portion and an end portion of the duration.

Abstract: The duty ratio of a PWM signal is prevented from being zero immediately after the start of PWM control, for example. A PWM limiter circuit has a structure with which a signal output from the PWM limiter circuit can be prevented from being higher than a certain value or lower than a certain value. The PWM limiter circuit includes a comparator circuit, a controller circuit, and a switch circuit. The highest duty ratio reference voltage VrefH is input to a first input terminal. The lowest duty ratio reference voltage VrefL is input to a second input terminal. Voltage Verr output from an error amplifier is input to a third input terminal.

Abstract: A duty cycle correction circuit includes: a duty cycle correction unit configured to correct a duty cycle of an input clock signal according to a duty cycle correction code and generate an output clock signal; a duty cycle detection section configured to detect a duty cycle of the output clock signal and generate an up-down signal; a noise detection signal generation section configured to detect a variation of the up-down signal and generate the noise detection signal; and a duty cycle correction control unit configured to generate the duty cycle correction code in response to the noise detection signal and the up-down signal.

Abstract: Duty cycle based phase interpolators, and methods for implementing duty cycle based phase interpolators are disclosed. One such phase interpolator includes a first pulse width modulator configured to generate a first duty cycle signal, and a second pulse width modulator configured to generate a second duty cycle signal. The phase interpolator further includes a logic unit configured to merge the first duty cycle signal and the second duty cycle signal to produce a periodic digital signal with a controllable phase depending on the first and second duty cycle signals.

Abstract: A noise discriminator circuit and a noise discrimination method in a burst mode receiver is configured to determine the validity of an incoming burst signal by analyzing the timing of the signal edges of incoming signal to look for a time duration conforming to the preamble data bits of a valid burst signal. In one embodiment, the noise discriminator circuit and method analyze the time duration between signal edges of the same pulse of an incoming signal. In another embodiment, the noise discriminator circuit and method analyze the time duration between a first set of pulses of an incoming signal and the time duration between signal edges of a second set of pulses of the incoming signal. When the time durations are within a given time range relating to a predetermined timing separation of a valid burst signal, the incoming signal is validated as a valid burst signal.

Abstract: A controller for controlling an LED assembly is described. The controller is arranged to—receive an input signal representing a required characteristic of the LED assembly,—convert the input signal to a control signal for the LED assembly,—apply a correction to the control signal to obtain a corrected control signal, the correction being based on a predetermined transient characteristic of the LED assembly,—output the corrected control signal. As such, a better correspondence between a required characteristic and an actual characteristic of the LED assembly is obtained.

Abstract: Described herein are an apparatus, system, and method for compensating voltage swing and duty cycle of a signal on an input-output (I/O) pad of a processor by adjusting the voltage swing and duty cycle of the signal. The apparatus comprises a driver to transmit a signal on an I/O pad, the signal on the I/O pad having a voltage swing and a duty cycle; and an adjustment unit, coupled to the driver, to receive the signal from the I/O pad transmitted by the driver and to generate voltage swing and duty cycle control signals for adjusting the voltage swing and duty cycle of the signal on the I/O pad respectively. Described herein is also an analog-to-digital (A2D) converter for measuring and/or calibrating various signal attributes including current, voltage, and time.

Abstract: Duty cycle based phase interpolators, and methods for implementing duty cycle based phase interpolators are disclosed. One such phase interpolator includes a first pulse width modulator configured to generate a first duty cycle signal, and a second pulse width modulator configured to generate a second duty cycle signal. The phase interpolator further includes a logic unit configured to merge the first duty cycle signal and the second duty cycle signal to produce a periodic digital signal with a controllable phase depending on the first and second duty cycle signals.

Abstract: An output stage configured to control a driving voltage thereof is provided. The output stage includes: a first switching current module, coupled to a node for outputting a first current; a second switching current module, coupled to the node for outputting a second current; a switching capacitor module with a capacitance, coupled to the node; a calibrating control circuit, for calibrating the first current, the second current and the capacitance; a time constant calibrating circuit, for generating a reference slew rate, and controlling the calibrating control circuit to selectively calibrate the first current, the second current and the capacitance, such that a ratio of the first current and the capacitance and the ratio of the second current and the capacitance conform to the reference slew rate; and a voltage clamper for setting a high/low voltage range and limiting a amplitude of the driving voltage within the high/low voltage range.

Abstract: A semiconductor device includes a first duty determining circuit (20) and a second duty determining circuit (30). The first duty determining circuit (20) determines a duty correction condition for an input signal in a first predetermined cycle longer than a cycle of the input signal to obtain a first determination result and updates the duty correction condition for the input signal on the basis of the first determination result. The second duty determining circuit (30) determines the duty correction condition for the input signal in a second predetermined cycle shorter than first predetermined cycle to obtain a second determination result and updates the duty correction condition for the input signal only when the second determination result is fixed during a predetermined period.

Abstract: The duty ratio of a PWM signal is prevented from being zero immediately after the start of PWM control, for example. A PWM limiter circuit has a structure with which a signal output from the PWM limiter circuit can be prevented from being higher than a certain value or lower than a certain value. The PWM limiter circuit includes a comparator circuit, a controller circuit, and a switch circuit. The highest duty ratio reference voltage VrefH is input to a first input terminal. The lowest duty ratio reference voltage VrefL is input to a second input terminal. Voltage Verr output from an error amplifier is input to a third input terminal.

Abstract: A method and apparatus to implement clock signal adaptation is provided to characterize an input clock signal that is to be adapted and in response, generate adaptation updates at each subsequent clock cycle of the input clock signal. In a first embodiment, clock signal adaptation occurs through duty cycle correction (DCC) to substantially achieve a 50% duty cycle. In an alternate embodiment, clock signal adaptation occurs through a multiplication operation that is applied to the clock signal to be adapted, whereby the multiplication operation is parameterizable to allow odd/even multiplication. In an alternate embodiment, clock signal adaptation occurs through a phase-shift operation that is applied to the clock signal to be adapted, whereby the phase-shift operation is parameterizable to allow all possible fractions and percentages of phase shifts.

Abstract: A data output strobe signal generating circuit includes a duty cycle correcting unit that corrects the duty ratio of an input clock in response to a control signal to generate a corrected clock. A data output strobe signal generating unit receives the corrected clock and generates a data output strobe signal. A duty cycle control unit receives the data output strobe signal and outputs the control signal.

Abstract: A pulse controller with dual latches includes a first latch unit and a second latch unit, in which two latch units are used to latch signal level for ensuring a sufficient conducting amount of the switching element in the rear end power output unit, and through a mutual interaction between the first and the second latch units, a complementary turning-on and turning-off situation therebetween is formed, and further, the signal from a trigger signal source and the feedback from the power output unit are employed to generate the duty cycle signal for the power output unit so as to replace the conventional pulse width modulation circuit.

Abstract: Signal phase adjustment for duty cycle control is described. A first sample clock signal and a second sample clock signal are provided. A first phase signal and a second phase signal are generated responsive to the first sample clock signal, where the first phase signal is out of phase with respect to the second phase signal. The second sample clock signal configured to be swept in phase in relation to the first phase signal. A combined signal is generated where the combined signal has a duty cycle associated with the first phase signal and the second phase signal in combination. A first counter and a second counter are clocked responsive to the second sample clock signal to count. A first count from the first counter is divided by a second count from the second counter to obtain the duty cycle associated with the combined signal.

Abstract: A circuit drives an LED array and controls the brightness of the LED array by regulating the current flowing through the array. The LED array is driven by a pulse-shaped current of which the mean value is regulated with at least one or two of the following types of modulation: frequency modulation, pulse-width modulation, and amplitude modulation.

Abstract: In one embodiment, a method for a control interface includes: receiving a signal conveying bits of information over a single line; and for each bit of information, comparing the proportion of time that the signal on the single line is low versus the proportion of time that the signal on the single line is high for a respective bit period defined from one operative edge of the signal to the next operative edge of the signal in order to determine a logic value for that bit of information.

Abstract: The disclosed methodology and apparatus measures the duty cycle of a reference clock signal that a clock circuit supplies to a duty cycle measurement (DCM) circuit located “on-chip”, namely on an integrated circuit (IC) in which the DCM circuit is incorporated. In one embodiment, the DCM circuit includes a capacitor driven by a charge pump. The reference clock signal drives the charge pump. The clock circuit varies the duty cycle of the reference clock signal among a number of known duty cycle values. The DCM circuit stores resultant capacitor voltage values corresponding to each of the known duty cycle values in a data store. The DCM circuit applies a test clock signal having an unknown duty cycle to the capacitor via the charge pump, thus charging the capacitor to a new voltage value that corresponds to the duty cycle of the test clock signal. Control software accesses the data store to determine the duty cycle to which the test clock signal corresponds.

Abstract: A duty cycle correction circuit comprises a tuned circuit, a delay circuit and a phase-locked loop; wherein the tuned circuit receives an input clock, generates a periodic pulse according to the input clock, tunes the periodic pulse depending on a reference voltage, and outputs an output clock; a delay circuit receives the output clock, and generates a complementary signal; a phase lock loop receives the complementary signal, measures the periods of time of the high level state and the low level state of the complementary signal, generates the reference voltage and feeds back to the tuned circuit. By using the technique of the present invention, it is able to track the delay time between the input clock and the output clock, and the drift of the output clock is reduced.

Abstract: A deglitch circuit utilizes a first flip-flop coupled to the input signal and a second flip-flop coupled to the output of a circuit with feedback from the output to gates to control first and second inputs to the first flip-flop. In an alternative arrangement, a counter is provided between the output of the first flip-flop and the input to the second flip-flop in order to provide flexibility and the possibility of a longer delay for the circuit.

Abstract: A serial interface circuit for a single logic input pin of an electronic system, comprising a decoder for converting a pulse width modulated input signal applied to the pin to a sequence of logic low and logic high values. The decoder comprises an up/down counter with a count input connected to a clock source, an edge detection circuit detecting rising and falling edges of the input signal. The edge detection circuit is connected to the up/down counter to start up counting from a reset value upon detection of an edge in a first direction and to start down counting from a current count upon detection of an edge in a second direction. The decoder further comprises a bit value deciding circuit that delivers a first logic value when the count of the up/down counter is above the reset value on detection of an edge in the second direction and delivers a second logic value when the count of the up/down counter is at or below the reset value on detection of an edge in the second direction.

Abstract: A pulse width modulation (PWM) controlling module, includes: a PWM controller, a load detector, and an adjusting module. The PWM controller generates a PWM signal that is utilized for controlling a supply voltage applied to an electronic system. The load detector, coupled to the PWM controller, detects a load of the electronic system according to the PWM signal and generates a decision value accordingly. The adjusting module, coupled to the PWM controller and the load detector, controls the PWM controller to adjust the PWM signal according to the decision value.

Abstract: Systems and methods are disclosed for minimizing nth-order harmonic associated with a square wave clock signal having a predetermined frequency and duty cycle. The system changes the duty cycle of the clock to eliminate or suppress the nth-order harmonic of the clock; and generates a low-interference clock having the changed duty cycle while keeping the predetermined frequency.

Abstract: Systems and methods are disclosed for minimizing nth-order harmonic associated with a square wave clock signal having a predetermined frequency and a duty cycle. The system changes the duty cycle of the clock to eliminate or suppress the nth-order harmonic of the clock; and generates a low-interference clock having the changed duty cycle while keeping the predetermined frequency.

Abstract: A voltage conversion circuit has a pulse generator that generates a pulse signal having a fixed pulse width and a variable pulse period. The output voltage of this voltage conversion circuit is determined according to the ratio of the pulse width to the pulse period of the pulse signal generated by the pulse generator. This circuit configuration makes it possible to produce as the output voltage lower voltages than ever.

Abstract: Clock recovery from transmitted data signals is carried out entirely digitally, and in a manner that is essentially insensitive to dynamic changes in the phase of the data signal. To this end, at least four phase-shifted sample signals are produced from a predetermined time signal. At least two of these phase-shifted sample signals are selected as a function of the respective phase angles with respect to the data signal, and in each case are supplied separately to a device for time sampling of the data signal with the selected sample signal. One of the devices in each case is connected to an output device for the data signal as a function of the respective phase separations between the data signal and the selected phase-shifted sample signals.

Abstract: A circuit, system, and method is provided for regulating the pulse width and/or duty cycle of a signal indirectly or directly used to drive, e.g., a transmitter. The load of the transmitter can be, for example, an optical signal transmitter. The circuit includes a feedback loop that adjusts the output signal so that the lower voltages are chopped at a reference voltage input into the driver. The magnitude of the reference voltage will regulate the pulse width of the output signal, as well as the duty cycle of the output signal. A low input voltage swing is well-suited to be operated upon by the driver circuit to produce a symmetric pulse width that is particularly adapted to high-speed optical data communication applications. The gain and slew rate of the feedback circuit and, predominantly, the comparator and pull-down transistor of the feedback circuit is tuned to ensure the pull-down transistor is always on and, therefore, the comparator will toggle, but within constrained (i.e., regulated) voltage limits.

Abstract: A voltage conversion circuit has a pulse generator that generates a pulse signal having a fixed pulse width and a variable pulse period. The output voltage of this voltage conversion circuit is determined according to the ratio of the pulse width to the pulse period of the pulse signal generated by the pulse generator. This circuit configuration makes it possible to produce as the output voltage lower voltages than ever.

Abstract: A controller that is linearly responsive to an input voltage provides continuously adjustable control of the width of a periodically repeating digital pulse, thereby achieving a linear voltage to duty-cycle ratio transfer function. The circuit of the present invention includes a master clock input, a ratio control voltage input, a controlled duty cycle clock output, a high gain amplifier configured as an integrator having differential inputs, each equipped with a low pass filter, a controlled current source, a resettable timing capacitor, a threshold detector and a reference pulse generator.

Abstract: Even if duty is shifted to either a state in which an “H” period is long or a state in which an “L” period is long, the duty is recovered to about 50%. A duty correction circuit corrects a duty shift or deviation developed when analog complementary cycle signals having a phase difference of about half cycle therebetween and a duty ratio of about 50% are converted to logic levels, through the use of, for example, serial two-stage NAND gate static latches.

Abstract: An apparatus for and method of serially transmitting a message between first and second devices coupled to a data or clock line in a process control device is disclosed. A first transition of the data or clock signal is generated during a signal cycle. A second transition of the signal is generated during the first signal cycle in order to control the duty cycle of the signal during the first signal cycle. If the duty cycle of the signal during the first signal cycle has a first value, then the first signal cycle is representative of a first data state transmitted between the first and second devices. If the duty cycle of the signal during the first signal cycle has a second value, then the first signal cycle is representative of a second data state transmitted between the first and second devices.

Abstract: A method for regulating the duty cycle of an input clock signal includes producing a second clock signal using a first adjustable delay circuit for varying the duty cycle. The second clock signal is applied to first and second circuits for respectively increasing and decreasing the duty cycle of the second clock signal. The method further includes monitoring if the first circuitry increases the duty cycle or if the second circuitry reducing the duty cycle saturates first. The duty cycle introduced by the first adjustable delay circuit is modified until saturation of the first and second circuits occur at substantially the same time.

Abstract: A duty cycle discriminating circuit used, for example, in a VTR. The duty cycle discriminating circuit comprises: an up/down counter with sign bit for counting up or counting down a count clock signal depending on a potential level of a signal to be discriminated; an up counter for counting up said count clock signal; an addend data generating circuit for producing an addend data having a value corresponding to a predetermined proportion of a count value of said up counter; and an addition circuit with sign bit for adding a count value of said up/down counter and said addend data produced by said addend data generating circuit. The sign bit of the addition circuit is outputted as a discrimination result signal of the duty cycle discriminating circuit. The predetermined proportion of the count value of the up counter is specified to perform duty cycle discrimination of the signal to be discriminated by using a desired threshold point.

Abstract: An output signal pulse width error correction circuit and method wherein errors in a data signal conforming to a communications protocol having a prescribed duty cycle are corrected by monitoring a duty cycle of the data signal, comparing the duty cycle to a duty cycle reference voltage corresponding to the prescribed duty cycle, and adjusting a pulse width of the data signal to conform to the prescribed duty cycle of the protocol. An embodiment is shown that low pass filters the input data signal to introduce greater slope to the input data signal which is then compared to a pulse width control voltage in order to generate an output data signal. The pulse width control voltage is produced by integrating the output data signal to obtain an average value corresponding to the duty cycle of the output data signal and comparing the average value to a duty cycle reference voltage corresponding to the prescribed duty cycle for the communications protocol.

Abstract: Process monitoring circuitry according to the invention incorporates additional routing structures that approximate signal delays due to long metal routing paths. The additional process monitor circuitry builds upon existing approaches without increasing the die size of an integrated circuit through the utilization of excess silicon space available between the bonding pads and the scribe lines of an integrated circuit wafer. More specifically, supplemental metal routing lines and vias are included in the delay paths of process monitor circuitry and located on the integrated circuit such that impact to other metal signal lines/vias used in the actual design is minimized. The supplemental metal routing lines are disposed in unused routable silicon space, such that no silicon area penalty is suffered as a result of having long metal routing lines.

Abstract: An output buffer circuit for transferring a high speed signal between large scale integrated circuits includes a first inverter with first and second transistors of opposite conductivity type, a second inverter with third and fourth transistors of opposite conductivity type, and a switch circuit for controlling the gates of the first and second transistors in accordance with a test control signal so as to change a dividing power. The respective outputs of the first and second inverters are connected in common to an output signal having a predetermined signal level related to an input signal.

Abstract: A circuit for generating a signal with a 50% duty cycle comprises an oscillator that provides a first control signal, a reference generator that provides a first reference signal, a control circuit that provides a second control signal and that is responsive to the first reference signal, a first current source load inverter that provides the second reference signal and that is responsive to the second control signal, and an output circuit that provides an output signal having a duty cycle substantially equal to 50% and a frequency substantially equal to that of the first control signal. The output circuit further includes a second current source load inverter that is responsive to both the first and second control signals.

Abstract: A circuit provides a duty cycle adjustment through a gate delay for operation at various output voltage levels. The delay may be provided through an OR gate and an AND gate that will generally modulate the duty cycle received at the input since most of the strength of the predriver resides in the pullup and pulldown transistors. The circuit may operate at a number of output voltage levels, including, but not limited to, CMOS and TTL levels. The implementation of the circuit also provides the advantage of parasitic load matching that may reduce EMI.

Abstract: A method and circuit spreads the narrow band emitted EMI of a clock signal. A first, high frequency, clock signal is received, for example, from an oscillator. The first clock signal is modulated, to produce a second clock signal, by inverting the first clock signal x times per L transitions of the first clock signal, where x and L are integers and x<L. Each inversion removes one transition of the first clock signal. The modulated clock signal has reduced EMI spectral density and may be utilized as a microprocessor high frequency master clock signal. Significantly, the modulated clock signal is synchronous with the first clock so that other circuitry which synchronizes to the modulated clock signal is also synchronized to the first clock signal clock. If needed by a particular system (e.g.

Abstract: A process monitor for a CMOS integrated circuit includes first and second delay units that are connected in a ring to constitute a ring oscillator that generates pulses having different phases at the outputs of the delay units respectively. The delay units affect the frequency of the pulses and also the rising and falling edges of the pulses differently depending on the process factor of PMOS and NMOS transistors in the delay units. The process factor can be computed from the frequency, or the ratio of the phase differences between the rising and falling edges of the pulses at the outputs of the first and second delay units. The oscillatory configuration of the monitor is highly sensitive to variations in process factor, and enables the monitor to be embodied by a relatively small number of elements that can fit in two input/output slots in a standard integrated circuit layout.

Abstract: An adjustable duty cycle clock generator has first and second delay lines coupled to receive an input clock and cascaded to first and second edge detectors, respectively. The second delay line has a programmable delay and the first and second edge detectors are further coupled to set and reset inputs on an S-R latch to generate an adjustable duty cycle clock with independently adjustable high and low times proportional to the induced delays of the first and second delay lines.

Abstract: A process for evaluating acceptability of a digital circuit having a first type of circuit element for a first change of state and a second type of circuit element for a second change of state, the process comprising: generating a leading edge of a first pulse with a pulse generation circuit formed on a substrate in common with the digital circuit and having elements of the first and the second type; generating a trailing edge of a first pulse with a pulse generation circuit formed on a substrate in common with the digital circuit and having elements of the first and the second type; generating an accepted-rejected signal, functionally related to the width of the pulse.

Abstract: A process monitor for a CMOS integrated circuit includes first and second delay units that are connected in a ring to constitute a ring oscillator that generates pulses having different phases at the outputs of the delay units respectively. The delay units affect the frequency of the pulses and also the rising and falling edges of the pulses differently depending on the process factor of PMOS and NMOS transistors in the delay units. The process factor can be computed from the frequency, or the ratio of the phase differences between the rising and falling edges of the pulses at the outputs of the first and second delay units. The oscillatory configuration of the monitor is highly sensitive to variations in process factor, and enables the monitor to be embodied by a relatively small number of elements that can fit in two input/output slots in a standard integrated circuit layout.

Abstract: A radio frequency (RF) transceiver includes a direct modulation transmitter and single down-conversion receiver for operation in a time-division-duplex (TDD) telecommunications environment. A single RF signal source, in the form of a phase-lock-loop (PLL), is used on a time-shared basis to provide both the carrier signal for the transmitter and the local oscillator (LO) signal for the receiver. In the transmitter, direct modulation is effected by modulating a voltage-controlled oscillator (VCO) in the PLL with a burst of the transmit data while opening the loop and holding the loop feedback tuning voltage constant. In the receiver, a self-adjusting comparator threshold is provided for automatically setting and adjusting a demodulated signal comparison threshold used in retrieving the data and data clock from the demodulated receive signal.