Abstract: A pre-driver circuit generates a driver bias signal based on a swing command, a driver impedance characteristic, and an input signal. A driver receives the driver bias signal and generates, in response, a driver signal having a swing and having an output impedance corresponding to the bias signal. Optionally, the driver receives power from a switchable one of multiple supply rails, according to the swing. Optionally, the driver has voltage controlled resistor elements and the driver bias signal is generated based on the swing command and a replica of the driver voltage controlled resistor elements.

Abstract: A pre-driver circuit generates a driver bias signal based on a swing command, a driver impedance characteristic, and an input signal. A driver receives the driver bias signal and generates, in response, a driver signal having a swing and having an output impedance corresponding to the bias signal. Optionally, the driver receives power from a switchable one of multiple supply rails, according to the swing. Optionally, the driver has voltage controlled resistor elements and the driver bias signal is generated based on the swing command and a replica of the driver voltage controlled resistor elements.

Abstract: A pre-driver circuit generates a driver bias signal based on a swing command, a driver impedance characteristic, and an input signal. A driver receives the driver bias signal and generates, in response, a driver signal having a swing and having an output impedance corresponding to the bias signal. Optionally, the driver receives power from a switchable one of multiple supply rails, according to the swing. Optionally, the driver has voltage controlled resistor elements and the driver bias signal is generated based on the swing command and a replica of the driver voltage controlled resistor elements.

Abstract: Systems and methods for automatic detection and compensation of frequency offset in point-to-point communication. A burst mode clock and data recovery (CDR) system comprises input data received at a first frequency and a reference clock operating at a second frequency. A master phase-locked loop (PLL) comprising a first gated voltage controlled oscillator (GVCO) is configured to align the phases of reference clock and the input data, and provide phase error information and a recovered clock. A second GVCO is controlled by the recovered clock to sample the input data. A frequency alignment loop comprising a feedback path from the second GVCO to the master PLL is configured to use the phase error information to correct a frequency offset between the first frequency and the second frequency.

Abstract: A multi-terminal output with a common mode connection includes an output having a first terminal and a second terminal and having a common mode connection between the first terminal and the second terminal. A bulk connection of a transistor is coupled to the common mode connection. A first set of control signals and a second set of control signals are generated. Each of the first set of control signals has a first rail voltage level associated with a first power domain. The second set of control signals is generated from the first set of control signals. Each of the second set of control signals has a second rail voltage level that is associated with a second power domain. The second power domain is associated with a common mode voltage of outputs of an output driver.

Abstract: A gated voltage controlled oscillator has four identically structured delay cells, each of the delay cells having the same output load by connecting to the same number of inputs of other ones of the delay cells. Optionally a four phase sampling clock selects from the delay cell output and samples, at a four phase sampler, an input signal. Optionally an edge detector synchronizes the phase of the gated voltage controlled oscillator to coincide with NRZ bits. Optionally a variable sampling rate selects different phases from the delay cells to selectively sample NRZ bits at a lower rate. Optionally, a pulse width modulation (PWM) mode synchronizes a phase of the sampling clock to sample PWM symbols and recover encoded bits.

Abstract: A clock/data recovery circuit includes an edge detector circuit operable to receive a serial data burst and to generate a reset signal in response to a first edge of the serial data burst. The clock/data recovery circuit may also include an oscillator coupled to the edge detector circuit. The oscillator locks onto a target data rate prior to receipt of the serial data burst and locks onto a phase of the serial data burst in response to the reset signal. The clock/data recovery circuit may also include a phase detector circuit that receives the serial data burst. The phase detector circuit is coupled to the oscillator. The phase detector circuit adjusts the oscillator to maintain the lock onto the phase of the serial data burst during the serial data burst.

Abstract: In a particular embodiment, a digital circuit includes a frequency detection circuit operative to compare information related to transitions between sequential samples of a received signal. The frequency detection circuit is further operative to generate a control signal to reduce a sampling rate of the received signal in response to a predetermined number of the sequential samples having a same value. The digital circuit also includes a digital phase detector operative to provide the information related to the transitions between sequential samples to the frequency detection circuit.

Abstract: In a particular embodiment, a method includes adjusting an input to a divider on a feedback path of a phase locked loop circuit based on a stored digital value representing a portion of a time-based waveform that is applied to a modulator circuit. The stored digital value is retrieved based on an output of the feedback path.

Abstract: Power saving for hot plug detect (HPD) is disclosed. In a particular embodiment, a method includes detecting, at a source device that is connectable to a sink device, a connection of the source device to the sink device via a connector. The source device includes a DC voltage source and the connection is detected without consuming power from the DC voltage source.

Abstract: A pre-driver circuit generates a driver bias signal based on a swing command, a driver impedance characteristic, and an input signal. A driver receives the driver bias signal and generates, in response, a driver signal having a swing and having an output impedance corresponding to the bias signal. Optionally, the driver receives power from a switchable one of multiple supply rails, according to the swing. Optionally, the driver has voltage controlled resistor elements and the driver bias signal is generated based on the swing command and a replica of the driver voltage controlled resistor elements.

Abstract: A method of calibrating a phase-locked loop (PLL) while maintaining lock includes detecting that a control signal to an oscillator in a PLL has exceeded a threshold value while the PLL is locked to an input signal. In response, an operating current of the oscillator is adjusted to return the control signal below the threshold value while maintaining lock of the PLL to the input signal. Adjusting the operating current includes slowly varying an output current of a calibration circuit coupled to the PLL, enabling the PLL to maintain lock to the input signal during adjustment of the operating current.

Abstract: System and method for testing a high speed data path without generating a high speed bit clock, includes selecting a first high speed data path from a plurality of data paths for testing. Coherent clock data patterns are driven on one or more of remaining data paths of the plurality of data paths, wherein the coherent clock data patterns are in coherence with a low speed base clock. The first high speed data path is sampled by the coherent clock data patterns to generate a sampled first high speed data path, which is then tested at a speed of the low speed base clock.

Abstract: A balanced single-end impedance control system is disclosed. In a particular embodiment, the circuit includes a first transistor coupled to a first output terminal and a second transistor coupled to a second output terminal. The circuit also includes a third transistor and a fourth transistor, where device characteristics of the third transistor substantially match device characteristics of the first transistor and device characteristics of the fourth transistor substantially match device characteristics of the second transistor. The circuit further includes a first control path and a second control path. The first path is coupled to the third transistor and provides a first rail voltage to control a first gate control voltage of the first transistor. The second control path is coupled to the fourth transistor and provides a second rail voltage to control a second gate control voltage of the second transistor.

Abstract: A method includes tracking a tuning voltage at a first circuit coupled to a first drain node of a first supply of a charge pump. The method also includes tracking the tuning voltage at a second circuit coupled to a second drain node of a second supply of the charge pump. The method further includes stabilizing a first voltage of the first drain node and a second voltage of the second drain node responsive to the tuning voltage.

Abstract: A circuit includes a first path including a first transistor and a first current source. The first transistor is responsive to a tuning voltage. The circuit also includes a tuning voltage range extension circuit responsive to the tuning voltage. The tuning voltage range extension circuit is configured to selectively change current supplied by the first path as the tuning voltage exceeds a capacity threshold of the first transistor.

Abstract: A pulse width modulated (PWM) signal is received and, over a time interval of the PWM signal, a first count is incremented when the PWM signal is at a first level, and a second count is incremented when the PWM signal is at a second level. At the end of time interval the first count is compared to the second count and, based on the comparison, a decoded bit is generated. Optionally, incrementing the first count is by enabling a first oscillator that increments a first counter, and incrementing the second count is by enabling a second oscillator that increments a second counter.

Abstract: In an example, a high-speed pre-driver and voltage level converter with built-in de-emphasis for HDMI transmit applications is provided. An exemplary integrated circuit includes a serializer, a pre-driver coupled to receive a differential input from the serializer, and a driver. The pre-driver includes all-p-type metal-oxide-silicon (PMOS) cross-coupled level converter comprising four PMOS transistors and two de-emphasis PMOS transistors forming a de-emphasis tap coupled to the output of the cross-coupled level converter. The driver is coupled to the pre-driver output and is configured to receive a differential input from the pre-driver.

Abstract: Clock and data recovery (CDR) circuits and resettable voltage controlled oscillators (VCOs) are disclosed. In one embodiment, the CDR circuit includes a sampler configured to receive a data stream in a data path and sample the data stream. However, a clock signal of the data stream needs to be recovered to sample the data stream since the data stream may not be accompanied by the clock signal. To recover the clock signal from the data stream, the CDR circuit may have a resettable VCO configured to generate a clock output. The sampler and the resettable VCO may be operably associated so that the sampler samples the data stream in the data path based on the clock output. The resettable VCO can be reset to adjust a clock phase of the clock output and help reduce sampling errors resulting from drift of the clock output and/or the data stream.

Abstract: Systems and methods for automatic detection and compensation of frequency offset in point-to-point communication. A burst mode clock and data recovery (CDR) system comprises input data received at a first frequency and a reference clock operating at a second frequency. A master phase-locked loop (PLL) comprising a first gated voltage controlled oscillator (GVCO) is configured to align the phases of reference clock and the input data, and provide phase error information and a recovered clock. A second GVCO is controlled by the recovered clock to sample the input data. A frequency alignment loop comprising a feedback path from the second GVCO to the master PLL is configured to use the phase error information to correct a frequency offset between the first frequency and the second frequency.