Freescale Semiconductor,inc.

Nxp Usa, Inc.

Nxp B.v.

Krishna Thakur

Deependra Kumar Jain

Anand Kumar Sinha

Gaurav Agrawal

Sanjay Kumar Wadhwa

Saurabh Goyal

Vinod K Jain

Siyaram Sahu

Divya Tripathi

Ateet Omer

Anubhav Srivastava

Sadique Mohammad Iqbal

Pawan Sabharwal

John M Pigott

Avinash Chandra Tripathi

Devesh P Singh

Ravi Kumar

Atul Dahiya

Pragya Priya Malakar

Vishwajit Babasaheb Bugade

Ankesh Jain

Raghav Mehta

Avinish Chandra Tripathi

A low current, adaptively-biased switched resistor digital-to-analog converter (RDAC) circuit, method and apparatus are provided with a coarse trim ladder and a fine trim ladder connected with a plurality of NFET switches to generate an output reference voltage from an input supply voltage, where the bulk semiconductor substrate regions for the NFET switches in at least the fine trim ladder are driven by a unity gain buffer which is connected in feedback to receive the output reference voltage and to generate a buffered reference voltage which is directly connected to bulk semiconductor regions of the NFET switches, thereby providing a low current, low circuit area solution with reduced leakage current and temperature variation.

RDAC ladder with adaptive biasing to reduce the reference variation across temperature

Systems and methods for providing temperature compensation in oscillators circuits are discussed. In various embodiments, these systems and methods may be implemented in technologies where only resistors with the same type (positive or negative) of temperature coefficients of resistance are available. For example, in some implementations, an oscillator circuit may include a voltage generator coupled to an input terminal of a common gate amplifier through a first resistor, and a frequency-to-voltage converter coupled to another input terminal of the common gate amplifier through a second resistor, where the second resistor may be configured to reduce a frequency variation of the oscillator circuit in response to temperature changes.

Temperature compensation in oscillator circuits

A clock generator includes a buffer stage to drive an output clock and a slew accelerator circuit to receive a first clock signal and generate an input clock signal to the buffer stage. The slew accelerator circuit includes first, second, and third inverter stages. The first stage generates a pair of non-overlapping clock signals from the first clock signal. A rise time of a first non-overlapping clock signal of the pair is faster than a rise time of a second non-overlapping clock signal of the pair, and a fall time of the second non-overlapping clock signal is faster than a fall time of the first non-overlapping clock signal. The second stage generates a first intermediate clock signal based on the pair of non-overlapping clock signals. The third stage generates the input clock signal to the buffer stage based on the first intermediate clock signal and the pair of non-overlapping clocks.

Integrated circuit for clock generation

A self-biased, closed loop, low current free running oscillator clock generator method and apparatus are provided with a current mode comparator connected to a trimming resistor and configured to compare an internally generated voltage reference Vsignal to a voltage feedback signal V, where the current mode comparator comprises a common gate amplifier connected to a current mirror circuit in a negative self-biased closed loop to generate a control current signal for controlling a current controlled oscillator to produce an output clock signal having a clock frequency based on the control current signal, where a frequency-to-voltage converter is connected in a feedback path to receive the output clock signal and is configured to produce the voltage feedback signal Vfor input to the current mode comparator, wherein the clock frequency of the output clock signal is tuned to a nominal locked output frequency fby the trimming resistor.

Self-biased, closed loop, low current free running oscillator

An integrated circuit including a functional circuit, a tuning circuit, and a control circuit is provided. The functional and control circuits generate an output signal and a digital code, respectively. The tuning circuit tunes the functional circuit based on the digital code to control an attribute of the output signal. The digital code is iteratively adjusted such that the attribute of the output signal is maintained within a predefined range. When the digital code corresponds to a cliff value, the digital code for a subsequent iteration is adjusted by a non-unit offset value such that a difference between the attribute for the cliff value and for the subsequent digital code is within a tolerance limit. The digital code is indicative of coarse and fine parameters, and for each value of the coarse parameter, the cliff value corresponds to the lowest or highest value of the fine parameter.

System and method for controlling tuning in electronic circuitries

A phase shifted clock generator that includes a delay circuit, a capacitor, and a control circuit is provided. The delay circuit receives a reference clock signal and generates a phase shifted clock signal. A phase difference between the phase shifted clock signal and the reference clock signal is controlled based on a delay of the delay circuit. The control circuit controls, based on the phase shifted clock signal and the reference clock signal, a control voltage generated at the capacitor. The control circuit controls the control voltage by charging and discharging the capacitor with a constant current. The delay of the delay circuit is controlled based on the control voltage such that the phase difference between the phase shifted clock signal and the reference clock signal is within a predefined range.

Phase shifted clock generator

A bootstrap switch circuit includes a transistor-based switch controlled by a first gate signal and a leakage protection transistor controlled by a second gate signal configured to reduce gate induced drain leakage in the transistor-based switch A first gate driver is included that produces a first gate signal at its output so that the first gate signal turns on the transistor-based switch during a sampling mode and turns off the transistor-based switch during a hold mode. A second gate driver is included that produces a second gate signal at its output and to receive the output signal of the bootstrap switch circuit so that the second gate signal turns on the leakage protection transistor during the sampling mode and turns off the leakage protection transistor during the hold mode and the second gate signal is based upon the output signal of the bootstrap switch circuit.

Circuit to reduce gate induced drain leakage

A multiphase digital frequency synthesizer including a multiphase ring oscillator that provides phased clock signals, a clock divider that divides a phased clock signal by an integer value and a carry value to provide a divided clock signal, positive select circuitry that determines and updates a positive select value with accumulation and a modulo function based on a fractional division factor updated with successive cycles of the divided clock signal, carry circuitry that determines the carry value based on a number of the phased clock signals, positive multiplex circuitry that selects from among the phased clock signal using the positive select value for providing a positive multiplexed clock signal, and fractional phase addition circuitry that provides a first output clock signal based on a selected phased clock signal, the divided clock signal, and the positive multiplexed clock signal. Similar negative select circuitry and duty cycle correction circuitry may be included.

Multiphase digital frequency synthesizer with fractional division

A low power crystal oscillator is provided. The crystal oscillator includes a gain stage circuit having a first gain stage input coupled at a first oscillator terminal and configured to receive a first oscillator signal of a crystal. A first bias circuit is configured to generate a first bias voltage based on the first oscillator signal. A reference circuit is configured to generate a reference current based on the first bias voltage. A comparator circuit is configured to generate a clock signal based on the first oscillator signal and the first bias voltage. The comparator circuit includes a second bias circuit configured to generate a second bias voltage. The gain stage circuit includes a second gain stage input coupled to receive the second bias voltage.

Low power crystal oscillator

A digital phase-locked loop (PLL) includes a time-to-digital converter (TDC) and a digitally controlled oscillator (DCO). The DCO generates a PLL clock signal and various sampling clock signals that are mesochronous. The TDC samples a phase difference between a reference clock signal and a frequency-divided version of the PLL clock signal based on the sampling clock signals and various enable signals. The enable signals are generated based on a calibration of the digital PLL. Each enable signal is associated with a sampling clock signal and indicates whether the associated sampling clock signal is to be utilized for sampling the phase difference. Further, the TDC generates control data indicative of the sampled phase difference. The DCO generates the PLL clock signal and the sampling clock signals based on the control data until the digital PLL is in a phase-locked state.

Digital phase-locked loop

An initialization circuit of a delay locked loop (DLL) includes a sense circuit and a control circuit. The sense circuit receives an enable signal, a reference clock signal, and various delayed reference clock signals, and outputs another enable signal. The control circuit receives the two enable signals and outputs and provides a control signal to a loop filter of the DLL to control a delay value associated with the DLL. The control signal is provided to the loop filter such that the delay value associated with the DLL equals a predetermined delay value for a predetermined time duration. Further, after a lapse of the predetermined time duration, the delay value associated with the DLL increases until a difference between a time period of the reference clock signal and the delay value equals a threshold value.

Initialization circuit of delay locked loop

An enabling system that includes a controller and processing circuitry, is configured to enable an external oscillator that operates in one of single-ended, differential, and crystal modes. To enable the external oscillator, the controller is configured to detect a mode of operation of the external oscillator, and the processing circuitry is configured to operate in the detected mode. The controller detects the mode of operation of the external oscillator by sequentially initializing the processing circuitry to operate in the single-ended, differential, and crystal modes, and determining whether the current operating mode of the processing circuitry is same as the mode of operation of the external oscillator based on a clock signal outputted by the processing circuitry during the corresponding mode.

System for enabling external oscillators in system-on-chips

A calibration system of a digital phase locked loop (DPLL) includes a calibration circuit and a digitally controlled oscillator (DCO). The calibration circuit is configured to receive an input signal and a feedback signal, and generate a digital signal, based on a frequency of the input signal, a frequency of the feedback signal, and an input bias code. The DCO is configured to receive the input bias code and the digital signal, and generate a bias signal based on the input bias code. The DCO is further configured to generate an analog signal based on the bias signal and the digital signal, and generate the feedback signal such that the frequency of the feedback signal is based on an amplitude of the analog signal.

System and method for calibrating digital phase locked loop

A delay-locked loop (DLL) includes a delay line configured to receive a reference clock signal and a control signal, and generate a first plurality of clock signals. Each clock signal of the first plurality is configured to have a different phase delay relative to the reference clock signal. A phase frequency detector is coupled to the delay circuit and is configured to receive a first clock signal and a second clock signal of the first plurality, and generate up and down control signals. A charge pump is coupled to receive the up and down control signals and generates a charge pump current based on the up and down control signals. An output of the charge pump is coupled to the delay line at a voltage control node. An initialization circuit is coupled to the voltage control node and is configured to generate an initialization voltage based on the reference clock signal frequency.

Delay-locked loop having initialization circuit

A delay-locked loop (DLL) has a fractional phase frequency (PF) detector that reduces false locking and harmonic locking. The PF detector has a trunk, an upper branch, a lower branch, and a logic module. A delay line provides the PF detector a set of fractional phase-delayed clock signals that are used to prime and/or activate corresponding flip-flops of the trunk, upper branch, and lower branch in a sequence. The use of flip-flops in the lower branch activated by different fractional phase-delayed clock signals avoids false locking and harmonic locking over a wider range of initial delay magnitudes than conventional DLLs.

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Greater Noida, India

Krishna Thakur