Anokiwave, Inc.

Antonio Geremia

Kartik Sridharan

Scott R Humphreys

Gaurav Menon

Shamsun Nahar

Jun Li

Akhil Garlapati

Eythan Familier

Kevin B Greene

A time-to-digital converter (TDC) uses voltage as a representation of time offset. A voltage change is induced over a time period from a start signal to a stop signal. The final voltage is then measured, and the voltage measurement is mapped to a time value representing the time between the start signal and the stop signal. The voltage change can be increasing or decreasing, e.g., by charging or discharging a capacitive circuit between the start signal and the stop signal. The voltage can be measured using an analog-to-digital converter (ADC) or other voltage measurement circuit. The voltage measurement can be mapped to the time value in any manner, such as, for example, using a transfer function or using a mapping table that provides a time value for each possible voltage measurement value.

Time-to-digital converter using voltage as a representation of time offset

A method and/or apparatus for tuning a frequency synthesizer device toward a prescribed frequency may input a signal into the input of the frequency synthesizer to produce an output signal having an output frequency, select a first one of a set of the above noted prescribed coarse curves, and compare the magnitude of the difference between the prescribed frequency and the output frequency. Next, the method selects a second of the set of coarse curves as a function of the magnitude of the difference between the prescribed frequency and the output frequency. Preferably, the method selects the second of the set of coarse curves by selecting one or more of the coarse curves out of the sequential frequency order as a function of the magnitude of the difference between the prescribed frequency and the output frequency.

Method and apparatus for tuning a synthesizer

Digital post-processing of time-to-digital converter (TDC) output data can be used to map each TDC code to the ideal one, but this requires knowing the TDC input-output mapping. Therefore, a calibration system and method are provided for characterizing operation of a TDC to compensate for non-idealities. Input signals having a known time difference are provided to the TDC, and a mapping between the TDC output and the known time difference is stored in a mapping table. With the described method, it is possible to input an input ramp of very low slope to construct this mapping to a desired resolution during a background calibration procedure. This characterizing and mapping can be performed across a range of input signals having different known time differences. After calibration, a mapping table can be used by a mapping circuit of the TDC or by a digital post-processing function to provide a compensated TDC output.

Time-to-digital converter and calibration

Embodiments of the present invention synchronize multiple synthesizers, such as phase-locked loops (PLLs), in a manner that does not require communication or coordination between the synthesizers. Specifically, each synthesizer is part of a synthesizer circuit that includes a synthesizer (e.g., a PLL), a phase measurement circuit, and a synchronization circuit. A common reference signal (e.g., an alternating clock signal) is provided to the synthesizer circuits. In one exemplary embodiment, in each synthesizer circuit, the phase measurement circuit measures a phase difference between the reference signal and a corresponding output of the synthesizer, and the synchronization circuit adjusts the synthesizer operation based on the measured phase difference in such a way that all of the synthesizers operate in-phase with one another relative to the common reference signal, without having any communication or coordination between the two synthesizer circuits other than provision of the common reference signal.

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San Diego, CA, United States of America

Antonio Geremia