Abstract:
The disclosed invention is a technology for producing a recovered clock signal using a multi-mode clock data recovery (CDR) circuit that accommodates a flexible range operating frequencies F and consecutive identical digit requirements CID. In a first mode of operation, a controlled oscillator produces the recovered clock signal, and in a second mode of operation, a phase interpolator produces the recovered clock signal. The multi-mode CDR circuit operates in the first mode if (CID/F) is less than a threshold time value and in the second mode if (CID/F) is greater than the threshold time value.
Abstract:
The disclosed invention is a technology for producing a recovered clock signal using a multi-mode clock data recovery (CDR) circuit that accommodates a flexible range operating frequencies F and consecutive identical digit requirements CID. In a first mode of operation, a controlled oscillator produces the recovered clock signal, and in a second mode of operation, a phase interpolator produces the recovered clock signal. The multi-mode CDR circuit operates in the first mode if (CID/F) is less than a threshold time value and in the second mode if (CID/F) is greater than the threshold time value.
Abstract:
Circuitry and methods are provided for an LVDS-like transmitter that may be able to DC couple to a receiver having a CML termination scheme. Replacing the common mode voltage source of an LVDS transmitter with a resistive pulldown to ground may allow the transmitter to interface in a DC coupled fashion with a CML receiver. Further, the resistive pulldown may be programmable. This LVDS-like transmitter may be able to support a wider customer base by allowing it to DC couple to a wider range of termination voltage levels, such as CML termination voltage levels.
Abstract:
Programmable logic device circuitry for receiving and/or transmitting a differential signal includes controllable invert circuitry that effectively reverses the polarity of the differential signal. The controllable invert circuitry operates on a single-ended (non-differential) signal that has either been derived from a differential input signal or from which a differential output signal will be derived.
Abstract:
An oscillator circuit can generate a periodic signal, and a frequency adjustment circuit can adjust the frequency of the periodic signal. The periodic signal may include phase jitter. In one aspect of the invention, the phase jitter may be mitigated by connecting other circuitry to the oscillator circuit and allowing the other circuitry to draw current. In one embodiment, the other circuitry is connected in parallel with the oscillator circuit. In one embodiment, the other circuitry is configured to draw greater current to mitigate more phase jitter and to draw less current to mitigate less phase jitter. In one embodiment, a greater portion of the other circuitry is connected to the oscillator circuit for higher frequencies and a lesser portion of the other circuitry is connected to the oscillator circuit for lower frequencies.
Abstract:
The disclosed invention is a technology for producing a recovered clock signal using a multi-mode clock data recovery (CDR) circuit that accommodates a flexible range operating frequencies F and consecutive identical digit requirements CID. In a first mode of operation, a controlled oscillator produces the recovered clock signal, and in a second mode of operation, a phase interpolator produces the recovered clock signal. The multi-mode CDR circuit operates in the first mode if (CID/F) is less than a threshold time value and in the second mode if (CID/F) is greater than the threshold time value.