Abstract: A technique for expanding an input signal includes receiving the input signal at a first node of a voltage expander and generating a plurality of expanded signals on different outputs of the voltage expander responsive to the input signal. In certain embodiments, each of the expanded signals has a different magnitude at a respective fixed offset from the input signal.

Abstract: In a feedback system such as a PLL, the integrating function associated with a loop filter capacitor is instead implemented digitally and is easily implemented on the same integrated circuit die as the PLL. There is no need for either an external loop filter capacitor nor for a large loop filter capacitor to be integrated on the same integrated circuit die as the PLL. In some embodiments, an analog phase detector is utilized whose phase error output signal is delta-sigma modulated to encode the magnitude of the phase error using a digital (i.e., discrete-time and discrete-value) signal. This digital phase error signal is “integrated” by a digital integration block including, for example, a digital accumulator, whose output is then converted to an analog signal, optionally combined with a loop feed-forward signal, and then conveyed as a control voltage to the voltage-controlled oscillator.

Abstract: A feedback system such as a phase locked loop (PLL) includes a second feedback loop which responds when a VCO control voltage is near either end of its range, by slowly adjusting additional tuning elements which control the VCO frequency. The second feedback loop is arranged to cause a slow enough change in the VCO frequency that the first traditional feedback loop adjusts the control voltage quickly enough in a direction toward its mid-range value to keep the VCO frequency substantially unchanged. The second feedback loop advantageously incorporates one or more digital control signals which preferably change no more than one bit at a time and with a controlled slow ramp rate. As a result, the PLL maintains phase accuracy so that the operation of the PLL, including subtle specifications such as input data jitter tolerance or output jitter generation when used for clock and data recovery applications, is not negatively impacted.

Abstract: A feedback system such as a phase locked loop (PLL) includes a second feedback loop which responds when a VCO control voltage is near either end of its range, by slowly adjusting additional tuning elements which control the VCO frequency. The second feedback loop is arranged to cause a slow enough change in the VCO frequency that the first traditional feedback loop adjusts the control voltage quickly enough in a direction toward its mid-range value to keep the VCO frequency substantially unchanged. The second feedback loop advantageously incorporates one or more digital control signals which preferably change no more than one bit at a time and with a controlled slow ramp rate. As a result, the PLL maintains phase accuracy so that the operation of the PLL, including subtle specifications such as input data jitter tolerance or output jitter generation when used for clock and data recovery applications, is not negatively impacted.

Abstract: In a feedback system such as a PLL, the integrating function associated with a loop filter capacitor is instead implemented digitally and is easily implemented on the same integrated circuit die as the PLL. There is no need for either an external loop filter capacitor nor for a large loop filter capacitor to be integrated on the same integrated circuit die as the PLL. In some embodiments, an analog phase detector is utilized whose phase error output signal is delta-sigma modulated to encode the magnitude of the phase error using a digital (i.e., discrete-time and discrete-value) signal. This digital phase error signal is “integrated” by a digital integration block including, for example, a digital accumulator, whose output is then converted to an analog signal, optionally combined with a loop feed-forward signal, and then conveyed as a control voltage to the voltage-controlled oscillator.

Abstract: In a feedback system such as a PLL, the integrating function associated with a loop filter capacitor is instead implemented digitally and is easily implemented on the same integrated circuit die as the PLL. There is no need for either an external loop filter capacitor nor for a large loop filter capacitor to be integrated on the same integrated circuit die as the PLL. In a preferred embodiment, an analog phase detector is utilized whose phase error output signal is delta-sigma modulated to encode the magnitude of the phase error using a digital (i.e., discrete-time and discrete-value) signal. This digital phase error signal is “integrated” by a digital integration block including, for example, a digital accumulator, whose output is then converted to an analog signal, optionally combined with a loop feed-forward signal, and then conveyed as a control voltage to the voltage-controlled oscillator.

Abstract: A feedback system such as a phase locked loop (PLL) includes a second feedback loop which responds when a VCO control voltage is near either end of its range, by slowly adjusting additional tuning elements which control the VCO frequency. The second feedback loop is arranged to cause a slow enough change in the VCO frequency that the first traditional feedback loop adjusts the control voltage quickly enough in a direction toward its mid-range value to keep the VCO frequency substantially unchanged. The second feedback loop advantageously incorporates one or more digital control signals which preferably change no more than one bit at a time and with a controlled slow ramp rate. As a result, the PLL maintains phase accuracy so that the operation of the PLL, including subtle specifications such as input data jitter tolerance or output jitter generation when used for clock and data recovery applications, is not negatively impacted.

Abstract: In a feedback system such as a PLL, the integrating function associated with a loop filter capacitor is instead implemented digitally and is easily implemented on the same integrated circuit die as the PLL. There is no need for either an external loop filter capacitor nor for a large loop filter capacitor to be integrated on the same integrated circuit die as the PLL. In a preferred embodiment, an analog phase detector is utilized whose phase error output signal is delta-sigma modulated to encode the magnitude of the phase error using a digital (i.e., discrete-time and discrete-value) signal. This digital phase error signal is “integrated” by a digital integration block including, for example, a digital accumulator, whose output is then converted to an analog signal, optionally combined with a loop feed-forward signal, and then conveyed as a control voltage to the voltage-controlled oscillator.

Abstract: An internal frequency reference, such as a VCO used in a PLL, having a free-running frequency fairly well controlled within a predictable range, is used as a rough frequency reference to determine, for an externally-provided frequency reference signal, which of a finite number of discrete frequencies is currently received. The VCO has a frequency range which varies less, as a percentage, than the ratio between possible reference frequency values. Consequently, the VCO is used as a frequency reference to measure the frequency reference signal. An internal signal is generated to indicate to remaining circuitry which of the possible reference frequencies is actually being provided, without requiring use of any dedicated input pins to receive a select signal. An integrated circuit device may be configured for different modes of operation as a function of which reference frequency is provided to the device.

Abstract: In a feedback system such as a PLL, the integrating function associated with a loop filter capacitor is instead implemented digitally and is easily implemented on the same integrated circuit die as the PLL. There is no need for either an external loop filter capacitor nor for a large loop filter capacitor to be integrated on the same integrated circuit die as the PLL. In a preferred embodiment, an analog phase detector is utilized whose phase error output signal is delta-sigma modulated to encode the magnitude of the phase error using a digital (i.e., discrete-time and discrete-value) signal. This digital phase error signal is “integrated” by a digital integration block including, for example, a digital accumulator, whose output is then converted to an analog signal, optionally combined with a loop feed-forward signal, and then conveyed as a control voltage to the voltage-controlled oscillator.

Abstract: In a feedback system such as a PLL, the integrating function associated with a loop filter capacitor is instead implemented digitally and is easily implemented on the same integrated circuit die as the PLL. There is no need for either an external loop filter capacitor nor for a large loop filter capacitor to be integrated on the same integrated circuit die as the PLL. In a preferred embodiment, an analog phase detector is utilized whose phase error output signal is delta-sigma modulated to encode the magnitude of the phase error using a digital (i.e., discrete-time and discrete-value) signal. This digital phase error signal is “integrated” by a digital integration block including, for example, a digital accumulator, whose output is then converted to an analog signal, optionally combined with a loop feed-forward signal, and then conveyed as a control voltage to the voltage-controlled oscillator.