摘要:
A frequency synthesizer includes analog components and digital components. The frequency synthesizer includes at least one shunt regulator that is coupled to a supply rail to provide power to at least one of the digital components. The frequency synthesizer also includes at least one series regulator that is coupled to the supply rail to provide power to at least one of the analog components.
摘要:
Several open-loop calibration techniques for phase-locked-loop circuits (PLL) that provide a process, temperature and divider modulus independence for the loop bandwidth and damping factor are disclosed. Two categories of open-loop techniques are presented. The first method uses only a single measurement of the output frequency from the oscillator and adjusts a single PLL loop element that performs a simultaneous calibration of both the loop bandwidth and damping factor. The output frequency is measured for a given value of the oscillator control signal and the charge-pump current is adjusted such that it cancels the process variation of the oscillator gain. The second method uses two separate and orthogonal calibration steps, both of them based on the measurement of the output frequency from the oscillator when a known excitation is applied to the open loop signal path. In the first step the loop bandwidth is calibrated by adjusting the charge-pump current based on the measurement of the forward path gain when applying a constant phase shift between the two clocks that go to the phase frequency detector, while the integral path is hold to a constant value. During the second step the damping factor is calibrated by adjusting the value of the integral loop filter capacitor based on the measurement of the oscillator output frequency when excited with a voltage proportional with the integral capacitor value, while the proportional control component is zeroed-out.
摘要:
A reference clock generator includes an oscillator to generate a periodic signal, a shaping circuit and a filter. The shaping circuit shapes the periodic signal to generate a clock signal. The filter is located between the oscillator and the shaping circuit.
摘要:
A reference clock generator includes an oscillator to generate a periodic signal, a shaping circuit and a filter. The shaping circuit shapes the periodic signal to generate a clock signal. The filter is located between the oscillator and the shaping circuit.
摘要:
A noise attenuator loop filter for PLL applications that allows a full on-chip integration of the loop filter capacitors, while ensuring a low output clock phase noise (jitter) is disclosed. A voltage attenuator (A) is inserted between the loop filter (passive or active) and the controlled oscillator. The attenuator attenuates the noise coming from the loop filter. In case of a passive RC filter, the series resistor noise power is attenuated by A2 times, allowing the usage of a resistor that is A2 times larger and therefore the loop filter capacitors result A2 times smaller (easy to integrate on-chip). The relatively low value capacitor allows the usage of thick-oxide accumulation-mode MOSFET capacitors that take a reasonable low area, have a good linearity, are isolated from the substrate by the grounded N-well, and have negligible gate leakage current. Several embodiments of the noise attenuator are proposed for different practical applications: clock generation for digital circuits, frequency translation, low or high supply voltage, narrow or wide frequency range, processes with or without isolated well devices, processes with or without polysilicon resistors, and medium or high reference spurs rejection.
摘要:
A technique includes receiving a signal spectrum that includes a plurality of channels within a first frequency range. The technique includes receiving a selection signal that identifies at least one desired channel to be tuned. The technique includes providing an oscillator that has a second frequency range that is substantially the same as the first frequency range and controlling the oscillators to generate one of a plurality of coarse-tune analog mixing signals. The signals substantially span across the second frequency range and each depends upon the location of the desired channel within the signal spectrum. The technique includes mixing the signal spectrum with the selected coarse-tune analog mixing signal to generate a coarsely tuned signal spectrum. The technique includes digitally processing the coarsely-tuned signal spectrum to fine tune the desired channel and to produce digital baseband signals for the desired channel.
摘要:
A technique includes receiving a signal spectrum that includes a plurality of channels within a first frequency range. The technique includes receiving a selection signal that identifies at least one desired channel to be tuned. The technique includes providing an oscillator that has a second frequency range that is substantially the same as the first frequency range and controlling the oscillators to generate one of a plurality of coarse-tune analog mixing signals. The signals substantially span across the second frequency range and each depends upon the location of the desired channel within the signal spectrum. The technique includes mixing the signal spectrum with the selected coarse-tune analog mixing signal to generate a coarsely tuned signal spectrum. The technique includes digitally processing the coarsely-tuned signal spectrum to fine tune the desired channel and to produce digital baseband signals for the desired channel.
摘要:
Several open-loop calibration techniques for phase-locked-loop circuits (PLL) that provide a process, temperature and divider modulus independence for the loop bandwidth and damping factor are disclosed. Two categories of open-loop techniques are presented. The first method uses only a single measurement of the output frequency from the oscillator and adjusts a single PLL loop element that performs a simultaneous calibration of both the loop bandwidth and damping factor. The output frequency is measured for a given value of the oscillator control signal and the charge-pump current is adjusted such that it cancels the process variation of the oscillator gain. The second method uses two separate and orthogonal calibration steps, both of them based on the measurement of the output frequency from the oscillator when a known excitation is applied to the open loop signal path. In the first step the loop bandwidth is calibrated by adjusting the charge-pump current based on the measurement of the forward path gain when applying a constant phase shift between the two clocks that go to the phase frequency detector, while the integral path is hold to a constant value. During the second step the damping factor is calibrated by adjusting the value of the integral loop filter capacitor based on the measurement of the oscillator output frequency when excited with a voltage proportional with the integral capacitor value, while the proportional control component is zeroed-out.
摘要:
A reference clock generator includes an oscillator to generate a periodic signal, a shaping circuit and a filter. The shaping circuit shapes the periodic signal to generate a clock signal. The filter is located between the oscillator and the shaping circuit.
摘要:
A receiver (1300) includes a mixing digital-to-analog converter (DAC) (1306), a direct digital frequency synthesizer (DDFS) (132A) and an interface (134D). The mixing DAC (1306) includes a radio frequency (RF) transconductance section (1308) and a switching section (1310). The RE transconductance section (1308) includes an input for receiving an RF signal and an output for providing an RE current signal. The switching section (1310) is coupled to the RF transconductance section (1308) and includes inputs for receiving bits associated with a digital local oscillator (LO) signal and an output that is configured to provide an analog output signal. The DDFS (132A) includes outputs configured to provide the bits associated with the digital LO signal to the inputs of the switching section (1310). The interface (134D) is coupled to the DDFS (132A) and is configured to align the bits provided by the DDFS (132A) with a first clock signal.