A frequency divider includes a least significant (LS) stage, multiple cascaded divider stages, and an output stage. The LS stage receives an input signal, a program bit and a first mode signal, and generates a first frequency-divided signal and an output mode signal. Each of the plurality of divider stages divides the frequency of an output of an immediately previous stage by a value specified by a corresponding program bit and a corresponding mode signal. A first divider stage in the plurality of divider stages is coupled to receive the first frequency-divided signal and to generate the first mode signal. The output stage receives the output mode signal and a control signal, and generates an output signal by dividing a frequency of the output mode signal by two if the control signal is at one logic level. The output stage forwards the output mode signal without division otherwise.

High-speed frequency divider and a phase locked loop that uses the high-speed frequency divider

In one embodiment, method for frequency division comprises propagating a modulus signal up a chain of cascaded divider stages from a last one of the divider stages to a first one of the divider stages, and, for each of the divider stages, generating a respective local load signal when the modulus signal propagates out of the divider stage. The method also comprises, for each of the divider stages, inputting one or more respective control bits to the divider stage based on the respective local load signal, the one or more respective control bits setting a divider value of the divider stage.

New fractional phase locked loop (pll) architecture

A high linearity phase interpolator (PI) is disclosed. A phase value parameter indicative of a desired phase difference between an output signal and an input clock signal edge may be provided by control logic. A first capacitor may be charged for a first period of time with a first current that is proportional to the phase value parameter to produce a first voltage on the capacitor that is proportional to the phase value parameter. The first capacitor may be further charged for a second period of time with a second current that has a constant value to form a voltage ramp offset by the first voltage. A reference voltage may be compared to the voltage ramp during the second period of time. The output signal may be asserted at a time when the voltage ramp equals the reference voltage.

High Linearity Phase Interpolator

Disclosed examples include frequency divider circuits to divide a high frequency first clock signal to generate an output clock signal at a lower frequency, including a delay circuit to provide a delayed clock signal, a divider circuit to provide a divided clock signal, a sub-sampling circuit to sub-sample the first clock signal with the divided clock signal, and a feedback circuit to set the delay value of the adjustable delay circuit according to the sub-sampled output signal.

Fixed frequency divider circuit

Disclosed examples include frequency divider circuits, comprising an even number 4 or more differential delay circuits coupled in a cascade ring configuration of a configurable length N, with N−K of the N delay circuits providing an inverted polarity output signal to a succeeding delay circuit in the cascade ring configuration to control an amount of overlap between phase shifted clock signals from the delay circuits.

High speed frequency divider

Disclosed is an apparatus for multiple-divisor prescaler, which includes an odd/even core divider, a divisor control logic unit, an odd number inserted mechanism, and an n-order divided-by-2 divider with changeable trigger edges. This invention uses a clock toggle mechanism to vary the trigger edges of each divided-by-2 divider in the n-order divider, and associates the odd/even core divider to realize the multiple-divisor prescaler apparatus. Thereby, it achieves the purpose of being divided by 30/31. In addition, it increases the divisor range up to 2 n−1 +2 and 2 n +1 through the use of the clock toggle mechanism.

Ching-Feng Lee

Papers

Apparatus for multiple-divisor prescaler