A frequency divider unit to receive an oscillating signal and to update, at an output of the frequency divider unit, a frequency-divided oscillating signal is presented. The frequency divider unit has a first clocked signal inverter to update, clocked based on the oscillating signal, a first intermediate signal at an output of the first clocked signal inverter. The frequency divider unit has a second clocked signal inverter, wherein the output of the first clocked signal inverter may be connected to an input of the second clocked signal inverter, and wherein the second clocked signal inverter updates, clocked based on the oscillating signal, a second intermediate signal at an output of the second clocked signal inverter. The frequency divider unit has a continuously operating signal inverter coupled between the output of the second clocked signal inverter and the input of the first clocked signal inverter.

A divider and buffer circuit uses a receive command to initiate a reset of buffer circuitry prior to restarting to avoid a metastable state. For example, the divider and buffer circuit includes a first buffer circuit, a second buffer circuit, and a reset circuit. The reset circuit receives a command and provide a pulse on a reset signal in response to the command. In response to the reset pulse, the first buffer circuit provides a first divided clock signal having a first logical value based on respective logical values of received complementary clock signals and the second buffer circuit provides a second divided clock signal having a second logical value based on the respective logical values of the complementary clock signals. The command is a CAS SYNC command, in some examples.

A divider and buffer circuit uses a receive command to initiate a reset of buffer circuitry prior to restarting to avoid a metastable state. For example, the divider and buffer circuit includes a first buffer circuit, a second buffer circuit, and a reset circuit. The reset circuit receives a command and provide a pulse on a reset signal in response to the command. In response to the reset pulse, the first buffer circuit provides a first divided clock signal having a first logical value based on respective logical values of received complementary clock signals and the second buffer circuit provides a second divided clock signal having a second logical value based on the respective logical values of the complementary clock signals. The command is a CAS SYNC command, in some examples.

A method for reducing deterministic jitter in a clock generator includes providing a load current through a regulated voltage node to a circuit responsive to a divide ratio. The method includes providing an auxiliary current through the regulated voltage node. The auxiliary current has a first current level during a first period corresponding to a first value of the divide ratio and the auxiliary current has a second current level during a second period corresponding to a second value of the divide ratio.

A frequency divider includes a circuit that receives an input clock signal having a period T on an input port thereof and generates an output clock signal on an output port thereof having a period MT in response to a control signal specifying M is disclosed. Here, M is a positive integer and all transitions between logical one and logical zero in the output clock signal occur at integer multiples of T. In one embodiment, the circuit includes a module string having characterized by N identical modules connected in series to form a string of modules. Each module is configured such that when the clock signal having period T is input to the first module, the output clock signal having a period of MT is output from the last module, where M can have any value between one and a maximum number that depends on N.

A method for reducing deterministic jitter in a clock generator includes providing a load current through a regulated voltage node to a circuit responsive to a divide ratio. The method includes providing an auxiliary current through the regulated voltage node. The auxiliary current has a first current level during a first period corresponding to a first value of the divide ratio and the auxiliary current has a second current level during a second period corresponding to a second value of the divide ratio.

A frequency divider circuit includes a counter configured to generate a counter signal responsive to a frequency of a clock signal and a frequency ratio, and a compensation circuit coupled to the counter, and configured to generate an output signal. The output signal has a frequency equal to the frequency of the clock signal divided by a frequency ratio, and a duty cycle greater than 1/r, where r is the frequency ratio.

A clock circuit includes a circuit configured to use a regulated voltage on a regulated voltage node to provide a frequency modulated clock signal having a frequency vacillating between a first frequency and a second frequency. The clock circuit includes an auxiliary loading circuit coupled to the regulated voltage node and configured to selectively provide load compensation for a load difference of the circuit. The load difference is a difference between a first load corresponding to the first frequency and a second load corresponding to the second frequency. The circuit may include a frequency divider circuit configured to use the regulated voltage on the regulated voltage node to generate the frequency modulated clock signal by frequency dividing an input clock signal according to a divide value vacillating between a first divide value and a second divide value.

An apparatus includes a control circuit configured to generate a frequency divider control signal approximating a fractional divide ratio. The apparatus includes a frequency divider configured to generate an output clock signal based on an input clock signal and an adjusted frequency divider control signal. The output clock signal is a frequency-divided version of the input clock signal. The apparatus includes a measurement circuit configured to provide digital time information corresponding to an edge of the output clock signal. The apparatus includes an adaptive adjustment circuit configured to generate the adjusted frequency divider control signal based on the frequency divider control signal and the digital time information.

Aspects of the disclosure are directed to multi-module frequency division. As may be implemented in accordance with one or more embodiments herein, an apparatus includes latching circuitry having three or fewer vertically-stacked transistors between power rails, which operate to provide output signals from input signals, the output signals having a frequency that is a divided representation of the frequency of the input signals. A pulse widening circuit modifies the output signals by widening a pulse thereof, providing a modified output signal. A further latching circuit may be utilized to perform a further frequency division of the modified output signal. The respective latching circuitry can be used to selectively provide frequency-divided output signals from input signals at respective divided frequencies.