Abstract:
A Quadrature-In, Quadrature-Out (QIQO) clock divider divides by an odd divisor, such as three. An IQ input clock has in-phase and quadrature differential signals. Four stages of dynamic logic are arranged into a loop, with each stage output being one of four IQ output signals that have 90-degree phase separations. Each stage output drives the gates of a p-channel charging transistor and an n-channel discharging transistor of a next stage. Two p-channel charging logic transistors are in series between the next stage output and the p-channel charging transistor, and two n-channel evaluation transistors are in series between the next stage output and the n-channel discharging transistor. Different pairs of the four IQ input clock signals are applied to their gates. When the prior stage output is low, the stage output is charged. When the prior stage output is high, the stage output discharge timing is determined by the IQ signals.
Abstract:
A digital delay generator device is based on a series arrangement of cells, wherein each cell has a first input for receiving a single-phase clock signal, a second input for receiving a delayable signal for thereto imparting a cell delay, and an output for a so-delayed signal. Each cell comprising a series stack of transistors, and various cells comprise further transistor means for receiving a bypass control signal. Such further transistor means are arranged for under control of a bypass control signal effectively bypassing one or more cells to thereby effect a quantized overall delay shortering. In particular, such various cells form a contiguous pair in said string, and the transistor means effectively form respective transistor bypasses over clock-signal-controlled transistors in the associated series stack at mutually opposite sides of their respective stack.
Abstract:
Systems and methods for dividing input clock signals (CLKin) by programmable divide ratios (N) can produce output clock signals (CLKdiv) with the delay from the input clock signal to the output clock signal independent of the value of the divide ratio (N) and with the duty cycle of the output clock signal being 50% independent of the value of the divide ratio. An example programmable clock divider (45) includes a modulo N counter (220) that produces a count signal (Count) that counts modulo the divide ratio and a half-rate clock signal generator (230) that produces a common half-rate clock signal (HRCLKcom), an even half-rate clock signal (HRCLKeven), and an odd half-rate clock signal (HRCLKodd) that toggle at one-half the rate of the output clock signa (1/2 of CLKdiv). The common half-rate clock signal, the even half-rate clock signal, and the odd half-rate clock signal are combined (X or 242, 241) to produce the output clock signal.
Abstract:
A frequency divider (200) includes a least significant (LS) stage (220), multiple cascaded divider stages (230-1 to 230-N), and an output stage (210). The LS stage (220) receives an input signal (201), 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 (230-1 to 230-N) 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 (230-1) 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 (210) receives the output mode signal and a control signal, and generates an output signal (299) 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.
Abstract:
Apparatus comprising a frequency dividing cell (42) with a prescaler logic, an end-of-cycle logic, a clock input for receiving an input clock (CKin) with frequency fn, a clock output for providing an output clock (CKout) with frequency fm to a subsequent cell (43), a mode control input for receiving a mode control input signal (MDin) from the subsequent cell (43), and a mode control output for providing a mode control output signal (MDout) to a preceding cell (41). The end-of-cycle logic of the frequency dividing cell (42) has a switchable tail current source. This switchable tail current source allows the biasing current of the end-of-cycle logic to be switched off in order to save power.