St-ericsson Sa

Stmicroelectronics International N.v.

Ericsson Modems Sa

Leonardus Hesen

Paul Mateman

Johannes Petrus Antonius Frambach

Johannes Antonius Frambach

Johannes Frambach

High-speed RF differential, Quadrature, divide-by-2 clock divider designs are based on inverters and clocking circuits connected in a serial ring formation. In one embodiment, only NMOS transistors are used in the inverters, and only PMOS transistors are used in the clocking circuits. This structure uses only 12 transistors. The input can be coupled directly to a VCO output, and provides minimum loading, as each VCO output is connected to only two transistors. Another embodiment comprises clocked inverter stages connected in a serial ring configuration with inverters between stages. The RF clock (or VCO signal) is used at the outer side of the inverters for speed improvement. In both circuits, positive and negative clock inputs are connected alternately at each stage of the ring.

High speed RF divider

A duty-cycle correction circuit comprises a plurality of AC-coupled, independently-biased inverter stages connected in series. A periodic signal is applied to an input of the plurality of inverter stages. Each inverter stage comprises an inverter with a resistive element connected in feedback between its output and input nodes. Each inverter stage is AC-coupled to a prior stage via a capacitor. The AC-coupling allows the signal to pass between inverter stages, but DC-isolates each inverter stage from adjacent stages, allowing each stage to maintain an independent DC bias of the signal at that stage. By virtue of the feedback resistive element, each stage defines a transition point between high and low signal states. Due to non-zero rise and fall times of the periodic signal, the independent DC bias of each stage is operative to incrementally shift the transition point of the periodic signal at each stage towards a desired duty-cycle.

RF duty cycle correction circuit

High-speed RF differential, Quadrature, divide-by-2 clock divider designs are based on inverters and clocking circuits connected in a serial ring formation. In one embodiment, only NMOS transistors are used in the inverters, and only PMOS transistors are used in the clocking circuits. This structure uses only 12 transistors, The input can be coupled directly to a VCO output, and provides minimum loading, as each VCO output is connected to only two transistors. Another embodiment comprises clocked inverter stages connected in a serial ring configuration with inverters between stages. The RF clock (or VCO signal) is used at the outer side of the inverters for speed improvement. In both circuits, positive and negative clock inputs are connected alternately at each stage of the ring.

An RF divider directly synthesizes a desired RF as a digital pattern that can be programmed and output at a VCO frequency. An exemplary RF divider comprises a pre-sequencer and a parallel-to-serial converter. The pre-sequencer successively outputs consecutive M-bit sections of a parallel word, where the parallel word comprises one or more copies of a frequency dividing bit pattern defining a frequency divisor. The parallel-to-serial converter performs a parallel-to-serial conversion on the M-bit sections of the parallel word based on the fixed radio frequency to generate an output signal having the desired radio frequency, where the output signal comprises a serial bit stream of the parallel word.

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Hegelsom, Netherlands

Leonardus Hesen