Device for receiving series data

1. A circuit for receiving digital data arriving in series comprising:

a circuit for generating a reference clock, comprising

two settable delay means receiving a base clock, the difference between the maximum and minimum delays of each delay means being greater than one period of the base clock,

a multiplexer selecting the output signal of one or the other of the delay means,

control means for, according to whether the reference clock frequency must be smaller or greater than the base clock frequency, increasing or decreasing at the rate of the base clock or at a multiple of this rate the delay of the selected delay means, and controlling a minimum or maximum delay for the non-selected delay means, and

a phase comparator capable of changing the multiplexer selection when the transitions of the signals output by the delay means corresponding to a same transition of the base clock are shifted by a duration greater than or equal to one period of the base clock;

a circuit for oversampling the received data memorizing the samples sampled at the rate of several clocks phase-shifted with respect to the reference clock, the oversampling circuit comprising means for selecting and providing as output data samples representative of the received data; and

a detection circuit identifying the variations of the phase shift between the reference clock edges and the transitions of the received data by analyzing the memorized samples, the detection circuit controlling a variation of the reference clock frequency when the phase shift variations are repeated over several sampling cycles.

2. The circuit of claim 1 , wherein the delay of the delay means varies by increments or decrements and wherein the control means comprise means for setting the increment or decrement value.

3. The circuit of claim 1 , wherein each delay means comprises several delay elements in series, the output of each delay element being connected to the output of the delay means via a switch, the input of the first delay elements being connected to the input of the delay means.

4. The circuit of claim 1 , wherein the phase comparator comprises two two-input NAND gates, the output of a NAND gate being connected to a first input of the other NAND gate, each NAND gate receiving on its second input one of the signals output by said delay means, one of these signals being transmitted to the control input of a first flip-flop via a non-inverting circuit exhibiting a delay, the output of one of the NAND gates being connected to the data input of the first flip-flop, the output of the first flip-flop controlling a second flip-flop having its output connected to its input via an inverter, the output of the second flip-flip controlling the multiplexer of the reference clock generation circuit.

5. The circuit of claim 1 , wherein the delay of one of the delay means increases or decreases only for one or several cycles of a set of cycles of the input signal, the number of delay increases or decreases over a set of cycles being all the greater as the reference clock frequency is distant from the base clock frequency.