Abstract:
The invention relates to tests for verifying the integrity of circuits (16) for serial bi-directional transmissions. These tests are capable of testing transceivers (12) operating a very high frequency without creating interference and consist in either leaving the serial output of the transceiver (12) disconnected from the line (L), or disconnecting (INF) its adaptation impedance, commanding the transmission of signals, and comparing the signals transmitted to the reception signals detected by the same transceiver. In a variant, the adaptation impedance of the transceiver of the remote station may be disconnected.
Abstract:
A variable delay circuit including a fixed delay circuit (D1) furnishing a signal (e.sub.1) that is delayed with respect to the input signal (e.sub.0). A combination circuit (C) furnishes a combination signal (f.sub.K) resulting from the superposition, with weighting and an integral effect of the input (e.sub.0) and delayed (e.sub.1) signals. The assembly is dimensioned such that the fixed delay (T) is less than the transition time that the combination signal (f.sub.K) has when only the input signal (e.sub.0) is applied.
Abstract:
A delay circuit includes a primary circuit receiving an input signal and outputting two intermediate signals having a delay therebetween. A combination circuit with two modules that output a combination signal on the basis of the addition with weighting and effect of integration of the intermediate signals and of their conjugate. Each module includes a discharging circuit and a charging circuit, which each have switching elements controlling the connection between a common line and first and second supply potentials. These connections use a variable resistor and a non-variable resistor so as to ensure the permanent participation of the two modules in the charging or discharging of a capacitor. This delay circuit is particularly useful in CMOS circuits.
Abstract:
The frequency multiplier 20 is embodied by a phase-locked loop including a phase comparator 11 for commanding a plurality of delay elements 130 to 137 that furnish successive phase-shifted signals CL0-CL7 to a logical adder 16 made up of EXCLUSIVE OR gates.
Abstract:
The gates (11) of the exclusive OR type having two inputs (A, B) are disposed in tree structure in successive layers of an integrated circuit beginning with an input layer which receives the input signals of the tree. The output of each gate is connected to an input of a gate in the adjacent layer. Each gate includes two cells (11a, 11b) that switch substantially simultaneously in response to two respective complementary signals (A, NA; B, NB) from one of the two inputs and that supply respective output signals that are representative of the complementary functions (XOR, NXOR) of the exclusive OR type. This makes it possible to obtain propagation times that are perfectly equal whatever the active input of the tree or the edge to be propagation times that are perfectly equal whatever the active input of the tree or the edge to be propagated may be.
Abstract:
The delay device 10 includes an ECL gate 11, the current source 16 and two resistive load elements 14, 15 of which are associated with an adjusting circuit 23 producing an adjusting voltage Vd, to cause the polarization current of the current source to vary hyperbolically, and a voltage Vh for keeping constant the voltage at the collectors of the transistors 12 and 13 of the gate 11. The delay device 10 causes the delays between the input signals IN, IN* and output signals OUT, OUT* to vary linearly. The invention is applicable in particular to systems for the transmission of digital data at a very high rate, of more than 1 gigabit per second, for example.
Abstract:
The invention relates to an integrated circuit including impedances having precise values. To compensate for process variations and drift in impedances, the circuit includes automatic control means (3) to adjust the value of impedances (R) to a value that is a function of that of a reference impedance (Rc) external to the integrated circuit.
Abstract:
Transceiver for transmission over serial bi-directional links having a bi-directional amplifier including an impedance (R) for adaptation to the line and connected to it, a generator (G1) commanded for transmission and supplying the adaptation impedance (R) and the line in parallel, detection device (G2, r) for furnishing a measurement signal (V) representative of either the current circulating in the adaptation impedance (R) when the generator (G1) is active, or the sum of the current in the adaptation impedance (R) and a compensation value when the first generator (G1) is not active. The compensation value is determined so as to make the measurement signal (V) independent of the transmission state of the transceiver.