Abstract: The input voltage (V.sub.e) of the device is constituted by the superposition of a direct voltage (V.sub.0) and a time-varying sampled voltage (v.sub.e). Subtraction means comprising storage and transfer electrodes, and diodes, establish the difference between the quantity of charges which is double the quantity corresponding to the direct voltage (that is, 2Q.sub.moy) and the quantity of charges corresponding to each sample of the variable voltage superposed on the direct voltage (that is, Q.sub.moy .+-.q.sub.e).

Abstract: The storage electrodes are electrically connected at a point. A reference charge quantity is stored beneath the first storage electrode when the point is at a constant potential and before charges pass beneath the second storage electrode. When a charge quantity arrives beneath the second storage electrode and when the point is floating, the surface potential beneath the first storage electrode is maintained constant and a charge quantity is transferred from the first storage electrode to a third storage electrode.

Abstract: The invention relates to a device for reading a quantity of electric charges then injecting in a charge-transfer device a quantity of charges which depends on the quantity previously read. This device comprises a reading grid connected to the source of an MOS charge-injection transistor operating in saturation and formed from two diodes and a control grid.

Abstract: The filter has p stages, p being the number of bits on which are expressed the digital filtering coefficients. Each of the stages has a charge transfer shift register, called the signal register, receiving the analog signal E(t) to be filtered and a charge transfer shift register, called the coefficient register, receiving the M bits of the same weight of the M filtering coefficients. The filter also has an operator which multiplies the signal E(t) by each of the M filtering coefficients and then summates these various products to supply the output signal S(t) of the filter.

Abstract: The process more particularly comprises introducing beneath the final storage capacitor C.sub.6 a quantity of charges equal to that located there during the processing of the preceding sample of the input signal, prior to the beginning of charge transfer from said capacitors to the means which convert the charges into a voltage, and distributing the charges between said capacitor and the preceding capacitor as a function of the capacitance values. The switched capacitor filter more particularly comprises, when it is looped, a circuit R permitting the application to the looping capacitor C.sub.4 of a voltage V.sub.g +.DELTA.V.sub.s, while the foils of the other storage capacitors of the filter are connected to the voltage V.sub.g.

Abstract: One storage electrode of the filter out of two is cut into two parts. The weighting coefficients are elaborated by reading means connected to a part of each cut storage electrode which read negatively the charges leaving a so-called negative cut storage electrode and positively the charges arriving under the next so-called positive cut storage electrode.

Abstract: An input stage for a transversal charge transfer filter, which suppresses parasitic image frequencies. It comprises two parallel channels to which the input signal is applied simultaneously. Sampling of the signal is performed in each channel with a periodicity Te, and a relative phase-shift of Te/2. The two samples are then added in order to eliminate components having periodicities in the neighborhood of Te.The present invention relates to low-pass filters using the phenomenon of electrical charge transfer occurring in a semiconductor. It relates more particularly to an input stage for this kind of CTD (Charge Transfer Device) filter, which attenuates parasitic frequencies.The design of CTD low-pass filters, often referred to as transversal filters, poses a classic problem due to the fact that the input stage is a sampling stage.