Abstract:
This analog-ditigal coder determines the coefficients a.sub.o . . . a.sub.n in two stages:during the first stage, the generator processes voltages V.sub.R and V.sub.Ri with i=1 to k-1;during the second stage, the generator processes the voltages V.sub.R and V.sub.Ri with i=1 to n-k.A capacitive voltage divider (2.sup.k C, C) preceded by two sample and hold means (S.sub.3, C.sub.3, S.sub.4, C.sub.4) assures the division by 2.sup.k of the voltages processed during the second stage and their summation with the final voltage V.sub.R(k-1) produced during the first stage.
Abstract:
In a device for current-reading of a quantity of electric charges, the control circuit for the first and second MOS transistors receives a constant potential and comprises:a third transistor, the drain and gate of which are connected to the constant potential and the source of which is connected to the drain and to the gate of the second transistor;a second capacitor connected through one of its terminals to the nodal point of the second and the third transistor.The device is employed for reading quantities of charges which arrive under the storage electrodes of charge-transfer filters.
Abstract:
An analog device for reading a quantity of electric charge, for example, in a transversal charge transfer filter. The device includes a capacitor and two MOS transistors which are connected in series to the point in the filter where the charge is to be read. The capacitor is connected to the common point of the two transistors which are controlled in phase opposition to insure charging of the capacitor. The capacitor maintains a potential at the charge reading point constant. Any variation in the quantity of charge under an electrode is converted into a variation of potential at the common point and this forms the read signal which is detected by means of a third MOS transistor.
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. In other words, when the input signal contains a component of frequency Fs close to the sampling frequency Fe, by a process of frequency mixing, two parasitic signals at the image frequencies Fe + Fs and Fe - Fs are created. Since we are concerned with a low-pass filter, the top image frequency (Fe + Fs) is automatically eliminated but the bottom image frequency (Fe - Fs) can be transmitted by the filter and appear in the output signal if the condition Fe - Fs
Abstract:
The switched-capacitance amplifier comprises n capacitors C.sub.11 to C.sub.1n which are periodically switched in parallel and in series, the n parallel-switched capacitors being charged simultaneously by the same voltage V.sub.E. An amplified voltage n.times.V.sub.E is obtained between the end terminals A and B of the n series-switched capacitors. Periodic switching of the n capacitors in parallel and in series is performed by means of MOS transistors T.sub.11 to T.sub.1(2n-1) and T.sub.21 to T.sub.2(n-1) which operate in the switching mode. The n capacitors and the MOS transistors are integrated on the same semiconductor substrate.
Abstract:
A device for reading a quantity of electric charges arriving at a point B. Two MOS transistors Q2 and Q3 are connected in series and with one terminal to point B. A capacitor C.sub.A is connected to a common point A of the two transistors. A transistor control circuit charges the capacitor C.sub.A from a low potential V.sub.DD. The capacitor C.sub.A and the transistors Q2 and Q3 maintain a constant potential at the point B at the time of charge inflow. This results is a variation of potential at the common point A in accordance with the incoming charges at B. Thus, the variations of potential at point A is a measure of the charges arriving at point B.
Abstract:
Successive two-trip traversals of charges between gates G.sub.0 and G.sub.2 make it possible to obtain beneath gates G.sub.1 and G.sub.2 quantities of charges equal to Q.sub.R, Q.sub.R /2, Q.sub.R /2.sup.2 . . . Q.sub.R /2.sup.i. A readout device for reading charges and connected to gates G.sub.2 and G.sub.4 generates voltages V.sub.R and V.sub.Ri =a.sub.0 .multidot.V.sub.R +a.sub.1 .multidot.V.sub.R /2+ . . . +a.sub.i-1 .multidot.V.sub.R /2.sup.i-1 +V.sub.R /2.sup.i which are compared with a voltage sample V.sub.x to be coded in order to determine by successive approximations the coefficients a.sub.0 . . . a.sub.n which are equal to 0 or to 1 such that V.sub.x =a.sub.0 .multidot.V.sub.R +a.sub.1 .multidot.V.sub.R /2+ . . . +a.sub.n .multidot.V.sub.R /2.sup.n. Depending on the value of a.sub.i, each quantity of charges Q.sub.R /2.sup.i stored beneath gate G.sub.1 is removed beneath diode D.sub.e or stored beneath gate G.sub.3 and then transferred beneath gate G.sub.4.