Bell Telephone Laboratories

Robert Henry Walden

Robert H Krambeck

Carlo Heinrich Sequin

Robert Joseph Strain

Charge transfer devices which permit movement of charge carriers in two noncollinear directions in the surface plane of the device. A network of electrodes in two levels of metallization is combined with an appropriate doping of the storage medium to define the charge transfer paths. The direction of charge transfer is determined by an appropriate pulsing of the network which may take the form of different driving sequences of a number of phases in various embodiments. This concept may be used for both charge coupled and bucket brigade devices.

Two-dimensional transfer in charge transfer device

A two-phase charge transfer binary counter capable of counting the number of signal pulses in a particular time interval is described. The counter includes a charge storage medium in which is formed at least one charge storage 'Q-cell' adapted to quantize each signal pulse into a charge packet. In tandem with the Q-cells are a plurality of one-bit shift registers each of which, except the last, comprises first and second charge storage cells connected in series. Adjacent cells of the same shift register are separated from one another by a threshold potential barrier of magnitude V.sub.T which permits only partial charge transfer thereacross. In contrast, adjacent cells of consecutive shift registers are separated from one another by a smaller transfer potential barrier of magnitude V.sub.B which permits virtually complete charge transfer thereacross. A feedback path is established between adjacent cells of the same shift register in order to clear residual charge from the first cell in response to charge transferred over its threshold barrier. At the end of the time interval, however, charge transfer ceases and the charge packets residing in the first cell of each shift register are the binary equivalent to the number of signal pulses in the time interval.

Charge transfer binary counter

A charge transfer analog signal filter is described in which a plurality of charge storage cells are connected in series to form a delay line having a time delay T between its input and output cells. In a feed-forward rejection filter the analog signal is applied to the input cell through a cell of area A.sub.1 and to the output cell through another cell of area A.sub.2. The transfer function of the rejection filter is ##EQU1## In a feedback bandpass filter the analog signal is applied to the input cell through a cell of area A.sub.1, and the output cell is coupled to the input cell through the series combination of an analog inverter and another cell of area A.sub.2. The transfer function of the bandpass filter is ##EQU2##

Charge transfer delay line filters

In charge transfer apparatus, an analog inverter comprises a charge storage medium to which are applied varying voltages through a plurality of electrodes, illustratively: a source electrode, a reference electrode and a collector electrode arranged in tandem. Between the source and reference electrodes there is a first control electrode and, in one embodiment, between the reference and collector electrodes there is a second control electrode and a signal electrode. With the electrical signal to be inverted connected to the signal electrode, analog inversion, a form of complementing function, occurs as follows: (1) during the first phase of the clock cycle, a voltage is applied to the first control electrode effective to cause a fixed amount of charge to be transferred from the source to a reference potential well established under the reference electrode; (2) during the second phase of the clock cycle, a voltage is applied to the second control electrode effective to increase the surface potential thereunder and to permit charge to be transferred into a potential well under the collector electrode; this charge establishes a new surface potential which, apart from an additive constant is equal to the inverted signal voltage. In other embodiments in which the analog signal is of a self-strobing type (e.g., the output of a C4D or BB) the second control electrode is not required.

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New Providence, NJ, United States of America

Robert Henry Walden