摘要:
A charge control circuit for bidirectionally transferring metered amounts of charge, selectively, through a transfer channel of a four gate electrode charge coupled device (CCD) is disclosed. The bidirectional charge control circuit is used primarily to increment and decrement metered amounts of charge respectively to and from a charge storage medium. More specifically, five electrical signals are generated to have varying potentials in accordance with predetermined time sequences. These signals are applied to the four gate electrode CCD in a selected one of two states to either increment or decrement a metered amount of charge therethrough to or from the charge storage medium respectively, in a predetermined number of five segments. One of the generated signals governs the metering of charge for each increment or decrement operation.
摘要:
A coherent sampled CMOS readout circuit and signal processor coupled to a CCD shift register operated by a two-phase minority carrier transfer clock system. The invention comprises a multiplex MIS switch, a reverse biased collection diode, an N channel MOSFET reset switch, a P channel MOSFET electrometer amplifier, and a sample and hold circuit, the configuration having four distinct operational timing subintervals within a clock period wherein the charge is shifted from one shift register bit to another and finally to the output bit. This removes the Nyquist noise associated with the reset switch, suppresses switching transients and 1/f surface noise to thereby improve the signal to noise ratio, i.e., dynamic range, for a CCD array and readout system.
摘要:
An adaptive analog processor incorporating a analog shift register having a plurality of taps, multipliers at each tap for multiplying the tap value times a weight value, a first adder for summing the output of the multipliers, a second adder for subtracting the output of the adder from a second analog signal, means for incrementing the weights in response to the magnitude and polarity of the error signal and the polarity of the data signal. The invention overcomes the problem of building monolithic multitap adaptive filters utilizing the clipped-data least mean square error algorithm.
摘要:
Extended correlated double sampling (ECDS) for charge transfer devices (CTD) corrects for errors arising in components of the CTD system from the input to the output thereof. Sources of error include bias variations and non-uniformity of thresholds and leakage currents. While applicable to any type of CTD system, for a TDI (time delay integration) application, precise error correction is achieved. Alternate signal level samples and reference level samples, the latter preferably AC zero, are propagated down the CTD channel as a related pair. At the CTD output, the signal and reference level samples of each pair are differenced, thereby correcting the resultant output signal for the noted types of errors. ECDS is compatible with CDS as taught in U.S. Pat. No. 3,781,574 and the two may be used jointly. An application of ECDS in the TDI mode for enhancement of signal outputs from a sensor array is disclosed, along with special parallel signal injection structure and operation for the requisite parallel signal injection into the channel, and special techniques of stabilized charged injection (SCI).
摘要:
In a charge transfer device (CTD), such as a charge coupled device (CCD), a gate electrode employed for sensing of the charge packet being transferred, or coupled through the device is clocked during one phase of the four-phase clocking and is permitted to float, i.e., be isolated, during a sensing phase of the four-phase clocking. Since the sensor is a gate electrode rather than a diffusion, it presents no obstruction to the propagation of charge down the channel. Since sensing occurs while the electrode is floating, the sensing or readout function does not have any detrimental effect on the propagation of charge down the channel, i.e., it affords a truly non-destructive readout. During a clocking phase in which charge is isolated under a different gate electrode, an attractive voltage clock pulse is applied to the sensor electrode, rendering it attractive. The sensor electrode is then isolated from the clocking source and, in the appropriate succeeding clocking intervals, the charge advances to the well under the sensor electrode. Sensing of the charge then occurs while the electrode remains in its floating condition. Subsequently, a clock pulse is applied to the sensor electrode rendering it repulsive to advance the charge down the CCD channel. The floating clock sensor electrode of this invention is highly advantageous in any application requiring non-destructive readout; an illustrative configuration for non-destructive parallel output (PO) operation of a CCD shift register is disclosed.
摘要:
An imaging system comprising a multi-channel matrix array of CCD devices wherein a plurality of sensor cells (pixels) in each channel are subdivided and operated in discrete intercoupled groups or subarrays with a readout CCD shift register terminating each end of the channels. Clock voltages are applied to the subarrays and are manipulated to selectively cause charge signal flow in each subarray in either direction independent of the other subarrays. More particularly, the array is divided into six independent subarrays, three on each side of the array, such that each channel common to three subarrays is divided into three sections of three sensor cells each. By selective application of four phase clock voltages, either one, two or all three of the sections cause charge signal flow in one direction, while the remainder cause charge signal flow in the opposite direction. This creates a form of selective electronic exposure control which provides an effective variable time delay and integration of three, six or nine sensor cells or integration stages. The device is constructed on a semiconductor sustrate with a buried channel and is adapted for front surface imaging through transparent doped tin oxide gates.
摘要:
An analog multiplier for multiplying the signals derived from a charge coupled device (CCD) tap includes a balanced multiplier of a first conductivity-type and a buffer of a second conductivity-type coupled between the CCD tap and the balanced multiplier. The multiplier includes first and second transistors, the drains of which are coupled together to form an input. The buffer includes a load transistor coupled to the output of an amplifying transistor. Means are included for coupling the output of the amplifier transistor and the multiplier input.
摘要:
A CCD image sensor has a plurality of elements, each such sensing element includes a doped semiconductor substrate, an insulator layer over the semiconductor substrate, and an electrode on the insulator layer which when potential is applied to the electrode creates a well in the bulk of the substrate which collects charge as a result of a photoelectric process. The insulator layer has a thin portion selected so as to allow excess charge collected in the channel to tunnel through the thin region to the electrode and thereby prevent blooming.
摘要:
A stabilized charge injector for charge coupled devices (CCD) includes a diffusion and two or more gate structures in a CCD channel wherein the diffusion alternately acts as a source and drain of the minority-type signal carriers. D.C. signals are applied to the gates immediately adjacent the diffusion and the next successive adjacent gate to provide a charge injection which is proportional to the difference between the signal voltage applied to the one of the two gates and a DC reference voltage applied to the other thereof. Low noise performance is achieved through utilization of a quasi-static operation in which neither of the aforementioned gates adjacent the diffusion is pulsed. Moreover, the use of a gate injector presents at the input, a true capacitance defined as a function of the gate oxide layer. Hence, the value of capacitance is constant and independent of the signal voltage applied. A stabilized charge injector structure is disclosed providing a large value of capacitance for minimizing noise in the injection operation, and wherein problems otherwise arising out of the large size of the capacitance as to adequate speed of propagation of charges from the capacitance to a CCD charge transfer structure are overcome by special gate electrode structures and pulsing techniques to provide successive pushes of the charge being injected from the gate capacitance into the receiving CCD transfer device. The stabilized charge injector may be used for either serial or parallel injection into a CCD channel and its advantages most fully being realized in the parallel input mode; operating waveforms for the charge injector to provide parallel injection into a CCD channel during each shift cycle thereof and, alternatively, to provide selectively timed parallel charge injection in successive intervals are disclosed.
摘要:
A programmable analog transversal filter is disclosed for processing analog signals and comprising a charge-coupled device (CCD) for receiving a series of discrete analog signals to be delayed by increasing periods and applied to the outputs of the CCD, and a plurality of MNOS memory devices coupled to the taps of the CCD and programmed so that the output of a CCD tap is multiplied by a particular factor. In turn, the outputs of the MNOS memory devices are summed to provide an output signal ##EQU1## where W.sub.k is the weighting factor associated the k.sup.th MNOS memory device. The weighting factors are set into the system by varying the threshold voltage of the corresponding MNOS device. Positive and negative weighting factors are implemented by using first and second MNOS memory elements for each tap of the CCD, whereby depending upon the program incorporated into the system, one of the first and second MNOS memory devices is programmed to give either a positive weighting factor and the other MNOS memory device a negative weighting factor. Further, a reiterative method of setting the weights into the MNOS memory device is used to compare the system output indicative of the weighting factor as set into the MNOS memory devices, with the desired weighting factor as stored in a suitable storage memory such as a ROM, whereby a correction signal is developed to adjust the threshold voltage V.sub.Th of the MNOS memory device in accordance with the stored weighting factor. In one illustrative embodiment, the weighting factors are set in accordance with sinusoidal signals, whereby the system performs a filtering function to provide an output upon receipt of an input signal of desired frequency. In addition, the MNOS devices are reprogrammable, thus permitting a single such system to be used in many different applications. In this regard, this system is particularly adapted for complex signal processing including filtering, generating desired functions, synthetic aperture radar signal processing and target identification processing.