Robert Boschgmbh

Klaus Lehmann

Dieter Poetsch

Karl-Heinz Muller

Michael Hausdorfer

Friedrich Zimmermann

Klaus D M/u/ Ller

Hans-W Zappen

A resonant circuit which includes the input capacitance of the clock pulse inputs of a shift register (10) is pulsed by a sinusoidal wave at voltage peaks of the wave by an oscillator delivering barely enough energy to overcome the damping of the resonant circuit. The oscillator may be crystal controlled and, instead of having a single ended output for delivering energy only on peaks of one polarity, may be in push-pull form reinforcing oscillation peaks of both polarities. This circuit is easily combined with arrangements for switching oscillator frequency from one value to another and/or arrangements for interrupting the clock pulse output for timed intervals after each loading or unloading of the shift register. The loss power dissipation is reduced to about 6% of the loss power dissipation of a square pulse drive for the clocking of the same shift register. The low loss drive for shift register advancement is applicable to a variety of analog stepped storage and delay devices, such as charge coupled devices and 'bucket brigade' devices.

System for shift register clocking of analog storage cells

To eliminate or suppress amplifier noise in amplifiers (6, 7) connected to a semiconductor light sensor, for example of a charge coupled type, in which the noise introduced by the amplifiers has a frequency spectrum which is low with respect to the clock frequency of operation of the sensor, the minimum value signal from the light sensor, as amplified, is determined; the maximum value of the signal, as amplified, is determined; and a reference is derived based on the minimum value, for example by clamping the minimum value, or utilizing the minimum value as a dynamic reference for subtraction from the maximum value, to thereby eliminate the effect of low-frequency shift of signals due to low-frequency noise of the amplifiers; various circuits may be used, such as clamping circuits (FIG. 3), threshold or non-additive mixing circuits (FIGS. 4, 5) coupled to a subtraction stage (24), band-pass filtering and envelope demodulation (FIG. 6: 28, 29, 30) or synchronous demodulation (FIG. 7: 34, 35) using the scanning clock frequency (36, 37) for synchronous demodulation, coupled with frequency limiting the output to, for example, one-half clock frequency in a low-pass filter (39).

Method and system to reduce low-frequency noise in semiconductor sensors

For reduction of the relative noise amplitude a modulator or chopper stage is provided in front of the input of a video preamplifier and at the preamplifier output balanced demodulators are provided with a subtraction circuit combining their outputs. Preferably the carrier wave used for chopping or modulation is applied to the demodulators for synchronous demodulation, with a phase shifter if necessary in the carrier supplied to the demodulators for compensation of the signal propogation time through the preamplifier.

Low-noise video preamplifier

To provide for essentially inertia-free amplitude adjustment of video signals, an electrical circuit is provided with a field effect transistor having variable source-drain resistance. The circuit includes two junction transistors which are connected to the gate electrode of the field effect transistor and either to the source electrode or the drain electrode. One such transistor is connected as an impedance converter, and the other in grounded base configuration. By means of a variable voltage applied to a resistor is connected to the gate electrode of the field effect transistor, source-drain resistance of the field effect transistor can be varied essentially linearly.

Broadband circuit with rapidly variable resistor

A diode, of which the nonlinear characteristic is utilized for correcting the gradation characteristic of a video signal, has one of its electrodes connected to the output of the correction circuit, and has a voltage applied to its other electrode which is derived from the output voltage by inversion, amplification and integration during the blanking interval. Thus, in every blanking interval, the steady potential terminal of the diode is clamped to the desired black picture level for automatically holding constant the working region of the diode. An operational transconductance amplifier charges a capacitor, the voltage of which is applied to the diode through an impedance converter.

Circuit for modifying the gradation of pictures produced by video signals

Signals are picked off from semiconductor image or line sensors in clock pulse intervals corresponding to successive picture elements (in order to improve the signal-to-noise ratio, an amplifier with a high input resistance is used, the charge of the output capacitance of the sensor produced at the instant of the last clock pulse is substantially maintained during a first part of the clock interval, so that the full amplitude can be picked off after transients have died down and thereafter, in a second part of the clock pulse interval, the charge is drained away.

Growing community of inventors

Muhltal, Germany

Klaus Lehmann