Abstract: A wireless communications device includes an amplifier module configured to amplify a signal. The amplifier module includes a serial arrangement of amplifiers. Each of the amplifiers are designed to operate with increased efficiency for different power level ranges. The amplifiers are connectable via controllable switches. A controller, in communication with the controllable switches, selectively connects the amplifiers to increase the efficiency of the amplifier module.

Abstract: A digital-to-analog converter (DAC) including an array of switched input capacitors which store samples of charge proportional to a digital input signal, and an analog output circuit which integrates the samples of charge to generate an output analog signal that is proportional to said digital input signal. The capacitors store a binary representation of the digital input signal. The output circuit includes a zeroth order sample-and-hold circuit having first and second stages with respective first and second operational amplifiers. The first and second stages are cascaded together during a sample phase so that the analog output signal is stored in a capacitor in a feedback path between the output of the second stage and the input of the first stage, and are disconnected from one another during a hold phase so that the first stage is auto-zeroed and the second stage holds the analog output signal as a continuous time output.

Abstract: A method and circuit for preamplifying reception signals for a radio station. A first preamplifier is connected between an antenna unit and to the radio station. A second preamplifier is provided in the radio station, the second preamplifier being bridged by a bridge line. A switch can selectively switch the radio signals through either the second preamplier or the bridge line, under control of a controller.

Abstract: A plurality of amplifiers are connected in cascade to form an in-line predistortion circuit. The amplifiers are unbalanced in that each amplifier stage in the circuit has two DC voltage rails which are independently controlled to provide different, i.e. offset, DC voltage levels to the unbalanced amplifiers. This unbalance in the amplifiers generates predistortion in a signal which can be used to cancel the inherent distortion caused by a non-linear device which subsequently processes or transmits the predistorted signal. Control of the DC voltage offset in at least one of the amplifier stages is necessary to match the predistortion to the inherent distortion being corrected. A tilt circuit can be used in cascade with the plurality of amplifiers (in front of the RF amplifiers) to compensate the amplitude change caused by the unbalanced RF amplifiers. Either side of the DC voltage can be changed in order to correct for either sublinear or superlinear laser diode curves.

Abstract: A hybrid thermionic valve and solid state audio amplifier. A complete tube amplifier is scaled to produce a relatively low power yet also retain its small and large signal distortion characteristics. The output of the scaled amplifier is amplified by a relatively linear solid state amplifier. In one embodiment of the invention, a plurality of tube amplifiers are coupled in parallel and input to a mixing circuit for selectably mixing the outputs of the tube amplifiers and providing the mixed outputs to the solid state amplifier.

Abstract: An amplifier (104) for a dual band device includes multiple amplifier stages coupled between an input (103) and output (105). The amplifier stages include a first amplifier stage (200) having a first amplifier (206), a second amplifier stage (202) having a second amplifier, and a third amplifier stage (204) having a third amplifier (210). A first bypass (218) in said first amplifier stage provides a bypass for signals in a first frequency band. A second bypass (250) is provided in the third amplifier stage, the second bypass to provide for signals in a second frequency band a signal path that bypasses the third amplifier. Signals in the first and second frequency bands are amplified by the second amplifier.

Abstract: In a direct coupled type vacuum tube amplifying circuit, to stabilize the operation and simplify the feedback loop, a plate power source EB5 is connected to a plate of a vacuum tube V5 of a first stage through a constant current source 1. A grid of a vacuum tube V6 of a next stage is connected to the plate of the vacuum tube V5 through a first resistance R3. A second resistance R4 is connected between the grid and the cathode of the vacuum tube V6. A negative power source EC6 is connected to the resistance R4 through a constant current source 2. In this constitution, the grid bias voltage of the second vacuum tube V6 is defined by the voltage drop of the second resistance R4.

Abstract: The disclosure relates to the linear power amplification, in a single channel, of a composite signal formed by two independent signals. In a single channel formed by correction means followed by a linear preamplifier followed by a saturated amplifier, the filtering and symmetry effect produced, both in the correction means and in the saturated amplifier, is advantageously used to compensate for clipping of the composite signal due to the amplifier. This makes it possible to obtain an undistorted output signal whose amplitude exceeds the level of saturation of the saturated amplifier. The compensation makes it necessary for the transfer characteristic of the correction means to have a given slope between two points beyond which the saturation appears in the saturated amplifier and a slope that is substantially thrice the given slope on each side of these two points.

Abstract: A current amplifier including two stages. A first stage is formed by a primary operational amplifier (IC1) connected in a virtual earth feedback configuration and having a feedback loop formed by a resistor (R1) and capacitor (C1) connected in parallel so that the primary operational amplifier has a frequency response up to a predetermined frequency and thereafter the frequency response rolls off at a predetermined rate. A second stage including another operational amplifier (IC2) connected in a virtual earth or non-inverting feedback configuration having a frequency characteristic chosen to provide in combination with the frequency characteristic of the primary amplifier a desired operating range for the amplifier.

Abstract: A low pass-filter for low frequency signals having first portions situated above on one side and second portions situated on the other side of an average value.The filter comprises at least two integrators, each comprising a capacitor, included between the input and the output of a voltage-inverting amplifier, and a current source connected to said output, and three threshold comparators, of which the first one is connected to the input of the filter, of which the second one is included after the first integrator, and of which the third one is connected to the output of the filter.The arrangement is used in logic circuitry.