Abstract:
In a feed-forward, error-correcting system in accordance with the present disclosure, the error signal is formed by comparing the modulation component of the signal before and after signal processing. The error signal is then used to modulate the main signal so as to reduce the modulation error components introduced by the signal processing circuits.
Abstract:
This application described predistortion and postdistortion compensation arrangements wherein compensation is restricted to the nonlinear portion of the transfer characteristic of the network to be linearized. Accordingly, the compensating signal components employed correspond solely to the distortion components of the transfer characteristic. To avoid dispersion effects, the dynamic characteristics of the compensating networks and the network to be linearized are substantially independent of time.
Abstract:
This application discloses a phase modulator comprising a plurality of phase shifters whose output are coupled to a frequency mixer. Carrier signals at different frequencies are applied to the phase shifters along with modulating signals derived from a common source. The resulting phase modulation impressed upon the output signal extracted from the mixer is related to the phases of the input signals to the mixer in the same way as the frequency of the output signal is related to the frequencies of the several input signals. This technique is used to synthesize specific phase functions. In particular, an arcsine function is generated using two varactor diode phase shifters.
Abstract:
A cascade of two identical quadrature hybrid couplers, whose coupling coefficients vary as a function of frequency, are converted to an all-pass network by the inclusion of a 180* phase shifter in one of the two interconnecting wavepaths. Recognizing that the incident signal is coupled primarily to one of the interconnecting wavepaths at the higher frequencies, and to the other wavepath at the lower frequencies, a phase shifter of limited bandwidth, placed in the appropriate wavepath, provides all-pass characteristics over a band of interest which is much broader than that of the phase shifter. This technique is also employed to obtain broadband 180* phase shifters and transformers. By a boot-strapping technique, the band of interest can be further extended.
Abstract:
A frequency steering network, comprising an array of reactive couplers, is described. By suitable selection of the coupler parameters, and the circuits connected thereto, the network can be used to provide a broadband resistance having a prescribed resistance-frequency characteristic; to suppress spurious oscillations in the bias circuit of certain types of oscillators and amplifiers; and as a conventional multiplexer and demultiplexer.
Abstract:
It often occurs that the gain characteristic of an amplifier that is frequency-shaped to correspond to some particular equalization function, differs materially, at the lower frequencies, from the loss characteristic sought to be equalized. The task of matching these two characteristics over a band of interest is shown to be eased by cascading a pedestal amplifying stage and a frequency-shaped amplifying stage and partitioning the overall amplifier gain between the pedestal amplifying stage and the frequency-shaped amplifying stage.
Abstract:
A new class of quadrature hybrid coupler is disclosed comprising a pair of baluns and a pair of symmetrical dual networks made up of simple, reactive elements. One conductor of each balun is connected in parallel with one of the networks and grounded at one end. The other network is connected between the other ends of the two other balun conductors. The four ends of the two other balun conductors constitute the four coupler ports. The two networks are fully defined to produce a quadrature coupler having an arbitrary power division character as a function of frequency.
Abstract:
The notion that an active element, such as a transistor, has unique input and output ports is abandoned in favor of a less restrictive view which examines ''''activity'''' with respect to all ports. More specifically, the eigenstates of an activity matrix which characterizes the active element are defined, and all the ports of the active element simultaneously energized in that state which provides a net gain. The energy scattered from the respective ports is then combined at a common output terminal. Net gain is obtained when the combined output power is greater than the incident power. This gain, however small, is then built up to any specified level by means of an unconditionally stable, positive feedback circuit arrangement. It is an advantage of this approach that the activity defined by the eigenstates is independent of how deeply this activity is embedded within the parasitics of the active element. No special circuitry is required to extract it. In addition, the eigenstates serve as a necessary and sufficient basis to determine the possibility of net gain for any active device.
Abstract:
This application describes a conductance-loaded transmission line ''''resonator.'''' The ''''resonator'''' comprises a reactively terminated transmission line along which there are connected a plurality of shunt conductances. The termination and the conductances are spaced such that at band-center, each conductance is in the region of a voltage null. The use of such a conductance-loaded transmission line as the resonator of an oscillator, and as the frequency selective portion of a filter are described.
Abstract:
The specification describes processes using ion implantation for preparing silicon diode array targets for video camera tubes. Bulk silicon prepared in the conventional way has sufficient nonuniformity over the target area to produce contrast patterns in the video output. This effect can be eliminated by initially preparing high resistivity bulk material and implanting the bulk impurities to obtain the desired bulk resistivity. Advantageous procedures for implanting the diodes are also described.