Showing papers on "Total harmonic distortion published in 1974"

Fast amplitude stabilization of an RC oscillator

Abstract: A technique is proposed for stabilizing the output amplitude of a variable-frequency RC sine-wave oscillator. Amplitude settling time is reduced by converting amplitude to a d.c. voltage having only a small ripple content, which requires little filtering. A relationship between amplitude transient response and harmonic distortion is demonstrated, and the results are compared to those obtained by more conventional methods.

A harmonic oscillator with low harmonic distortion and stable amplitude

Abstract: A generator of the harmonic signal is described for frequencies in the acoustic region with the reference stabilized amplitude, linear frequency scale and total harmonic distortion below 2 × 10−3 The signal is produced as the solution of the corresponding differential equation where the constant amplitude is maintained by periodic control of the first derivative value [xdot](t) at the moments when x(t) crosses zero and has a positive slope

Waveform shaping techniques for the design of signal sources

Abstract: A new circuit technique is described for the generation of a sinusoid from a triangle waveform based on the addition of suitably proportioned current trapezoids. Undesirable operating characteristics, particularly peak and crossover distortion associated with previously reported methods, are reduced to more tolerable levels in a fully temperature-compensated design. An optimum breakpoint and distortion analysis is developed for establishing the design method and estimating the performance of the circuit. Measurements made on the prototypes indicate that a total harmonic distortion of better than 0.2% is readily attainable, whilst the non-saturating transistor circuit design offers considerable potential at high frequencies. The technique is readily amenable to the thick-film process with the modest spread of resistor values, and the absence of any tedious setting-up procedure makes the circuit particularly attractive to the user.

Instrument for measuring harmonic distortion in telephone transmission

Abstract: There is disclosed an instrument for measuring and displaying the harmonic distortion introduced during telephone line transmission. A frequency phase lock circuit is employed to generate disturbance-free in-phase and quadrature signals of a received test tone, the disturbancefree generated tones being different from the transmitted test tone as a result of possible frequency shift along the transmission channel and phase shifts in the terminal equipment at both ends. The frequency of each of the in-phase and quadrature signals is multiplied by the harmonic factor of interest (e.g., two). Each of the frequency-multiplied signals is then multiplied by the received test tone, and the two resultant signals, after low-pass filtering, are applied to the vertical and horizontal deflection plates of an oscilloscope to form a display of the type disclosed in my copending application Serial No. 455,197. The display, in addition to reflecting a measurement of the frequency shift along the channel, also provides separate indications of the degree of harmonic distortion which occurs both ahead of the frequency shift (in the send terminal) and after the frequency shift (in the receive terminal).

New field effect devices with linear V-I characteristics

Abstract: A new field effect device which shows the linear relation between the drain voltage(V) and current(l) in the operational range of drain voltage more than ±10 volts has been studied and developed. This device has the special gate structure composed of the semi-insulated polycrystalline silicon resistive layer. Typical electrical characteristics of this device applied to the L-type gain control circuits were measured as follows; 1) the extremely low harmonic distortion less than 0.02 % at 6 db attenuation for the in-put signal level of 0 dbm at 1 KHz, 2) the large attenuation more than 80 db for the large in-put signal level of 20 dbm. This device will be an useful tool to expand the dynamic range and the improvement of circuit characteristics in the gain control circuits and will also be applied for new multi-channel analog switching devices without the tracking error.

Circuit to reduce harmonic distortion in a triangular wave-form function generator

Abstract: A device is disclosed for generating a triangular wave form for use in an electronic function generator. The device employs a level detector which produces a square wave output to drive a triangular function generator in a loop arrangement. Amplitude symmetry of the triangular wave is maintained by sensing the average value and comparing it with a reference level to generate an error signal which in turn serves as a reference input to the level detector. The output of the level detector is therefore corrected to cancel drifts in the average or base line value of the triangular wave form. Time symmetry, or symmetry of the positive and negative slopes of the triangle is maintained by means of a feedback loop utilizing a stable current source. The time symmetry of the square wave is the same as that of the triangle. The square wave is sensed and serves to switch on and off the stable current source. By integrating the current from the current source a voltage is obtained which is proportional to time asymmetries in the square wave. An error signal derived from the integrated current is used in the triangle generator to control either the positive or negative slope of the wave form. A triangular wave form is therefore generated which has both stable amplitude symmetry and time symmetry.

Dynamic f.m.-discriminator distortion

Abstract: The demodulation of an f.m. signal introduces both static and dynamic distortion. This letter presents a 1st-order approximation to the latter, and determines the spectrum of the intermodulation resulting from both effects. This analysis is based on the van der Pol-Stumpers expansion of a filter's response to an f.m. wave.

Harmonic distortion of the Darlington composite transistor

Abstract: Based on the current-voltage transfer characteristic, equations were derived relating this distortion levels, the operating conditions mid the characteristic parameters of a transistor amplifier, The characteristic of the Darlington composite transistor was determined experimentally, and its harmonic distortion was analysed and compared with its component, transistors, Compensation of harmonic distortion by load and source resistances was discussed.

Bandpass Microwave Electron-Bombarded Semiconductor Amplifiers

Abstract: This paper introduces a new type of microwave amplifier which employs as its active element electron-bombarded semiconductor diodes. This amplifier is capable of achieving both high peak and high average powers. Useful characteristics include its broad bandwidth (several GHz are possible), high efficiency (in the 50 to 60 percent range), and very low harmonic distortion. These characteristics make this amplifier extremely attractive for use in a variety of communications, RADAR, and laboratory test applications.

A Design Basis for Ferro-Resonant Parallel Inverters with Silicon Controlled Rectifiers

Abstract: The paper describes the operation and design basis of medium power S. C. R. parallel inverter in which magnetic ferro-resonance has been utilised to achieve some desirable properties. Example of a specific system which consists of a 500 VA parallel inverter providing 220V, 50 Hz a.c. from a 48 volts d.c. input using ferro-resonant transformer and a constant frequency trigger circuit with crystal control and associated transistorised scale-down circuit has been discussed. The main advantages of such an inverter are economy in components and cost, inherent output voltage stabilization within ± 10% for variation in the input d.c. voltage as well as load changes, short circuit/overload protection, sinewave output with harmonic distortion less than 5% without using any additional filter and frequency stabilization accuracy of about 0.5 parts per million. The applications of such an inverter are in standby a.c. power supply for computers, frequency stabilizer/master clock control system for electric clocks, a.c...