In this paper, the main theory of DDS and the working principles of AD9850 are described at first, and then the generating circuit of a pulsed ultrasonic scanning waveform based on two AD9850s is introduced.
The hardware system is mainly composed of sine wave source generating circuit, data acquisition and conversion circuit, TMS320F240 and its peripheral circuit, external memory circuit, 4x4 matrix keyboard circuit, LCD and serial communication circuit.
The input isde is a PFC circuit with 400V DC voltage, with a full-bridge MOSFET inverter circuit, at the fixed-frequency PWM generating circuit and IR2110 driving circuit, the input DC voltage is changed to high frequency AC voltage, by only one resonant inductor, the MOSFET can achieve the zero voltage turn-on, this greatly decreases the switching lose and the switching noise.
Secondly, basing on analysis of Direct Digital Frequency Synthesis (DDS)’s principle, structure and its optimization, this paper designs a low power consumption, high stability DDS generating circuit to generate a sine wave as the driving source for inductive displacement transducer.
The Large Scale Integration of "Chess Pattern Generating Circuit"with the ispLSI1016 Chip
According to the characteristic of the semi-conductor gas-sensor,this system heats the gas-sensor array through multi-wave generating circuit,making it possible to detect some essential characteristics that the usual method can not do. The system has provided a good platform for testing the property of multi-sensor.
The SPWM ware pulse generating circuit of inverter adopt SA4828 and AT89C51, In this paper, based on research of tradition PI regulator and synchronous PI regulator, a new regulator, P+Resonant stationary regulator, is adopted to the control system design of inverter.
The flexibility of using real-time pulse generating circuit which is composed of programmable counter 8253 in computer controlled system is introduced. The frequency and quantity of real-time pulse signal are achieved by circuit and controlled by program.
1.Demonstrating the working process of the high speed data generator and the functions of its circuits, and giving the principle of the data loading circuit, generating circuit of high speed data and output control.
This paper investigats steep wave impulse volt-age testing techniques of HV line insulator to rneet theneeds of DL/T 557-94 standard ar1d insulator voltage-timecharacteristics test within 100～ 400 ns. Study rcsults ofvoltage generating circuit parameters, resistive voltage di-vider structure and selected impulse oscilloscope are pre-sented.
The purpose of this article is to discuss a multiplier using step recovery diode. The theory of operation of highly efficient harmonic generating circuits is described, with experimental results and practical circuitry in the frequency range: 140 MHz to 1400 MHz.
Servo signals writing and generating system for the 200MB magnetic disk servo track writer is presented in this paper.The functions and features of this system,as well as the generating circuits of the benchmark,index and 6720 synchronous signals,and the servo signals write/read circuits are described.
Points out the inadequacy of the sine PWM (pulsewidth modulation)signal and general PWM signal for CVCF (constant voltage & constant frequency)inverters and proposes the PWM Step-wave Signal as a new scheme.Experimental and theoretical result showes that the new signal has a wide range of voltage regulation,a high voltage of first harmonic and a low voltage of other harmonics.The generating circuits for the new signal are given.