摘要:

The design procedures necessary for maximising dynamic range of cascade, f.l.f., i.f.l.f. and m.l.f. active-filter topologies, are presented and equations are derived for computing the total output-noise voltage contributed by internal-noise sources. Further, it is shown that the equivalent input noise of a second-order biquad section is dependent not only on circuit configuration and pole-Q, but in some cases also on the section gain. As a result, the total output noise of high-order filters may or may not be a function of the overall filter gain, depending on whether the equivalent input noise of the second-order section used as building block is not or is, respectively, a function of section gain. A comparison of the different topologies indicates that in addition to the advantage of being easy to design, the f.l.f. filter is the only topology whose output noise can remain constant regardless of the overall filter gain and the type of second-order used.

DOI:10.1049/ip-g-1.1980.0020

出版商:IEE    

年代:1980

数据来源: IET

摘要:

High-frequency power packs with sinusoidal output are often required in different fields of scientific investigation. The conventional designs of such sources are associated with some critical and complex problems. The authors devised a simple circuit using a solid-state power-transistor switching system actuating a pulse transformer as its load where the equivalent inductance and distributed winding capacitance play the critical role of wave generation. The sinusoidal pattern is generated from 500kHz and above. The value of distributed capacitance determines the required region of high-frequency bandwidth at the secondary output. The portability, economy and simplicity make this superior to other conventional devices.

DOI:10.1049/ip-g-1.1980.0021

出版商:IEE    

年代:1980

数据来源: IET

摘要:

The synthesis of arbitrary waveforms by digital means offers great flexibility in parameter variation under program control. A major constraint, however, lies with accuracy of waveform definition unless many stored samples are employed. The paper examines an alternative hybrid-circuit approach that uses linear interpolation, at no sacrifice in control flexibility. The example of the sine approximation is treated in depth with a detailed theoretical appraisal followed by results on a prototype circuit.

DOI:10.1049/ip-g-1.1980.0022

出版商:IEE    

年代:1980

数据来源: IET

摘要:

The operation of a typical line-scan output/e.h.t. generator circuit is analysed in detail. The results are given as a set of equations which are solved by an APL program, details of which are included. The analysis demonstrates how the various voltages, currents and time intervals in the circuit vary with e.h.t. load current. An important characteristic of the circuit is e.h.t. voltage regulation; this is found to depend significantly on the transformer leakage inductance, and on the charge storage and forward resistance of the e.h.t. rectifier. Over a range of load current depending on the leakage inductance, regulation is substantially better than if the leakage inductance were zero. Another characteristic that shows a similar dependence on leakage inductance is the flyback time. Performance of a test circuit has been computed and compared with measurements. The computed output voltage is found to be about 5.5 to 7% high and the incremental internal resistance about 33% low; probably the result of ignoring transfomer losses.

DOI:10.1049/ip-g-1.1980.0023

出版商:IEE    

年代:1980

数据来源: IET

摘要:

TheYoperator,y= (1−z−1)/T, gives digital differentiation. Recursive digital filters are more conveniently designed using theyrather than thezoperator. It relates closely to Laplace transforms and to microprocessor algorithms. 1/yfilter elements give improved filter sensitivity to coefficient wordlength. Furthermore, accurate compensation can be made for sampling.

DOI:10.1049/ip-g-1.1980.0024

出版商:IEE    

年代:1980

数据来源: IET

摘要:

A scattering matrix approach to the design of microwave power combiners is presented. Both fixed and variablen-way combiners are discussed for power sources of different levels. Recursive expressions of output power in terms of input powers and coupling coefficients of couplers are derived which can be programmed on digital computers to predict the degradation in the event of source failure. For variablen-way combiners that are capable of producing truly graceful degradation, phase shift recursive expressions in terms of input powers are also derived which can be implemented on microprocessors to monitor and control the phase shifters.

DOI:10.1049/ip-g-1.1980.0025

出版商:IEE    

年代:1980

数据来源: IET

摘要:

A theory is presented concerning the timing-jitter accumulation in a chain of regenerative repeaters for optical-fibre transmissions. The timing circuit in each repeater is modelled as a phase-locked loop. The spectra of the timing jitter and of the alignment error at any repeater of the chain are expressed in terms of the various system parameters. The theory fits very well the results obtained by computer simulation.

DOI:10.1049/ip-g-1.1980.0026

出版商:IEE    

年代:1980

数据来源: IET