Monolithic v.c.c.s. for high-frequency RC active filters

A monolithic voltage-controlled current source designed for the realisation of high-quality RC active filters at frequencies up to 1 MHz is described. The chip is fabricated using standard 741 technology with lateral p-n-p transistors, and requires no internal compensation for stabilisation.     

More active RC filters using the d.v.c.c.s./d.v.c.v.s.

Novel configurations using a differential-voltage-controlled current source, differential-voltage-controlled voltage source (d.v.c.c.s./d.v.c.v.s.) as the active building block are described. The configurations assume that the active building block is divided into two independent parts initially.     

Active RC bandpass and lowpass filters using the d.v.c.c.s./d.v.c.v.s.

A novel configuration using the differential voltage-controlled current source, differential voltage-controlled voltage source (d.v.c.c.s./d.v.c.v.s.) as the active building block is introduced. The realisations of bandpass and lowpass filters are given as special cases; both filters are canonic, and a moderate pole Q-factor can be obtained in each case.     

Integrated n.m.o.s. operational amplifier for c.c.d. transversal filters

An integrated operational amplifier employing a new high-gain input stage and implemented with n.m.o.s. enhancement devices is reported. The circuit has been designed with reference to the output differential-charge amplifier of a c.c.d. transversal filter. The performance parameters of the amplifier are presented.     

New charge-differencing technique for c.c.d. transversal filters

A new charge-differencing technique for use with c.c.d. transversal filters employing charge sensing is described. The method eliminates the need for a voltage-differencing amplifier and requires the addition of one extra matched capacitor.     

Coefficient correction in programmable c.c.d. recursive filters

A technique for correcting coefficient errors in c.c.d. recursive filters is described. The technique is demonstrated on a programmable second-order Chebyshev lowpass filter.     

Scratch filter using c.c.d.s

This letter describes the use of charge-coupled devices in the automatic real-time editing of audio signals. A simple semiconductor device is used to replace a number of complex digital circuits.     

Parallel-in/serial-out: a new approach for c.c.d. transversal filters

A new principle for a c.c.d. transversal filter with parallel inputs is shown. Using this approach, no differential output amplifier is necessary. Design considerations of a device successfully tested are reported and the first measured results are compared with theoretical predictions.     

Cascaded s.a.w. gratings as passband filters

A design procedure is given for cascades of grating resonators to construct Tchebysheff, Butterworth, Gaussian, Legendre and other passband filters.     

Fast-Fourier-transform processor using s.a.w. chirp filters

A fast-Fourier-transform (f.f.t.) processor based on the chirp transform algorithm implemented with surface-acoustic-wave (s.a.w.) chirp filters is reported. Using commercially available s.a.w. devices the processor computes a 128-point (nominal) f.f.t. in 25 ?s, permitting real-time operation over 4 MHz bandwidth. Experimental results showing operation with sine and cosine inputs demonstrate processor performance in computing real and imaginary Fourier-transform components to an accuracy equivalent to 6 bits.     

视频放大器/滤波器的模拟要求和实施

模拟滤波 为什么模拟视频要使用过滤技术呢?如前所述,将模拟视频信号与数字视频信号相互转换是很常见的.对显示器和DVD刻录机等接收设备来说,这就需要使用模数转换器(ADC).对机顶盒和DVD播放器来说,就需要使用数模转换器(DAC).ADC和DAC提供的画质都取决于采样频率.     

Reduction of high-level nonlinear smearing in c.c.d.s.

It is shown that the distortion caused by nonlinear smearing at high signal levels in charge-coupled devices may be vastly reduced by only using alternate signal inputs, followed by summation of the signals in adjacent cells at the output.     

Two-dimensional inverse filter using floating-gate tapped c.c.d.s

A two-dimensional inverse filter has been implemented using floating-gate tapped c.c.d.s. The least-mean-square criterion was applied to obtain tap gains. Filter responses in both frequency and time domains were examined. Results confirm that the two-dimensional inverse filter can effectively eliminate both intersymbol and crosschannel interferences.     

Floating ideal inductor with one d.v.c.c.s.

A floating-ideal-inductor realisation scheme with one d.v.c.c.s., two amplifiers and a grounded capacitor is presented. It is also shown that, from this scheme, a grounded-capacitor/three-amplifier floating-ideal-inductor realisation scheme can be easily derived.     

Frequency-hopped waveform synthesis by using s.a.w. chirp filters

The design and construction of a surface-acoustic-wave (s.a.w.) pseudonoise (p.n.) code controlled frequency-hopping (f.h.) synthesiser for spread-spectrum (s.s.) communication is reported. The prototype synthesiser uses s.a.w. chirp filters with 60 MHz centre frequency, 5 MHz/?s is dispersive slope and 25 MHz bandwidth, and operates in both continuous-wave and f.h. modes. Experimental results show an output centred on 120 MHz, electronically programmable over a 25 MHz bandwidth in 63 discrete hops.     

AlGaAs heterostructure injection laser s.c.r.

The operation of a gate-controlled p-n-p-n injection laser device has been demonstrated. The switching is accomplished by an electrical control signal. The threshold current of the laser incorporated into the device is about 100 mA, and its optical properties are similar to those of the Be-implanted laser reported recently.     

Lossless inductor simulation: novel configurations using d.v.c.c.s.

Novel lossless grounded and floating inductor simulating networks using only one grounded capacitor and the differential voltage-controlled current source (d.v.c.c.s.) active elements are proposed.     

Radar Doppler processing using c.c.d and s.a.w. devices

Combining the attributes of charge-coupled-device analogue signal processors with those of surface-acoustic-wave devices promises a compact and inexpensive way of extracting Doppler frequency information from coherent pulse-radar signals. Experimental tests confirm the feasibility of the technique and point the way to a fairly simple processing module which should be applicable to a range of radar parameters.