Charge-coupled-device analogue matched filters

Charge-coupled-device shift registers are used to construct filters matched to both a 13-chip Barker-coded p-n sequence and a chirp signal with a time-bandwidth product of 10. The letter describes the design and fabrication of the devices, and presents preliminary operational characteristics of the filters. A 5 MHz chip rate for the Barker code filter is demonstrated     

Logarithmic convertor

A specialised system for computing logarithms and anti-logarithms in binary form is described. A great simplicity is obtained if the base is of the form 1+2?k. The precision is discussed and two examples are given. The computing time is, with t.t.l. circuits, of the order of 1 ms in the usual range of the analogue logarithmic convertors, and does not increase very much when the range of the numbers and the precision increase.     

Direct-coupled negative-impedance convertor

Negative-impedance convertors for lowpass active RC filters must respond down to zero frequency; any attendant drift is unwelcome. A relatively simple circuit is described wherein a balanced input stage feeds an unbalanced output stage, which, in turn, feeds back to both input terminals in the same phase.     

Charge-transfer analogue-to-digital convertor

A novel means of implementing an analogue-to-digital conversion function by charge-transfer techniques is described. The number of metered charge packets that is required to fill a potential `well? to a predetermined threshold level is linearly proportional to the magnitude of the input analogue voltage. Circuits have been implemented using p-channel, aluminium-gate technology, and have demonstrated 10?12 bits resolution capability.     

Self-oscillating regulated convertor

A self-oscillating transformer-coupled d.c.-d.c. convertor is presented in which the voltage-regulation feedback loop serves the additional function of establishing the self-oscillations required for d.c.-a.c. inversion. This self oscillating regulated convertor offers greater circuit economy than conventional regulated convertors, in which inversion and regulation are separate functions.     

Simple negative-impedance convertor

The use of controlled (dependent) current sources in designing negative-impedance converters (n.i.c.) is well known. A simple d.c.-coupled n.i.c. circuit which has temperature-compensating features is described.     

Rapid pulse-frequency-number convertor

A circuit is described which will convert the repetition rate of a pulse train into a number, continuously but with very little lag. The circuit is considerably simpler than one recently described, and performs satisfactorily provided that the pulse rate does not vary too rapidly.     

Acoustic-surface-wave analogue-digital convertor

An analogue-digital convertor that employs an acoustic-surface-wave transducer code plate is described. An experimental a.d. encoder with 4 bits of resolution and a 3 MHz sampling rate has been implemented with an LiNbO3 surface-wave structure.     

Accurate broadband square-to-triangle convertor

The convertor has been used to generate a sinusoid, in conjunction with a piece-wise linear network. A bandwidth of 105 Hz has been obtained; distortion is typically 0.2% over the frequency range 2 Hz?25 kHz.     

Wideband translinear current convertor

A bipolar current-to-current convertor (CCCS) using a PNP-NPN translinear loop and two current mirrors is described. This convertor has a virtual earth input, and may be used to realise voltage-current conversion (VCCS). This convertor configuration enables us to obtain a wideband frequency response. The characteristics of a practical current source are presented.     

GaAs-GaAlAs anti-Stokes light convertor

A multilayer heterojunction device has been manufactured and used for efficient anti-Stokes light conversion. The device consists of six layers: p GaAs, n GaAs, n GaxAl1?xAs, p GayAl1?yAs, p GaxAl1?xAs and p GaAs, essentially forming a GaAs photodiode coupled with a GaAlAs l.e.d. Avalanche multiplication of photoexcited carriers is used to increase the l.e.d. driving current.     

New wideband sigma-delta convertor

A new kind of sigma-delta modulator made with a double integrator and a bandpass stage is presented. It can reduce the oversampling ratio or increase the bandwidth for a constant sampling frequency compared with equivalent complexity modulators.<>     

Inductance-less up DC-DC convertor

A new type of up convertor which does not include inductance is described. Voltage multiplication is achieved by charging the capacitors in parallel and discharging them in series. The circuit includes two groups of switched capacitors which are alternately connected to the source and the load, such that the input charging pulses and output ripple are reduced, compared with a circuit including only one group of switched capacitors. This type of convertor may be applied in high-voltage systems, and because there is no inductance, it can also be included in integrated circuits.     

Active clamp dual-end convertor

An active clamp dual-end convertor is proposed to achieve zero voltage switching for all switches with low voltage stress and eliminate the DC current component in the transformer. A 40 W prototype is built and the experimental results are obtained for verification     

Wide-range temperature/frequency convertor

A novel wide range temperature/frequency convertor, based on comparing the current through a thermistor and the capacitor discharging current, is described. The input/output relationship is linear over a wide temperature range. The performance fitting has to be done only at the maximum temperature of the range. The convertor can be made multirange by simple modification of the circuit.     

New constant-frequency multiresonant boost convertor

A new zero-voltage-switching multiresonant boost convertor operating at constant switching frequency is presented. Its output voltage is regulated by controlling the freewheeling period of the resonant inductor. It possesses the advantages of a PWM convertor and frequency-modulated multiresonant convertor. Moreover, by absorbing all major parasitic components in its resonant circuit, parasitic ringing is eliminated.<>     

Class ab bipolar voltage-current convertor

A class AB voltage-current converter is described. The circuit is basically a modified version of Widlar's composite n-p-n transistor structure. 1, 2 The overall network combines extended drive-current capability with good small-signal properties over a useful frequency range.     

Improved switched-capacitor algorithmic analogue-to-digital convertor

A novel switched-capacitor circuit is presented for algorithmic analogue-to-digital conversion. Besides the reduced component count, the proposed circuit shows that it can accept a differential analogue signal. A conversion accuracy higher than 12 bits is easily attainable with its integrated version.     

High-accuracy digital?analogue convertor

High-precision constant-current sources of a novel design, based upon super beta integrated operational amplifiers, are used with the inverted ladder network to implement a classical digital?analogue-convertor configuration with an accuracy better than 0.01% over the full temperature range without external trimming.