Impedance Converter Circuit Research Articles

Novel CMOS differential voltage current conveyor and its applications

Novel CMOS realisations of a differential voltage current conveyor (DVCC) are described. These circuits are powerful building blocks, especially for applications demanding differential or floating inputs like impedance converter circuits and current mode instrumentation amplifiers. Applications suitable for VLSI are then considered by using the DVCC to realise a MOS transconductor and a continuous-time current mode MOSFET-C filter. PSpice simulations indicate the excellent performance of the proposed DVCC and of its circuit applications.

Negative impedance converter with a translinear implementation

A new negative impedance converter circuit, which is a current inversion type (I-NIC), is described. The basic cell consists of a mixed translinear loop comprising two pnp and two npn bipolar transistors. This cell is used in conjunction with a constant current source and two complementary current mirrors. The characteristics and the properties of the practical realization are presented and discussed. A new bandpass filter, which is a current processing circuit, using the I-NIC and a current-controlled current source (CCCS) are also introduced. Experimental results are given.

Some negative impedance converters

Four new transistor-resistor negative impedance converter circuits are presented, two of the voltage-inversion type and two of the current-inversion type. Their gain-product sensitivities are tabulated.

A method for determining the pH of small quantities of fluid

The micro-glass electrode used in measuring the pH of blood from the stomachs of mosquitoes was a modification of that described by Caldwell (1954). The electrode was made of capillary tubing, drawn from Corning 015 glass, the outer diameter being 0·5–0·75 mm. and the length about 6 cm. As the electrode was used with a Pye Universal pH meter, and not with the electrometer impedance converter circuit used by Caldwell, it was important that the wall of the capillary tube should be very thin, in order that the resistance of the electrode should not exceed 500 MΩ, the maximum electrode resistance permissible with the Pye Universal pH meter.