A new wide input range square-rooting circuit is presented. The proposed circuit consists of a dual translinear loop, an absolute value circuit, and current mirrors. A current-mode technique is used to provide wide input range with simple circuitry. The output signal of the proposed circuit is the current which is proportional to the square root of input current. The proposed square-rooting circuit was confirmed by using PSpice simulator program. The simulation results demonstrate that the proposed circuit provides the excellent temperature stability with wide input current range.

A square-rooting circuit is
widely used in analog instrumentation and measurement systems. For example, it is used to linearize a
signal from a differential pressure flow meter, or to calculate the root mean square value of an arbitrary waveform [

This paper, a new BJT wide input range current-mode square-rooting circuit, is introduced. It consists of a dual translinear loop, an absolute value circuit, and current mirrors. The proposed square-rooting circuit is operated in current mode that has the following advantages.

The square-rooting circuits of Filanovsky and Baltes [

The proposed square rooting is suitable for bipolar IC technology.

The proposed square rooting provides wide input current range.

The proposed square rooting provides excellent temperature stability.

It possesses high output impedance.

Figure

Dual translinear loop.

Figure

Absolute value circuit.

Figure

Proposed dual-output current-mode square-rooting circuit.

In the practical realization, the device mismatch between NPN and PNP bipolar
transistors groups of

The square-rooting circuit in
Figure

Figure

Simulated DC transfer characteristics of proposed square-rooting circuit: (a) positive input; (b) negative output.

Figure

Operation of circuit for the 100 kHz input triangular signal: (a) input waveform; (b) output waveforms.

Operation of circuit for the 100 kHz sine wave input signal: (a) input waveform; (b) output waveforms.

Simulated result for frequency responses.

To demonstrate the performance of the proposed square-rooting circuit, Figure ^{°}C, 75^{°}C, and
100^{°}C
temperatures while applying the 100 kHz frequency triangle wave with 2 m

Operation of circuit for the 1 MHz input triangular signal: (a) input waveform; (b) output waveform.

Output waveforms at different temperatures at 100 kHz frequency input signal.

In this paper, a new current-mode square-rooting circuit is presented. The proposed circuit employs a dual translinear loop, an absolute-value circuit, and current mirrors. Simulation results show that the proposed square-rooting circuit provides the wide input current range with excellent temperature stability. Better performance can be expected by using the bipolar transistors and the parameters of complementary high performance processes which were not available to the authors. The proposed square-rooting circuit is suitable for IC fabrication because of the absence of the external resistor.