Study of impact of voltage gain of comparator on performance of newly designed functional generator

Abstract

This paper focuses on analysis of impact of voltage gain of comparator on features of designed triangular and sine wave generator. Newly designed generator employs minimal number of passive and active components based on simple voltage controllable amplifier and electronically controllable current conveyor or adjustable current amplifier. The generator has simple structure with easily available electronic control of repeating frequency and duty cycle. Detailed PSpice analyses of the modified generator are provided and relevant results of experimental measurements are shown. Discussion of non-ideal effects of voltage gain (A) of controllable amplifier used as comparator on generated amplitudes, on repeating frequency and on duty cycle as well as effects of statistical dispersion of important parameters are given. Observed behavior was analyzed not only by simulations but also by experimental measurements.

Design of Signal Generators Using Active Elements Developed in I3T25 CMOS Technology Single IC Package for Illuminance to Frequency Conversion

“…The OTA and R2 create a very simple Schmitt trigger [1]. Note that many researchers refer to the interconnection of the CCCII and OTA as current conveyor Many concepts use standard commercially available AEs (e.g., operational transconductance amplifiers (OTAs) [5,6], current conveyors [10], operational amplifiers [14,25], variable gain amplifiers [14,16,17], or their easily accessible models, i.e., internal topologies). In numerous works, the active subparts of basic building structures [2,3] are understood as a single element [7][8][9][11][12][13]15,[18][19][20][21][22][23].…”

“…In fact, many of these devices include several functional active subparts. In some cases, the experimental verification was obtained from the behavioral model of a hypothetical AE [9,13,[16][17][18][19]22,23,26]. Generally, this method is useful and frequently used by researchers.…”

“…Our solutions bring more compact real circuitry of triangular and square wave generators preserving features of already known concepts, but significantly reduce the number of required active components (comparable to the rest of solutions, see Table 1) and area of the circuitry. Concepts presented in [5,6,14,16,17,24,25] use standard active elements that are commercially available (easily accessible for designers-significant advantage). However, there are some disadvantages, namely: High power consumption (information is not available in many papers), high area requirements, high number of passive elements for serial production of a final application.…”

“…From a practical point of view (number of real IC packages in measurements), our solution seems to be the simplest. Moreover, there is a limited number of electronically tunable generators employing integrator with the current conveyor [10,14,15,17,[24][25][26] in standard [10] or controllable form (gain [2], [3] adjusted in [14,15,17,25]. These circuits utilize linear operation of the current conveyor.…”

“…Due to the large level of OTA's output current flowing through the resistor R 2 , the maximal voltage V sq reaches the saturation level slightly below the approximated ±1.5 V at the supply voltage of ±1.65 V. Therefore, when V Y > ±0.5 V (for CCCII; in fact, when V sq > ±0.5 V as obvious) then the maximal value of the current charging the C is given as: I Cmax = 10•I B (exactly valid for I B ≤ 120 µA). It is not typical in the case of similar solutions (integrator using current conveyor) because I Cmax is frequently given by the saturation voltage (V sq ) and it is, therefore, allowed only in linear dynamics of the current conveyor (see [14,15,17]). The constant value of 10 results from mirroring gains of the internal topology of the CCCII cell [4].…”