CMOS voltage and current feedback opamps: a comparison between two similar topologies

Abstract

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Design and Implementation of Self-Limiting Two-Stage LC Oscillators Using Cascade Structure of Monolithic CCIIs as Active Elements

“…The instability is also defined as a phase noise in the oscillator circuits. Analytically, the phase noise is related to the frequency stability coefficient, given by Formula (17). Moreover, this value is directly proportional to the equivalent quality factor of the circuit.…”

“…The monolithic positive second-generation current conveyors (CCII+s) pr Sedra and Smith can be considered as current sources, controlled by the value rent at the inverting input terminal of the integrated circuit [16,17]. The symbol tation and the ideal equivalent circuit diagram of the CCII+ are given in Figur spectively.…”

“…One possible solution is to use monolithic current conveyors [16,17] as active elements in electronic oscillator circuits [8,9,11,13], which can largely combine some advantages of the possible realization of the CCII+s using commercially available Current-Fee erational Amplifiers (CFOAs) with an external terminal z is given. The princip structure of the proposed two-stage LC oscillator circuits are given in Section 3 their basic electrical parameters.…”

Development of Two-Stage Quartz-Crystal Oscillators Using Monolithic Four-Terminal CFOAs

“…One possible method to simplify the circuit structure and improve the electrical parameters of crystal oscillators with op-amps as active elements is by using monolithic positive second-generation current conveyors (CCII+s) [1,19] or monolithic four-terminal current-feedback operational amplifiers (CFOAs) [20][21][22]. These types of op-amps are characterized by one non-inverting high-impedance input terminal-y, one inverting lowimpedance input terminal-x, and one high-impedance output terminal-z in the CCII+.…”

“…Based on the two-stage self-limiting series mode type quartz-crystal oscillators presented in [10] and some applied circuit configurations given in [21][22][23]27], in this work, the author has tried to develop electronic circuits of two-stage quartz-crystal oscillators containing a minimum number of external passive components and providing the possibility for high stability (high value of the equivalent quality factor). Furthermore, some of the circuit variants used crystal units operated at the series resonant frequency, and the other circuits used crystal units operated at a frequency slightly above series resonance, where the equivalent impedance is with a positive sign (or has inductive character).…”