CMOS RLC and crystal oscillators based on current conveyors

New Quartz Crystal Oscillators Using the Current‐Feedback Operational Amplifier

“…Each circuit uses one CFOA, a crystal and, at most, five externally connected passive elements. Experimental results are included.Keywords: Oscillators; Current-feedback operational amplifier current-conveyor (CCII) [3][4][5]. Because the CCII minimally degrades the quartz crystal performance, CCII-based crystal oscillators enjoy good frequency stability and are, therefore, very attractive [3].On the other hand, the current-feedback operational-amplifier (CFOA) is a four-terminal device which is equivalent to a CCII plus an output voltage buffer and, thus, it can easily drive external loads.…”

“…Keywords: Oscillators; Current-feedback operational amplifier current-conveyor (CCII) [3][4][5]. Because the CCII minimally degrades the quartz crystal performance, CCII-based crystal oscillators enjoy good frequency stability and are, therefore, very attractive [3].…”

“…reduces to a second-order polynomial in s. Equating the real and imaginary parts, of this second-order polynomial to zero, yields CoR)((C2/C1) + 2(C4/C1)+ 2(r/R) + 1)+ (1/RC1)(5) (L1/R)((C2/Co) + 2(C4/C0) + 1) + C2r((C4/Co) + 1) and 2/(R2CICo) (C2/Co)((C4/C1) + (r/R) + 1) +2(C4/Co)(r/R) +2(LI /RZCo) + (C2/C(6) With C1 << Co, r << R, Eqs. (5) and (6) can be approximated by L1C1 and (8) it obvious than wp and wn are approximately equal and thus, the circuit can oscillate at a frequency approximately given by the series-resonance frequency of the crystal.…”

CMOS implementation of low-power oscillators based on the modified Fabre-Normand current conveyor

“…RC and crystal oscillators are realized by connecting capacitor C or a quartz crystal, respectively, at node X. Analysis of this circuit reveals that the real part of the roots of the system's characteristic equation is always positive and large, approximately equal to lRrnl/Lp~ [3], ensuring reliable and quick build-up of oscillations. To provide low-voltage, low-power operation, we replaced improved Wilson with simple current mirrors without affecting the circuit functionality [7]: The RC oscillator with modified Fabre-Normand circuit is shown in Figure 3.…”

“…The input capacitance of such transistors is large and it significantly reduces the frequency range of the circuit. This problem is overcome by realizing the oscillators as integrated circuits [3]. I n comparison to other IC realizations of oscillators with current conveyors, the oscillators presented here have significantly smaller current consumption and approximately the same operating frequency range.…”