Abstract
Two simple voltage-controlled-oscillators (VCO) with linear tuning laws employing only a single current feedback operational amplifier (CFOA) in conjunction with two analog multipliers (AM) have been highlighted. The workability of the presented VCOs has been demonstrated by experimental results based upon AD844 type CFOAs and AD534 type AMs.
Highlights
A number of new building blocks and circuit concepts related to current-mode circuits have been investigated in recent literature [1,2,3], the use of current feedback operational amplifiers (CFOAs) as an alternative to the traditional voltage-mode op-amps (VOA), has attracted considerable attention in various instrumentation, signal processing and signal generation applications due to their commercial availability as off-the-shelf ICs as well as due to the well known advantages offered by CFOAs over the VOAs
We highlighted two simple CFOAAM-based Voltage-Controlled Oscillators (VCO), providing linear tuning laws, which are derivable from previously known op-amp-analog multipliers (AM) based VCOs published in [14]
The workability of the new VCOs has been confirmed by the experimental results, based upon AD844 type CFOAs and AD534 type analog multipliers
Summary
A number of new building blocks and circuit concepts related to current-mode circuits have been investigated in recent literature [1,2,3], the use of current feedback operational amplifiers (CFOAs) as an alternative to the traditional voltage-mode op-amps (VOA), has attracted considerable attention (see [4,5,6,7] and the references cited therein) in various instrumentation, signal processing and signal generation applications due to their commercial availability as off-the-shelf ICs as well as due to the well known advantages offered by CFOAs over the VOAs. A known method of realizing VCOs is to devise an RC-active oscillator configuration with two analog multipliers (AM) appropriately embedded to enable independent control of the oscillation frequency through an external control voltage VC applied as a common multiplicative input to both the multipliers. When two AMs are appropriately embedded in such a configuration, this technique gives rise to a linear tuning law of the form f0 VC (1). Based upon this approach, a number of VCO configurations have been proposed by various researchers in the past [12,14,15,16,17] employing traditional VOAs and AMs. D. CFOA-based VCOs as compared to previously known VOA-based VCOs of [12,14,15,16,17] have been highlighted
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