Electronically Tunable Differential Integrator: Linear Voltage Controlled Quadrature Oscillator

Abstract

A new electronically tunable differential integrator (ETDI) and its extension to voltage controlled quadrature oscillator (VCQO) design with linear tuning law are proposed; the active building block is a composite current feedback amplifier with recent multiplication mode current conveyor (MMCC) element. Recently utilization of two different kinds of active devices to form a composite building block is being considered since it yields a superior functional element suitable for improved quality circuit design. The integrator time constant (τ) and the oscillation frequency (ω o) are tunable by the control voltage (V) of the MMCC block. Analysis indicates negligible phase error (θ e) for the integrator and low active ω o-sensitivity relative to the device parasitic capacitances. Satisfactory experimental verifications on electronic tunability of some wave shaping applications by the integrator and a double-integrator feedback loop (DIFL) based sinusoid oscillator with linear f o variation range of 60 KHz~1.8 MHz at low THD of 2.1% are verified by both simulation and hardware tests.

Electronically tunable allpass filter: linear VCO design

“…2; error e was seen to be small for the ETAF while the THD-level (upto 7 th harmonic) for both ETAF and QVCO is quite low compared to [10,29,30,32]. Tuning error in Table II is measured upto 3.3 MHz by a new method here by evaluating the phase margin of the loop at gain-crossover frequency.…”

“…A relevant comparative summary to this extent is presented in Table I. It may be seen that albeit electronically tuned QVCOs are also proposed earlier [10,26,27,28,29,30,31,32], but such an oscillator based on electronically tunable AP filters with linear tuning law had not yet been presented, as is seen by the comparative description in Table I below.…”