Electronically Tunable Dual-Input Integrator Employing a Single CDBA and a Multiplier: Voltage Controlled Quadrature Oscillator Design

Figure 2

Experimental results.

(a) Integrator response with square wave excitation of 𝑉₁=−𝑉₂=2.5 V(peak) at 1 MHz using 𝑅₁=𝑅₂=𝑅=10 K.ohm, 𝑅₄=60 K.ohm, 𝑅₃=30 K.ohm, 𝐶=100 pF, 𝐶_𝑧 (measured) =7.2 pF, and 𝑉_𝑐=5 V.d.c.

(b) VCQO-tuning characteristics with 𝐶=1 nF

(c) VCQO wave-response with build-up feature tuned for 𝑓_𝑜=1.02 MHz

(d) Nyquist plot of loop function 𝐹₁𝐹₂(𝑠) measured in the vicinity of 𝑢=1±10% with above keys. Nominal tuned frequency (𝑓₀): A → 1 MHz B → 0.72 MHz C → 0.5 MHz

(e) Frequency spectrum of the loop-function 𝐹₁𝐹₂(𝑠) measured at the tuned frequency of 1 MHz