A switched capacitor oscillator with precision amplitude control and guaranteed start-up

A description is given of the design and performance characteristics of a precision switched capacitor (SC) oscillator. Features of this circuit include precision control over both frequency and amplitude, as well as means to ensure that oscillations start regardless of power-up sequence, reasonable offsets, etc. Many attributes of this oscillator are obtained by exploiting the unique properties of switched capacitor circuits; the proposed circuit does not possess a direct active-RC counterpart. The authors include derivations of analytical expressions for output frequency, amplitude, and harmonic distortion.