Current-Mode Electronically-Tunable Sinusoidal Oscillator Based on a Shadow Bandpass Filter

The design of a current-mode frequency and amplitude-controlled sinusoidal oscillator, is presented. The oscillator is based on a second order G
m
-C bandpass filter made up of low-voltage current mirror cells. The frequency response of the filter can be modified by means of its biasing current. Besides, an automatic control circuit that ensures oscillation and leads to the desired amplitude of the output signal, has been included. The proposal has been designed and implemented in 180 nm CMOS technology to operate with a supply voltage of 1.8 V, resulting in a compact solution very appropriate for operation in low-voltage environments. The simulated results show high speed, with a maximum bandwidth of 2.75 MHz, and linear response, with a THD of around −40 dB for an output amplitude of 5 μA.