fT-integration based continuous-time filters for very high frequencies

Fully functional integrator and bandpass filter based on the f_T-integration technique are experimentally demonstrated for the first time using general purpose npn/pnp transistor arrays. The circuit configurations employed offer enhanced performance compared to the originally introduced f_T-integrator structure with lower supply voltage, more accurate frequency control and less chip area while still maintaining a wide frequency tuning capability. The integrator prototype achieves -52 dB total harmonic distortion (THD) and -42 dB third-order intermodulation distortion with a unity-gain frequency tuneable from 20 MHz to 55 MHz. The bandpass filter also obtains a centre frequency tuning over one octave (from 23 MHz to 51 MHz) with -50 dB THD, 34 dB spurious free dynamic range and 1 dB-compression dynamic range of 40 dB at Q=12. Both circuits are able to operate successfully at frequencies beyond one-sixth of npn´s f_T and more than six-times of pnp´s f_T