Design and Applications of Minimally Invasive All-Pole Analog Filters

Abstract

A new design technique for minimally invasive all-pole analog lowpass filters is introduced and the concept of minimally invasive filtering has been generalized for higher orders both in voltage-mode and current-mode operations. The proposed fully differential solution has minimal impact on the in-band signal in terms of added noise and nonlinearity, whereas it has comparable performance for out-of-band signals using smaller number of active devices.

Extending the concept of current-mode minimally invasive filters, a novel baseband circuit with third order filtering has been designed, which has comparable linearity and noise with approximately half the power consumption when compared to the conventional solution. The proposed baseband circuit has a bandwidth of 10MHz, achieves 44dB rejection at 50MHz (40dB in post-layout simulations), low broad-band input impedance of 10.16ohm with a comparable noise and linearity at a lower power consumption when compared to a third order conventional circuit. The circuit has been designed in TSMC 130nm technology and is integrated with a broad-band receiver front-end including an LNA and a mixer.