Parasitic discrete-time-pole cancelling techniques for ultra-wideband discrete-time charge-domain baseband filters

Parasitic discrete-time-pole cancelling techniques that use a discrete-time IIR BPF are presented. Parasitic capacitors, which usually cause undesirable lowpass parasitic discrete-time poles in ultra-wideband applications, are utilized to provide bandpass parasitic discrete-time poles, thus improving the frequency characteristics in parallel with passband equalizer circuits. A novel charge transfer scheme that reduces the parasitic sensitivity of the output nodes is also implemented. The prototype filter has been implemented with a 90 nm CMOS technology. Measurements show that a 250-MHz cutoff, 0-db gain discrete-time charge-domain filter and an 8-phase clock pulse generator dissipate 8 mA and 1 mA, respectively, from a 1.2-V supply voltage.