A tunable switched-capacitor programmable N-path tone receiver and generator

A continuously variable tuning technique for switched capacitor filters

“…This result was confirmed by comparing the measured THD with the theoretical value for the amplitude of the second-harmonic distortion as a fraction of the fundamental for a single FET operating in the linear region (HD2). Elementary analysis shows this fraction to be given by the (4) and (5) and using the value of R discussed above, second harmonic distortion is -48.8 dB below the fundamental which is in agreement with the measured value. In addition, the VSC was simulated using HSPICE In this case the second harmonic distortion was -48.4 dB, again, in close agreement with the measured value.…”

“…The SC technique has an additional advantage in that it can use multi-path techniques to achieve very high Q [4]. For example, a tone receiver and generator for a mobile-radio system, using a pseudo-N-path filter to obtain a maximum tunable Q of 200 has been demonstrated [5].…”

“…A wide variety of techniques have been developed in the last three decades for obtaining reduced-order models. Representative methods include the Pad6 class of approximations [l], the Routh approximation [2], [3], the optimal Hankel-norm approximation [4], [5], the balancing reduction [6], [7], and the optimal approximation based on minimizing certain performance indexes involving time or frequency response errors [8]- [12]. These model reduchon techniques were originally proposed for stable systems.…”