Systematic Synthesis and Design of Ultralow Threshold 2:1 Parametric Frequency Dividers

Abstract

A new method is discussed for the systematic synthesis, design and performance optimization of varactor-based parametric frequency dividers (PFDs) exhibiting an ultra-low power threshold (P th ). For the first time, it is analytically shown that the P th -value exhibited by any PFD can always be expressed as an explicit closed-form function of the different impedances forming its network. Such a unique and unexplored property permits to rely on linear models, during the PFD design and performance optimization. The validity of our analytical model has been verified, in a commercial circuit simulator, through time-domain and frequency-domain algorithms. To demonstrate the effectiveness of our new synthesis approach, we also report on a lumped prototype of a 200:100MHz PFD, realized on a printed circuit board (PCB). Although inductors with quality factors lower than 50 were used, the PFD prototype exhibits a P th -value lower than −15dBm. Such a low P th -value is the lowest one ever reported for passive varactor-based PFDs, operating in the same frequency range.

A chip-less and battery-less subharmonic tag for wireless sensing with parametrically enhanced sensitivity and dynamic range

“…1 d), where is the output power at delivered to the antenna used for transmission. , which designates the minimum input power at which a SubHT can operate, is set by the junction capacitance and tuning range exhibited by the adopted varactor, along with the impedances that such variable capacitor sees at both and 27 . These impedances are set by the equivalent passive network formed by the selected lumped components excluding the varactor.…”

“…The thermistor was used as the required sensitive element in the SubHT stabilization network, allowing its unique temperature-sensitive dynamics. Following our recent theoretical investigation on the stability of varactor-based parametric systems 27 , and given the impedance exhibited at room temperature by the selected thermistor, the inductors and capacitors of the built SubHT were selected to minimize at equal to 886 MHz. This was done by satisfying four resonant conditions allowing the maximum voltage level across the varactor at , the minimum leakage of towards the receiving antenna and the lowest impedance magnitude seen by the varactor at .…”

“…These unique features enable orders of magnitude higher SNRs at the receiver of the interrogating nodes than what has ever been possible to achieve through harmonic tags, hence paving the way towards a more accurate wireless sensing and a longer communication range. Furthermore, we show that the unexplored parametric dynamics leveraged by SubHTs [24][25][26][27] also allow to massively boost the sensitivity and the dynamic range attained by off-the-shelf commercial sensors, thus providing the means to achieve superior sensing capabilities without requiring advanced on-chip sensors like the recently developed MEM/NEM components.…”

Chip-Less and Battery-Less Subharmonic Tags for Wireless Sensing with Parametrically Enhanced Sensitivities and Dynamic Ranges

“…The thermistor was used as the required sensitive element in the SubHT stabilization network, allowing its unique temperature-sensitive dynamics. Following our recent theoretical investigation on the stability of varactor-based parametric systems 27 , and given the impedance exhibited at room temperature by the selected thermistor, the inductors and capacitors of the built SubHT were selected to minimize P th at f in equal to 886MHz. This was done by satisfying four resonant conditions allowing the maximum voltage level across the varactor at f in , the minimum leakage of P out towards the receiving antenna and the lowest impedance magnitude seen by the varactor at f out .…”

“…Furthermore, while our preliminary measurements 53 already showed that the built SubHT enables longer communication 54 ranges, up to 7 meters, even longer ranges are expected in the future 55 through further technological and design developments. For instance, 56 as we theoretically discussed in27 , the minimum parametric power 57 threshold exhibited by any varactor-based parametric system is ul-58 timately set by the load and source characteristic impedances that, 59 for SubHTs, represent the input impedances of the adopted antennas. 60 Hence, through the future use of custom low-impedance (<10Ω) an-61 tenna designs, we anticipate to reduce this power threshold by more 62 than 200 times, thereby enabling much longer communication ranges 63 and higher sensitivities, which will be exclusively limited by the re-64 ceiver's power sensitivity and by the noise floor of the interrogating…”