{'fraction_non_alphanumeric': 0.03132938187976291, 'fraction_numerical': 0.015241320914479255, 'mean_word_length': 5.221052631578948, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 2, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Tunable selective receiver front end with impedance transformation filtering

A highly selective impedance transformation filtering technique suitable for tunable selective RF receivers is presented in this paper. To achieve blocker rejection comparable with surface acoustic wave (SAW) filters, we use a two‐stage architecture based on a low‐noise transconductance amplifier (LNTA). The filter rejection is captured by a linear periodically varying model that includes band limitation by the LNTA output impedance and the related parasitic capacitances of the impedance transformation circuit. This model is also used to estimate ‘back folding’ by interferers placed at harmonic frequencies. Discussed is also the effect of thermal noise folding and phase noise on the circuit noise figure. As a proof of concept, a chip design of a tunable RF front end using 65 nm complementary metal‐oxide‐semiconductor (CMOS) technology is presented. In measurements, the circuit achieves blocker rejection competitive to SAW filters with noise figure 3.2–5.2 dB, out of band IIP3 > +17 dBm, and blocker P1dB > +5 dBm over frequency range of 0.5–3 GHz. Copyright © 2015 John Wiley & Sons, Ltd.