A low noise and highly linear wideband RF front-end circuit for sub-㎓ Internet of Things (IoT) applications is proposed. The proposed frontend is composed of a broadband single-ended LNA, a wideband differential LNA employing thermal noise cancellation technique, and an in-phase and quadrature (I/Q) linearized harmonic rejection mixer (HRM). Depending on the interference environment, the proposed front-end supports two operation modes having high sensitivity and selectivity performance by enabling or disabling the first building block of the single-ended LNA. At high sensitivity mode, the frontend shows a voltage gain (A<SUB>v</SUB>) of greater than 38 ㏈, a noise figure (NF) of less than 2.1 ㏈, an input-referred third-order intercept point (IIP3) of greater than -23 ㏈m, and an input-referred second-order intercept point (IIP2) of greater than +15 ㏈m in the sub-㎓ frequency band. Concerning for high selectivity mode, it achieves an Av of greater than 22.5 ㏈, a NF of less than 4.7 ㏈, an IIP3 of greater than – 6.8 ㏈m, and an IIP2 of greater than +50 ㏈m over the same operating frequency range.
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