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Recent advancements in the area of telemedicine have focused on remote patient monitoring services as a new frontier in medical applications. The present work reports a 65‐nm complementary metal–oxide–semiconductor (CMOS)‐based transimpedance amplifier (TIA) in an optical radar system for non‐contact patient monitoring. A T‐shaped microstrip line (MSL) integrated with variable gain common source TIA using MSL peaking technique and off‐chip post‐amplification integration is a newly proposed architecture to achieve a ultra‐low noise, high dynamic range (DR) and high figure of merit over broadband than a traditional TIAs. First, the integrated T‐shaped MSL develops an additional resonant frequency that resonates with a photodiode capacitance improving the bandwidth performance at higher Q values. Second, the shunt MSL peaking technique that introduces an additional conjugate pole‐pair that cancels the effect of input capacitance helps to further improve the bandwidth of the TIA. Finally, an active feedback concept achieves a wide linear dynamic range enabling high TIA detectability. The proposed TIA realizes an impedance bandwidth of 770 MHz ranging from 7.12 to 7.89 GHz with a transimpedance gain of 105.1 dBΩ and ultra‐low input‐referred noise (IRN) density of 2.71 pA/√Hz. A high linear DR of 70 dB is achieved by employing a variable gain control scheme with a low group delay variation of 0.81 ns. The proposed work demonstrates a 1‐Gb/s data rate while a bit‐error rate less than 10−12 is achieved. The TIA consumes a power of 0.82 mW under the supply voltage of 1.2 V.

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SummaryIn this brief, an X‐band quasi circulator (QC)‐integrated low‐noise amplifier (LNA) implemented in 65‐nm Complementary Metal Oxide Semiconductor (CMOS) technology is presented. This work is the first QC‐LNA for the X‐band to the author's best knowledge, which achieves 30‐dB flat gain in 8–12 GHz with only 0.5‐dB variation across the band. This QC‐LNA uses two‐stage current reused techniques with variable impedance load. QC provides the minimum insertion loss of 0.9 dB with good return and isolation losses. Statistical analysis is presented for QC‐LNA to predict the percentage error tolerance. Quasi‐Newton (QN) control algorithm is used to optimize the parameter of the whole design. The design of experiment (DoE) is performed to claim the contribution towards gain, return loss, and noise figure. The proposed LNA measurement provides a minimum NF of 1 dB at 9.5 GHz, which remains less than 1.4 dB across 8–12 GHz. The fabricated LNA works with a supply voltage of 1.2 V and is unconditionally stable across the frequency. The calculated chip area is 0.84 × 0.52 mm2. This QC‐LNA exhibits an input and output 1‐dB compression point (IP1dB and OP1dB) of −15 and +13.8 dBm, respectively. It also exhibits third‐order input and output intercept point (IIP3 and OIP3) of +10 dBm and of +40 dBm, respectively. The proposed QC‐LNA draws only 8.7 mA from 1.2 V.