An Inductorless Wideband Gm-boosted Balun LNA with nMOS-pMOS Configuration and Capacitively Coupled Loads for sub-GHz IoT Applications
Abstract : This brief presents an inductorless gm-boosted wideband balun low noise amplifier (LNA) for low power sub-GHz IoT applications. The proposed common source (CS) -common gate (CG) based gm-boosted balun LNA uses nMOS-pMOS configuration for doubling the transconductance and gain efficiency. Loads of CS and CG stages are capacitively coupled to remove the tradeoff between voltage gain and voltage headroom. In addition to this, the circuit employs noise cancelation using the CS-CG pair. The LNA is implemented in 0.18 µm RFCMOS process, which achieves a maximum voltage gain of 19.6 dB with a minimum noise figure (NF) of 3.6 dB. The 3-dB bandwidth ranges from 0.13 GHz to 0.93 GHz. The minimum IIP3 and IIP2 measured are -8.5 dBm and 12 dBm, respectively. The LNA core area is 0.18 mm2 and dissipates a total power of 3 mW from 1.8 V power supply.
? To improve an existing LNA design, differential noise reduction techniques, such as capacitive cross coupling, resistive feed through and Gm-boosted CG topology can be applied.
? At all other frequencies, the matching becomes progressively worse and eventually non-existent.
? When complex impedances are present, especially with parastitics, the two fundamental techniques in designing matching networks are absorption and resonance.
? The quarter-wave transformer can be used to match a real load impedance to a transmission line.
? Single or multiple sections of quarter-wave transformer designs can be adopted to present optimum matching characteristics over a desired frequency band.
? The problem of interference removal has been studied extensively in the past in various contexts, including background noise reduction in acoustic systems.
? However, in such device, the design of a fully on-chip CMOS wideband receiver front-end that can process several radar/satellite signal simultaneously becomes a multifold complex problem.
? To overcome these issues, appropriate circuit techniques using passive components need to be incorporated.
? The large out-of-band blockers may only be eliminated through front-end filtering otherwise it effects serious issues on receiver.
? The main issue concerning the broadband amplifier topologies is their inferior noise performance and wide band input matching for radio applications.
• It was proposed to add a shunt inductor with a large bypass capacitor to eliminate the adverse effect by resonance .
• In addition, a transformer feedbacked capacitor neutralizer was proposed to boost the gain of an LNA.
• A single-to-differential topology with resistive feedback was proposed to increase the loop gain by double as compared to that of the conventional single-ended resistive feedback LNA through a source follower.
• Minor changes were proposed in the process to lengthen the bulk lifetime, among which fully depleted silicon on insulator (FD-SOI) is promising to scale down to 11 nm.
? The primary focus of this research work is the development of a CMOS high-performance low noise wideband receiver architecture with a subthreshold out of band sensing receiver.
? High performance low noise, bandwidth extensive Main path receiver has been designed, simulated and fabricated in 65nm CMOS and verified by measurements.
? Blocker effects on various performance parameter like gain compression, DC offset, phase noise mixing, self mixing, sensitivity, IMD3/XMD of receiver, how it is impacting on various parameter of wireless front-end receiver.
? A new approach is presented to reject out of band blocker by using a multipath scheme or auxiliary path receiver without effecting the performance of main path receiver.
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