A ?NMR CMOS transceiver using a butterfly-coil input for integration with a digital microfluidic device inside a portable magnet

This paper reports a CMOS transceiver apt for integration with a digital microfluidic device, allowing electronic-automated sample management and measurement of micro-nuclear magnetic resonance (μNMR) signals inside a portable magnet. The transmitter (TX) employs an all-digital state control and a pulse sequence synthesizer to emit the exciting pulses for the samples. The receiver (RX) is led by a low-noise amplifier (LNA) using multi-stage NMOS-PMOS-complementary differential pairs, to achieve a sub-nV/√Hz input-referred noise. The RX baseband is a 6th-order Butterworth, dynamic-baseband-bandwidth lowpass filter (2.5 to 20 kHz), which suppresses the out-of-band noise and offers a fast recovery time between the exciting pulses, reducing the dead time of the RX for better sensitivity. Fabricated in 0.18-μm CMOS, the transceiver occupies a die area of 2.1 mm² and consumes 6.6/23.7 mW of power in the TX/RX mode.