Abstract: Various approaches of amplifying an NMR signal in response to a transmitted NMR pulse include estimating the characteristic time associated with the NMR signal; transmitting the NMR pulse to the sample and receiving the NMR signal therefrom; and applying a time-dependent amplifier gain to the received NMR signal based at least in part on the estimated characteristic time.

Abstract: Various approaches of adjusting a gain of received signals in integrated circuitry include implementing an open-loop source-degenerated amplifier having a pair of input devices for amplifying the received signals; boosting an effective transconductance of the input devices (e.g., using a pair of super-gm feedback loops); and setting a bias current of devices in the open-loop source-degenerated amplifier (e.g., using a constant-gm bias circuit).

Abstract: An approach for accurately setting a duty cycle of PA switching waveforms uses an all-digital PVT sensor circuit. In various embodiments, the all-digital PVT sensor circuit measures a pulse width of a periodic reference signal using digital delay line, and subsequently, implements an off-chip digital calculation to program the digital delay line to delay this periodic reference signal so that, when the delayed periodic reference signal is combined with the original (undelayed) reference via a logical AND operation, the resulting signal conforms to a desired duty cycle. In one implementation, the PA is a class-D PA, which may have a single-ended configuration or a differential configuration having two single-ended structures operating in opposite phases.

Abstract: Systems and methods for reducing variability in the output impedance of an integrated switch-mode power amplifier (PA) split the output impedance between passive resistor, which may be on-chip, and a MOSFET switch of the amplifier. The PA may have a single-ended configuration or a differential configuration having two single-ended structures operating with opposite phases. In one implementation, the size of the MOSFET switch is larger than that of the MOSFET switch implemented in a conventional PA, but the size is still acceptable to operate the PA at a desired frequency. In addition, a calibration approach may be utilized to ensure that the MOSFET switch has a controlled and calibrated ON resistance, thereby providing stable output power levels of the PA and ensuring consistency and repeatability in NMR measurements.

Abstract: Various approaches of amplifying an NMR signal in response to a transmitted NMR pulse include estimating the characteristic time associated with the NMR signal; transmitting the NMR pulse to the sample and receiving the NMR signal therefrom; and applying a time-dependent amplifier gain to the received NMR signal based at least in part on the estimated characteristic time.

Abstract: Various approaches of receiving signals in integrated circuitry include implementing two successive stages of signal manipulation and employing an interface having an AC coupling network and buffer circuits for decoupling the output impedance and common-mode level of the first stage of signal manipulation from the input impedance and common-mode level of the second stage of signal manipulation without degrading the performance of either stage.

Abstract: Various approaches of receiving signals in integrated circuitry include implementing a voltage-mode passive mixer for down-converting the frequency of the received signals, a baseband output buffer, and a transconductance amplifier coupled between the voltage-mode passive mixer and baseband output buffer for presenting a high-impedance load to the voltage-mode passive mixer and shielding the baseband output buffer from a high-frequency feedthrough.