Abstract: A circuit, system and method for measuring the optimal frequency of transmission and reception for achieving the best possible signal-to-noise ratio (SNR) in low impedance receive systems are provided. In one embodiment, the circuit includes: (1) an antenna that transmits and receives radio-frequency (RF) signals, (2) a receive circuit that is connected to the antenna during a receive mode and a calibration mode, wherein the receive circuit includes an amplifier having a low input impedance, and (3) an impedance switching circuit that places the amplifier in a high input impedance state during the calibration mode.

Abstract: A circuit, system and method for measuring the optimal frequency of transmission and reception for achieving the best possible signal-to-noise ratio (SNR) in low impedance receive systems are provided. In one embodiment, the circuit includes: (1) an antenna that transmits and receives radio-frequency (RF) signals, (2) a receive circuit that is connected to the antenna during a receive mode and a calibration mode, wherein the receive circuit includes an amplifier having a low input impedance, and (3) an impedance switching circuit that places the amplifier in a high input impedance state during the calibration mode.

Abstract: Circuits including a low noise amplifier (LNA) configured to receive a radio-frequency (RF) that include an input transistor to receive a waveform control signal at a gate terminal are provided. The circuits include a control transistor configured to receive a gate signal from a source terminal in the input transistor when the waveform control signal is high and to discharge the gate signal into a current sink coupled to ground when the waveform control signal is low at a controlled rate based on a resistor-capacitor (RC) network and a changing gain of the control transistor. The circuits include a buffer and a dump transistor to connect the critical resistor for optimal damping to the input of LNA when the dump transistor is ‘on’ and disconnect when the dump transistor if off. Systems and methods for use in an NMR sensor including a circuit as above are also provided.

Abstract: Circuits including a low noise amplifier (LNA) configured to receive a radio-frequency (RF) that include an input transistor to receive a waveform control signal at a gate terminal are provided. The circuits include a control transistor configured to receive a gate signal from a source terminal in the input transistor when the waveform control signal is high and to discharge the gate signal into a current sink coupled to ground when the waveform control signal is low at a controlled rate based on a resistor-capacitor (RC) network and a changing gain of the control transistor. The circuits include a buffer and a dump transistor to connect the critical resistor for optimal damping to the input of LNA when the dump transistor is ‘on’ and disconnect when the dump transistor if off. Systems and methods for use in an NMR sensor including a circuit as above are also provided.

Abstract: Various driver circuit apparatuses and methods for driving an electrical signal are disclosed herein. For example, some embodiments provide a driver circuit including a controlled-slew rate input circuit, a buffer that is connected to the controlled-slew rate input circuit, and an output driver that is connected to the buffer. The driver circuit is adapted to drive an output signal from the output driver based on an input signal to the controlled-slew rate input circuit. The impedance at the input of the output driver is lower than the impedance at the output of the controlled-slew rate input circuit.