Journal: Journal of magnetic resonance (San Diego, Calif. : 1997)

Article Title: DAC-board based X-band EPR spectrometer with arbitrary waveform control

doi: 10.1016/j.jmr.2013.07.015

Figure Lengend Snippet: Schematic overview of the pulsed AWG X-band EPR spectrometer. X-band microwave paths, indicated in red, transmit the pulse waveforms and carry the returning signal via coaxial cables, except for components #11, #13, #14, and #17, which are X-band waveguide components. The microwave carrier is generated (#2) and amplified (#3) and then mixed (#6) with two digitally controlled, quadrature 1 GHz transmit waveforms that are generated by the DAC board (#4) and amplified by two differential amplifiers (#5) to generate shaped X-band pulses at −10 dBm. The output waveform is filtered (#7), amplified to ~43 dBm (#10), and sent to the resonator (#12). The returning signal is power-limited (#15), and amplified (#16), before being sent to a heterodyne detector comprising an IQ mixer (#18) that generates two quadrature 1 GHz intermediate frequency (IF) waveforms, which are amplified (#19) and detected by the storage oscilloscope (#20). DC to 1 GHz signal paths are shown in blue and are present in both the AWG unit and the heterodyne detector. The reference oscillator (#21) is connected to a distribution amplifier (#22) and supplies a 10 MHz signal, shown in green, which synchronizes the microwave source, DAC board, and detector. Appendix A describes the various labeled components in detail. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Article Snippet: The AWG unit is comprised of a two-channel 1 GHz DAC board (High Speed Circuit Consultants, software build 10, – #4), [ 36 ] four Gaussian filters (High Speed Circuit Consultants) that reduce output noise, two differential amplifiers ( – #5) that drive the I and Q channels of an IQ mixer (Marki Microwave IQ-0618, – #6), a low pass filter (Marki Microwave FLP-1250, – #7) that suppresses harmonics generated by the IQ mixer, and a directional coupler ( – #8) that allows monitoring of the shaped microwave output of the AWG unit with 10 dB of attenuation on a sampling oscilloscope (Tektronix 11801C, – #9) with two sampling heads (Tektronix SD 24, Tektronix SD 22), as described in Appendix D . Additionally, each of the two differential amplifiers has a secondary output that can be monitored on a standard digital storage oscilloscope.

Techniques: Generated, Amplification, Labeling

Journal: Journal of magnetic resonance (San Diego, Calif. : 1997)

Article Title: DAC-board based X-band EPR spectrometer with arbitrary waveform control

doi: 10.1016/j.jmr.2013.07.015

Figure Lengend Snippet: Captured pulse sequence with multiple shaped pulses. Real (a) and imaginary (b) components of a targeted waveform (black dashed lines) are compared to the microwave waveform captured on the sampling oscilloscope (gray, solid lines) following the procedures described in Appendices C.1, C.2, and D. The target waveform consists of a sequence of composite pulses, a triangular pulse, a Gaussian pulse, a truncated sinc pulse, and a sech/tanh adiabatic rapid passage (left to right, respectively).

Article Snippet: The AWG unit is comprised of a two-channel 1 GHz DAC board (High Speed Circuit Consultants, software build 10, – #4), [ 36 ] four Gaussian filters (High Speed Circuit Consultants) that reduce output noise, two differential amplifiers ( – #5) that drive the I and Q channels of an IQ mixer (Marki Microwave IQ-0618, – #6), a low pass filter (Marki Microwave FLP-1250, – #7) that suppresses harmonics generated by the IQ mixer, and a directional coupler ( – #8) that allows monitoring of the shaped microwave output of the AWG unit with 10 dB of attenuation on a sampling oscilloscope (Tektronix 11801C, – #9) with two sampling heads (Tektronix SD 24, Tektronix SD 22), as described in Appendix D . Additionally, each of the two differential amplifiers has a secondary output that can be monitored on a standard digital storage oscilloscope.

Techniques: Sequencing, Sampling

Journal: Journal of magnetic resonance (San Diego, Calif. : 1997)

Article Title: DAC-board based X-band EPR spectrometer with arbitrary waveform control

doi: 10.1016/j.jmr.2013.07.015

Figure Lengend Snippet: Pulse sequence showing delays that are defined with ≤250 ps time resolution. The pulse sequence (a) consists of two 2 ns wide pulses with a varying inter-pulse delay of 6 ns, 6.25 ns, 6.5 ns, and 7 ns and generates a microwave waveform (b) that is captured on the sampling oscilloscope (as described in Appendix D) and digitally filtered with a 1 GHz bandpass. As the higher resolution inset (c) shows, delays with ≤250 ps resolution are generated with high fidelity.

Article Snippet: The AWG unit is comprised of a two-channel 1 GHz DAC board (High Speed Circuit Consultants, software build 10, – #4), [ 36 ] four Gaussian filters (High Speed Circuit Consultants) that reduce output noise, two differential amplifiers ( – #5) that drive the I and Q channels of an IQ mixer (Marki Microwave IQ-0618, – #6), a low pass filter (Marki Microwave FLP-1250, – #7) that suppresses harmonics generated by the IQ mixer, and a directional coupler ( – #8) that allows monitoring of the shaped microwave output of the AWG unit with 10 dB of attenuation on a sampling oscilloscope (Tektronix 11801C, – #9) with two sampling heads (Tektronix SD 24, Tektronix SD 22), as described in Appendix D . Additionally, each of the two differential amplifiers has a secondary output that can be monitored on a standard digital storage oscilloscope.

Techniques: Sequencing, Sampling, Generated