Voltage-mode filters with output impedance neutralization

A device, comprising:

• a digital-to-analog converter circuit comprising an output interface configured to generate a differential analog voltage signal comprising a first voltage signal and a second voltage signal which are complementary voltage signals;
• a differential voltage-mode filter circuit configured to filter the differential analog voltage signal and output a filtered differential analog voltage signal comprising a first filtered voltage signal and a second filtered voltage signal which are complementary filtered voltage signals;
• and
• a current-mode output circuit, coupled to the differential voltage-mode filter circuit, and configured to convert the first filtered voltage signal and the second filtered voltage signal into a first current signal and a second current signal, respectively, for processing by the current-mode output circuit;
• wherein the differential voltage-mode filter circuit comprises a first voltage-mode filter circuit configured to filter the first voltage signal, a second voltage-mode filter circuit configured to filter the second voltage signal, and a neutralization network comprising a first neutralization impedance circuit and a second neutralization impedance circuit;
• wherein the first voltage-mode filter circuit and the second voltage-mode filter circuit each comprise a unity gain buffer having a nonzero output impedance;
• wherein the first neutralization impedance circuit couples an input node of the first voltage-mode filter circuit to an output node of the second voltage-mode filter circuit, and the second neutralization impedance circuit couples an input node of the second voltage-mode filter circuit to an output node of the first voltage-mode filter circuit;
• and
• wherein the neutralization network is configured to correct a frequency response of each of the first voltage-mode filter circuit and the second voltage-mode filter circuit by at least one of cancelling and compensating for at least one transmission zero of a transfer function of each of the first voltage-mode filter circuit and the second voltage-mode filter circuit, which results from the nonzero output impedance of the respective unity gain buffers.

A system, comprising:

• a radio frequency signal generator which is configured to convert a baseband signal to a radio frequency signal, the radio frequency signal generator comprising:
• a digital-to-analog converter circuit comprising an output interface configured to generate a differential baseband voltage signal comprising a first baseband voltage signal and a second baseband voltage signal which are complementary baseband voltage signals;
• a differential voltage-mode filter circuit configured to filter the differential baseband voltage signal and output a filtered differential baseband voltage signal comprising a first filtered baseband voltage signal and a second filtered baseband voltage signal which are complementary filtered baseband voltage signals;
• and
• a current-mode radio frequency output circuit, coupled to the differential voltage-mode filter circuit, and configured to convert the first filtered baseband voltage signal and the second filtered baseband voltage signal into a first baseband current signal and a second baseband current signal, respectively, for processing by the current-mode radio frequency output circuit to generate the radio frequency signal;
• wherein the differential voltage-mode filter circuit comprises a first voltage-mode filter circuit configured to filter the first baseband voltage signal, a second voltage-mode filter circuit configured to filter the second baseband voltage signal, and a neutralization network comprising a first neutralization impedance circuit and a second neutralization impedance circuit;
• wherein the first voltage-mode filter circuit and the second voltage-mode filter circuit each comprise a unity gain buffer having a nonzero output impedance;
• wherein the first neutralization impedance circuit couples an input node of the first voltage-mode filter circuit to an output node of the second voltage-mode filter circuit, and the second neutralization impedance circuit couples an input node of the second voltage-mode filter circuit to an output node of the first voltage-mode filter circuit;
• and
• wherein the neutralization network is configured to correct a frequency response of each of the first voltage-mode filter circuit and the second voltage-mode filter circuit by at least one of cancelling and compensating for at least one transmission zero of a transfer function of each of the first voltage-mode filter circuit and the second voltage-mode filter circuit, which results from the nonzero output impedance of the respective unity gain buffers.

A system, comprising:

• a quantum processor comprising at least one superconducting quantum bit;
• an arbitrary waveform generator comprising at least one arbitrary waveform generator channel configured to convert a baseband signal to a radio frequency control pulse which controls the at least one superconducting quantum bit, wherein the at least one arbitrary waveform generator channel comprises:
• a digital-to-analog converter circuit comprising an output interface configured to generate a differential baseband voltage signal comprising a first baseband voltage signal and a second baseband voltage signal which are complementary baseband voltage signals;
• a differential voltage-mode filter circuit configured to filter the differential baseband voltage signal and output a filtered differential baseband voltage signal comprising a first filtered baseband voltage signal and a second filtered baseband voltage signal which are complementary filtered baseband voltage signals;
• and
• a current-mode radio frequency output circuit, coupled to the differential voltage-mode filter circuit, and configured to convert the first filtered baseband voltage signal and the second filtered baseband voltage signal into a first baseband current signal and a second baseband current signal, respectively, for processing by the current-mode radio frequency output circuit to generate the radio frequency control pulse;
• wherein the differential voltage-mode filter circuit comprises a first voltage-mode filter circuit configured to filter the first baseband voltage signal, a second voltage-mode filter circuit configured to filter the second baseband voltage signal, and a neutralization network comprising a first neutralization impedance circuit and a second neutralization impedance circuit;
• wherein the first voltage-mode filter circuit and the second voltage-mode filter circuit each comprise a unity gain buffer having a nonzero output impedance;
• wherein the first neutralization impedance circuit couples an input node of the first voltage-mode filter circuit to an output node of the second voltage-mode filter circuit, and the second neutralization impedance circuit couples an input node of the second voltage-mode filter circuit to an output node of the first voltage-mode filter circuit;
• and
• wherein the neutralization network is configured to correct a frequency response of each of the first voltage-mode filter circuit and the second voltage-mode filter circuit by at least one of cancelling and compensating for at least one transmission zero of a transfer function of each of the first voltage-mode filter circuit and the second voltage-mode filter circuit, which results from the nonzero output impedance of the respective unity gain buffers.