Signal processing circuit and measurement instrument

A measurement instrument comprising a signal processing circuit, the signal processing circuit comprising:

• a measurement input configured to receive an input signal;
• at least two parallel measurement channels connected to the measurement input such that the input signal received via the measurement input is forwarded to the two parallel measurement channels, wherein a first one of the at least two parallel measurement channels is configured to process the input signal, thereby generating a first complex-valued measurement signal, wherein a second one of the at least two parallel measurement channels is configured to process the input signal, thereby generating a second complex-valued measurement signal;
• and
• an analysis circuit configured to:
• determine a first error quantity associated with the first complex-valued measurement signal;
• determine a second error quantity associated with the second complex-valued measurement signal;
• determine a complex-valued average signal, wherein the complex-valued average signal corresponds to a combined average of the first complex-valued measurement signal and of a complex conjugate of the second complex-valued measurement signal;
• determine a combined error quantity based on the complex-valued average signal;
• and
• determine a comparison quantity based on the combined error quantity as well as based on the first error quantity and/or the second error quantity, wherein the comparison quantity is indicative of a relative magnitude of the combined error quantity compared to the first error quantity and/or the second error quantity, and wherein the comparison quantity is indicative of the amount of noise contributed by the at least two measurement channels in relation to the amount of noise contributed by the device under test.

A signal processing circuit for a measurement instrument, comprising:

• a measurement input configured to receive an input signal;
• at least two parallel measurement channels connected to the measurement input such that the input signal received via the measurement input is forwarded to the two parallel measurement channels, wherein a first one of the at least two parallel measurement channels is configured to process the input signal, thereby generating a first complex-valued measurement signal, wherein a second one of the at least two parallel measurement channels is configured to process the input signal, thereby generating a second complex-valued measurement signal;
• and
• an analysis circuit configured to:
• determine a first error quantity associated with the first complex-valued measurement signal;
• determine a second error quantity associated with the second complex-valued measurement signal;
• determine a complex-valued average signal, wherein the complex-valued average signal corresponds to a combined average of the first complex-valued measurement signal and of a complex conjugate of the second complex-valued measurement signal;
• determine a combined error quantity based on the complex-valued average signal;
• and
• determine a comparison quantity based on the combined error quantity as well as based on the first error quantity and/or the second error quantity, wherein the comparison quantity is indicative of a relative magnitude of the combined error quantity compared to the first error quantity and/or the second error quantity, and wherein the comparison quantity is indicative of the amount of noise contributed by the at least two measurement channels in relation to the amount of noise contributed by the device under test.