Low Noise Transformer Input Pre-Amp Design - A Solution that Eliminates CMID
This paper examines more closely the advantages of input transformer-op amp configurations, especially those implemented in low-noise designs. Usual transformer input stage topology works in non-inverting architecture, since it allows the transformer to work with optimum loading, to maximize the signal-to-noise ratio. However, this configuration is subject to Common-Mode voltage Induced Distortion - CMID. The susceptibility is further increased if the amplifier source impedances is not perfectly matched. This is illustrated by tests on popular audio op amps. Advanced transformer input stage topology proposed in this work completely prevents this kind of distortion. Noise performance remains unaffected, yet listening tests in practical application confirm the sound to be more pleasant.
Click to purchase paper as a non-member or login as an AES member. If your company or school subscribes to the E-Library then switch to the institutional version. If you are not an AES member and would like to subscribe to the E-Library then Join the AES!
This paper costs $33 for non-members and is temporarily free for AES members.