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My main concern would be that each VCC via will produce an antipad in the ground plane, making the geometry asymmetric.

Ideally the traces in the differential pair only interact with each other, as another answer said. But practically (especially in a dense design like your example), they also interact with surrounding conductors, and the coplanar ground, or ground beneath a differential microstrip will affect the characteristic impedance. And discontinuities in the ground will cause reflections and/or mode conversion in the propagating signals.

So one trace having ground directly beneath it, and the other having ground with periodic gaps due to the VCC vias, is likely to produce undesirable results, such as a different characteristic impedance than expected or differential-to-single-modeended signal conversion.

I'd try to find an alternative geometry. Either differential microstrip, or coplanar with ground on both sides.

I believe both of the examples you showed from Analog Devices documentation show CPWG with ground on both sides. Neither one shows a power net being used as ground like you propose.

My main concern would be that each VCC via will produce an antipad in the ground plane, making the geometry asymmetric.

Ideally the traces in the differential pair only interact with each other, as another answer said. But practically, they also interact with surrounding conductors, and the coplanar ground, or ground beneath a differential microstrip will affect the characteristic impedance.

So one trace having ground directly beneath it, and the other having ground with periodic gaps due to the VCC vias, is likely to produce undesirable results, such as a different characteristic impedance than expected or differential-to-single-mode signal conversion.

I'd try to find an alternative geometry. Either differential microstrip, or coplanar with ground on both sides.

My main concern would be that each VCC via will produce an antipad in the ground plane, making the geometry asymmetric.

Ideally the traces in the differential pair only interact with each other, as another answer said. But practically (especially in a dense design like your example), they also interact with surrounding conductors, and the coplanar ground, or ground beneath a differential microstrip will affect the characteristic impedance. And discontinuities in the ground will cause reflections and/or mode conversion in the propagating signals.

So one trace having ground directly beneath it, and the other having ground with periodic gaps due to the VCC vias, is likely to produce undesirable results, such as a different characteristic impedance than expected or differential-to-single-ended signal conversion.

I'd try to find an alternative geometry. Either differential microstrip, or coplanar with ground on both sides.

I believe both of the examples you showed from Analog Devices documentation show CPWG with ground on both sides. Neither one shows a power net being used as ground like you propose.

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source | link

My main concern would be that each VCC via will produce an antipad in the ground plane, making the geometry asymmetric.

Ideally the traces in the differential pair only interact with each other, as another answer said. But practically, they also interact with surrounding conductors, and the coplanar ground, or ground beneath a differential microstrip will affect the characteristic impedance.

So one trace having ground directly beneath it, and the other having ground with periodic gaps due to the VCC vias, is likely to produce undesirable results, such as a different characteristic impedance than expected or differential-to-single-mode signal conversion.

I'd try to find an alternative geometry. Either differential microstrip, or coplanar with ground on both sides.