A circuit assembly includes an integrated circuit (IC) die and a capacitor die. The IC die has a first hybrid bonding layer. The capacitor die is stacked with the IC die, and is configured to include a capacitor coupled to the IC die, and has a second hybrid bonding layer in contact with the first hybrid bonding layer; wherein the IC die is electrically coupled to the capacitor die through the first hybrid bonding layer and the second hybrid bonding layer.