This application discloses a hard disk drive, a head stack assembly, and a printed circuit board configured to include impedance patches on the flex ground plane, the flex power plane, the printed circuit ground plane and/or the printed circuit power plane over or under a connector site in the disk base that conveys access read and write differential signals for the sliders' access of rotating disk surfaces. These impedance patches minimize impedance discontinuities in the read and/or write differential signals through the connector site, which may improve the ability of the hard disk drive to transmit these signals at higher frequencies.