In some embodiments, the amount of high frequency peaking provided by circuit 121 may be varied by changing the effective input series impedance of the wire signals. In one particular further embodiment, each of the resistor/switch combinations 110 of FIG. 1 (one example being R1 and S1) are embodied as multiple paralleled sets of series resistors and switches as illustrated in FIG. 3. As one example offered without limitation, resistors R21 through R28 are each of value 8*R1, with each of switches S21 through S28 being a controllable MOS transistor switch. In this embodiment, enabling from one to eight of the collection of switches S21 through S28 produces eight distinct values of effective series resistance for the overall assembly 110, producing eight distinct high frequency peaking characteristics for the combined ENRZ subchannel detector. In a practical embodiment, each instance of 110 in FIG. 1 is replaced by an instance of FIG. 3; the number of switches closed in a given instance of FIG. 3 may be zero (to disconnect that input in the second or third operational modes, as subsequently described) or a predetermined value to provide the desired frequency characteristics associated with a determined impedance value. Adjustment of the resistor value to attenuate high-frequency signal may be useful in baud-rate clock data recovery (CDR) applications, and bandwidth may be reduced if channel loss is low. Since the front-end may be shared between the Rx and the Tx, the passive MIC may completely isolate Rx from Tx by disconnecting all switches, which may increase frequency response. In some embodiments, a secondary protection device composed of a diode and a resistor (often referred to as a charged device model (CDM) diode and resistor) used to protect the system from CDM failures may be replaced by a single CDM diode, which may increase the frequency response.