A resistivity imager for a formation traversed by a borehole, the imager comprising: pulse generation circuitry configured to generate a plurality of discrete energy pulses; characterized in that: the pulse generation circuitry comprises a reactive component configured to selectively couple to a power source to generate the discrete energy pulses, wherein the pulse generation circuitry forms, when in operation, a resonant circuit with the formation and any intervening mud disposed in the borehole; and wherein the pulse generation circuitry has an operating frequency and is configured to automatically adjust the operating frequency to an optimum value in response to the resonant circuit formed; and the imager further comprises: an array configured to rotate in the borehole and having electrodes (112, 114, 116), the electrodes (112, 114, 116) coupled to the reactive component and configured to be exposed to the formation in the borehole, one or more of the electrodes (112, 114, 116) configured to discharge the discrete energy pulses into the formation while the array is rotating and being subjected to impedances (Z1, Z2, Z3) in response thereto; measurement circuitry operatively coupled between the reactive component and the array and configured to measure discharges of the discrete energy pulses subjected to the impedances (Z1, Z2, Z3); and control circuitry configured to process the measured discharges and to determine parameters indicative of resistivity of the formation based on the processed discharges. pulse generation circuitry configured to generate a plurality of discrete energy pulses; characterized in that: the pulse generation circuitry comprises a reactive component configured to selectively couple to a power source to generate the discrete energy pulses, wherein the pulse generation circuitry forms, when in operation, a resonant circuit with the formation and any intervening mud disposed in the borehole; and wherein the pulse generation circuitry has an operating frequency and is configured to automatically adjust the operating frequency to an optimum value in response to the resonant circuit formed; and the pulse generation circuitry comprises a reactive component configured to selectively couple to a power source to generate the discrete energy pulses, wherein the pulse generation circuitry forms, when in operation, a resonant circuit with the formation and any intervening mud disposed in the borehole; and wherein the pulse generation circuitry has an operating frequency and is configured to automatically adjust the operating frequency to an optimum value in response to the resonant circuit formed; and the imager further comprises: an array configured to rotate in the borehole and having electrodes (112, 114, 116), the electrodes (112, 114, 116) coupled to the reactive component and configured to be exposed to the formation in the borehole, one or more of the electrodes (112, 114, 116) configured to discharge the discrete energy pulses into the formation while the array is rotating and being subjected to impedances (Z1, Z2, Z3) in response thereto; measurement circuitry operatively coupled between the reactive component and the array and configured to measure discharges of the discrete energy pulses subjected to the impedances (Z1, Z2, Z3); and control circuitry configured to process the measured discharges and to determine parameters indicative of resistivity of the formation based on the processed discharges. an array configured to rotate in the borehole and having electrodes (112, 114, 116), the electrodes (112, 114, 116) coupled to the reactive component and configured to be exposed to the formation in the borehole, one or more of the electrodes (112, 114, 116) configured to discharge the discrete energy pulses into the formation while the array is rotating and being subjected to impedances (Z1, Z2, Z3) in response thereto; measurement circuitry operatively coupled between the reactive component and the array and configured to measure discharges of the discrete energy pulses subjected to the impedances (Z1, Z2, Z3); and control circuitry configured to process the measured discharges and to determine parameters indicative of resistivity of the formation based on the processed discharges.