A transmission channel transmits high-voltage pulses and receives echos of the high-voltage pulses. The transmission channel includes a current generator circuit (104), which generates current-integrator drive currents, a receiver (108), which amplifies transducer-echo signals, and control circuitry (102). The control circuitry generates one or more control signals to control generation of current-integrator drive currents by the current generator circuit during transducer-driving periods and reception of transducer-echo signals by the receiver during echo-reception periods. A current integrator (106) integrates current-integrator drive currents generated by current generator circuit to generate transducer drive signals.