Certain aspects of the present disclosure provide fully differential phase detectors for use in delay-locked loops, for example. One example phase detecting circuit generally includes a first input for a reference signal; a second input for an input signal to be compared with the reference signal; a set-reset (S-R) latch having a set input, a reset input, a first output, and a second output, and a delay (D) flip-flop having a logic input, a clock input, a reset input, and a logic output. The first input is connected with S-R reset input, the second input is connected with S-R set input, the first S-R output is connected with the D clock input, and the second S-R output is connected with the D reset input. The logic output of the D flip-flop indicates whether the input signal is leading or lagging the reference signal.