A circuit for subharmonic detection includes in-phase and quadrature mixers, first and second filters, and a processing circuit. The in-phase mixer has a first mixer input and a first mixer output. The quadrature mixer has a second mixer input and a second mixer output, the first mixer input coupled to the second mixer input. The first filter circuit has a first filter input and a first filter output, the first filter input coupled to the first mixer output. The second filter circuit has a second filter input and a second filter output, the second filter input coupled to the second mixer output. The processing circuit has a first input and a second input, the first input of the processing circuit coupled to the first filter output, the second input of the processing circuit coupled to the second filter output. The processing circuit is configured to detect a subharmonic component of a wave at the first mixer input and the second mixer input using a first direct current (DC) component at the first input of the processing circuit and a second DC component at the second input of the processing circuit.