The invention provides a circuit, a communication unit for VCO frequency adjustment and a frequency generation method. The circuit comprises a frequency generation circuit comprising a phase locked loop, PLL, arranged to generate a carrier frequency; and a controller operably coupled to the frequency generation circuit and arranged to determine a frequency location of one or more signals output by the frequency generation circuit and provide a control signal thereto to adjust the carrier frequency generated by the frequency generation circuit. The controller is arranged to: cooperate with the PLL to introduce a frequency offset in the generated carrier frequency in a first frequency direction; and introduce a compensating frequency offset in a baseband transmit signal in a second frequency direction opposite to the first frequency direction. According to the invention, a need to implement a harmonic rejection mixer and associated LO phase shifting circuits is avoided, and a reduced die area (circuit area) and/or current consumption is facilitated.