a single integrated chip has first and second voltage controlled oscillators and first and second buffers . the first voltage controlled oscillator has a first output defined by a first frequency band , and the second voltage controlled oscillator has a second output defined by a second frequency band . the first and second buffers selectively couple the first and second outputs to a common output . the first buffer is coupled between the first frequency controlled oscillator and the common output , and the second buffer is coupled between the second frequency controlled oscillator and the common output . the first buffer has a high output impedance when the second buffer couples the second output to the common output , and the second buffer has a high output impedance when the first buffer couples the first output to the common output .