abcyin
Full Member level 4
Hi, all
I am designing a FSK modulator, using the scheme that changing the VCO output frequency to represent the baseband data. In theory, the VCO in the PLL loop will be locked at first, and then when the baseband starts transmit data, the PLL will operate in open loop mode, and the VCO output frequency will be modulated, to fc+delta(f) or fc-delta(f), but there is a problem, how can I realize the fc+delta(f) and fc-delta(f) in the same circuit?
thanks in advance!
I am designing a FSK modulator, using the scheme that changing the VCO output frequency to represent the baseband data. In theory, the VCO in the PLL loop will be locked at first, and then when the baseband starts transmit data, the PLL will operate in open loop mode, and the VCO output frequency will be modulated, to fc+delta(f) or fc-delta(f), but there is a problem, how can I realize the fc+delta(f) and fc-delta(f) in the same circuit?
thanks in advance!