| 摘要 |
A circuit for alternately providing a first frequency to a receiver stage (20) and a second frequency to a transmitter stage (25) of a transmitter and receive circuit (11). The circuit comprises an oscillator (38), a first switch (33), a second switch (42), and a control circuit (29). The first switch (33) couples information to the oscillator (38) to be transposed on the second frequency during transmission. The second switch (42) couples the oscillator (38) to either the transmitter stage (25) or the receiver stage (20). Prior to changing oscillator frequency the control circuit (29) disables both outputs of the second switch (42). The control circuit (29) alternately tunes the oscillator (38) to the first frequency and enables the second switch (42) such that the oscillator (38) is coupled to the receiver stage (20) and tunes the oscillator (38) to the second frequency, enables the first switch (33), and enables the second switch (42 ) such that the oscillator (38) is coupled to the transmitter stage (25).
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