LOOP FILTER FOR IMPROVING PHASE NOISE

摘要

PURPOSE: A loop filter for improving a phase noise is provided to improve the phase noise by changing a lock time. CONSTITUTION: The first capacitor(C1) is connected between an output terminal of a PLL(Phase Locked Loop) IC and a ground terminal. The second capacitor(C2) and the second resistance(R2) are connected in parallel to the first capacitor(C1). The third resistance(R3) is connected between an output terminal of the PLL IC and an input terminal of a VCO. The third capacitor(C3) is connected between the input terminal of the VCO and the ground terminal. The fourth resistance(R4) is connected with a control port of a micro computer and a common connection point between the second capacitor(C2) and the second resistance(R2). The fourth capacitor(C4) is connected with the common connection point between the second capacitor(C2) and the second resistance(R2) and the ground terminal. The fifth resistance(R5) is connected with a CDMA/AMPS control port of a micro computer and the common connection point between the second capacitor(C2) and the second resistance(R2).