INJECTION-LOCKED FREQUENCY DIVIDER AND PLL CIRCUIT

摘要

An injection locked frequency divider and a PLL circuit, having a wide operating frequency bandwidth and capable of reducing the influence of any parasitic capacitance, are provided. Injection locked frequency divider (100) includes ring oscillator 140 that cascade-connects first amplifier circuit (141) including N-channel MOS transistor (111) and P-channel MOS transistor (112), and second amplifier circuit 142 and third amplifier circuit (143) that have the same configuration as first amplifier circuit (141) in three stages in a ring; N-channel MOS transistor 150 in which the sources of N-channel MOS transistors (111, 121, 131) in the respective stages are connected to the drain thereof; and differential signal injection circuit (160) that injects injection signal 11 to the gates of P-channel MOS transistors (112, 122, 132) in the respective stages and injects a reverse phase signal of injection signal 11 as a differential signal to the gate of N-channel MOS transistor (150).