The invention discloses an
inductance-
capacitance type
numerically controlled oscillator with high tuning precision. A resonant circuit comprises an
inductor L, a
capacitor C, a first
control unit circuit, ..., and a nth
control unit circuit, wherein the first
control unit circuit is controlled by a first control bit D1 and consists of P type
field effect transistors PM11, PM12, PM13 and PM14, the nth control unit circuit is controlled by a nth control bit Dn and consists of P type
field effect transistors PMn1, PMn2, PMn3 and PMn4, and the
inductor L, the
capacitor C, the first control unit circuit, ..., and the nth control unit circuit are connected in parallel to form a control unit array; a first input end of the
capacitor L is connected with a first input end of the capacitor C to be taken as a first input end (1) of the resonant circuit, and a second input end of the
inductor L is connected with a second input end of the capacitor C to be taken as a second input end (2) of the resonant circuit; and each control unit is formed by the reverse parallel connection of PMOS (Positive Channel
Metal Oxide Semiconductor) tube pairs with different sizes, the small
capacitance difference can be obtained by the
size difference of the PMOS tubes, and the fine frequency tuning step can be obtained, namely, the
high frequency tuning precision is realized.