Inductive current detection circuit for power management chip

Abstract

The invention discloses an inductive current detection circuit for a power management chip. The inductive current detection circuit comprises a biasing circuit, a pre-amplification stage circuit, a second amplification stage circuit, a third amplification stage circuit and an output stage circuit. A triode Q1 and a triode Q3 as well as a triode Q2 and a triode Q4 are adopted to form Darlington input tubes respectively, so that the input offset voltage of the pre-amplification stage circuit is reduced; the technology of a transmission gate T1, a transmission gate T2, a transmission gate T3 and a transmission gate T4 is adopted, and the opening of the four transmission gates is determined by the current direction of an external inductor, so that the double-end input and single-end output of the second amplification stage circuit are realized; meanwhile, the third amplification stage circuit, the pre-amplification stage circuit and the second amplification stage circuit are adopted to form a negative feedback system, and the technology of sampling an external inductive current signal is adopted, so that the sampling precision of the circuit on the inductive current is improved; therefore, a detection signal for the inductive current of the power management chip is generated at the output end VOUT of the output stage circuit.

Description

technical field [0001] The invention belongs to the technical field of microelectronics, and in particular relates to an inductor current detection circuit for a power management chip. Background technique [0002] DC-DC switching power supply chips have been widely used in portable electronic devices due to their high conversion efficiency. As a basic module of the power management chip, the current detection circuit is mainly used to detect the current on some components or a branch, and the detected signal is fed back to the system for control and protection circuits. [0003] figure 1 It is a traditional inductor current detection circuit, mainly composed of NMOS transistor M1, NMOS transistor M2, NMOS transistor M3, PMOS transistor M4, PMOS transistor M5, resistor R1, resistor R2 and amplifier AMP. Low frequency gain A of amplifier AMP d >>1 and form a negative feedback connection to force the voltages of the two input terminals of the amplifier to be equal, th...

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Problems solved by technology

[0004] figure 1 The traditional inductor current detection circuit shown has high requirements on the input offset voltage of the amplifier AMP, and the traditional amplifier AMP has a high input offset voltage, which will affect the detection accuracy of the current detection circuit, thus restricting the application of the inductor current detection circuit in high-precision systems. application in

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