High-precision high-voltage current source circuit

Abstract

The invention discloses a high-precision high-voltage current source circuit. The high-precision high-voltage current source circuit comprises a logic control unit, a high-voltage Boost circuit, a negative pressure generation circuit, a DAC circuit, a high-voltage floating operation and amplification circuit, a constant-current source circuit, a bridge-H chopper circuit, and an overcurrent overload protection circuit. By adopting the high-precision high-voltage current source circuit, the problems of the traditional Howland current source that the stability is poor, the circuit is easy in saturation state, the output current is relatively low, the efficiency is relatively low, the influence of the operation and amplification Ibias is great, the four peripheral matching resistors are difficult in consistency and the like can be solved. The high-precision high-voltage current source circuit is capable of realizing the fine stepper adjustment for the current, large in current output range, high in load capacity, flexible and variable in circuit parameters and relatively low in requirement for the consistence of peripheral parameters.

Description

technical field [0001] The invention belongs to the field of electronic circuits and relates to a high-precision high-voltage current source circuit. Background technique [0002] Current sources, a vast field. The most basic current source circuit is a simple current source or a current mirror current source composed of triodes, see figure 1 ; After the popularization and application of integrated operational amplifier circuits, a constant current source circuit composed of operational amplifier units combined with resistors, namely the Howland current source, appeared. figure 2 , the circuit model provides guidance for the follow-up constant current source circuit based on the op amp topology. [0003] In addition to adding negative feedback, the Howland current source also has a positive feedback link. In the Howland current source, Rh3 and Rh4 form a negative feedback network, and the output is fed back to the inverting input terminal. The feedback coefficient is Rh4 / ...

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Problems solved by technology

[0007] The main problem of the Howland current source is: poor stability. If the RhL terminal is removed, the op amp will enter a saturated state. At this time, the originally designed circuit function will not be realized. The output current is low, the efficiency is low, and the bias of the op amp itself is affected by Ibias. It is also very large, and it is difficult for the four matching resistors on the periphery to be exactly the same

[0008] The current mirror current source depends on the Ib current of Qm1 on the left to maintain the stability of the Ib current of Qm2 on the right. When the base current Ib of the triode is constant, Rm3 is the load impedance. When the load resistance changes, such as increases, Rm3*Im2 becomes larger, the collector potential Uc of the Qm2 tube increases, and Uce=VCC-Uc of the Qm2 triode causes the potential between the Uce electrodes to decrease, which in turn leads to a change in the operating point of the circuit, resulting in a change in the Ic current, which in turn affects the constant current source circuit. output stability

At the same time, the temperature stability of the current mirror constant current source is poor, and the single-tube temperature rise of the Qm1 and Qm2 transistors can easily lead to distortion of the output characteristics

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