High-linearity transconductance circuit

Abstract

The invention provides a high-linearity transconductance circuit, and the circuit comprises a differential input stage circuit which converts an input voltage signal into a current signal; an IM2 injection circuit which is used for realizing direct current coupling injection of IM2 and comprises a first PMOS transistor M4, a second PMOS transistor M5, a third PMOS transistor M7 and a first resistor R1, wherein the feedback loop is used for forming negative feedback and comprises a fourth PMOS transistor M6, a fifth PMOS transistor M8, a second resistor R2 and an operational amplifier OP. According to the invention, IM2 direct current injection is adopted, so that the frequency interval of the double Tones can be expanded to be near the direct current, the injection position of the IM2 is changed from the grid electrode of the tail current tube to the grid electrode of the common-grid input differential pair tube, the IM3 item offset effect is obviously improved, the IIP3 performance of the circuit is greatly improved, and the anti-interference performance of the receiver is improved.

Description

technical field [0001] The present disclosure relates to the technical field of integrated circuits, in particular to a high linear transconductance circuit. Background technique [0002] In wireless receiving applications, the input RF signal is often accompanied by large interfering signals. These interference signals will eventually affect the normal reception of the target signal through the nonlinear effect of the receiving channel. [0003] When two adjacent interferences pass through a nonlinear system, the output will contain some components that do not belong to the harmonics of the input frequency, which is called intermodulation (IM). The intermodulation term produced by the second-order nonlinearity is called the second-order intermodulation term (IM 2 ); the intermodulation term generated by the third-order nonlinearity is called the third-order intermodulation term (IM 3 ). [0004] Third-order intermodulation (IM 3 ) is often the most common and serious i...

AI Technical Summary

Problems solved by technology

[0006] There are three deficiencies in this circuit structure: (1) IM 2 by C and R b AC coupled to M 3 tube gate, resulting in low frequency IM 2 item could not be injected

That is, when the frequency difference of the input dual tone is small, the IM generated by it 3 Items cannot be offset; (2) C and R b The resulting high-pass filter introduces additional phase shift, affecting the IM 3 Offset; (3)M 1 and M 2 The tube adopts grid input, it is difficult to achieve broadband power matching

Images