A Transconductance Amplifier Based on Self-biased Cascode Structure

Abstract

The present invention provides a transconductance amplifier based on a self-biased cascode structure, which includes a self-biased cascode input stage structure composed of PMOS input transistors M1, M2, M3 and M4, and NMOS transistors M5, M6 and M7 The self-biased cascode first-stage load structure composed of M8, the second-stage common-source amplifier structure composed of NMOS transistor M9 and PMOS transistor M10, the bias circuit structure composed of NMOS transistors M11, M12 and PMOS transistor M13, The amplifier compensation capacitor CC, the amplifier load capacitor CL, the reference current source Iref and the PMOS transistor M0 that provides the constant current source function. The invention also provides a self-biased cascode transconductance amplifier using an NMOS transistor as an input transistor. Both the input tube and the load tube of the first-stage amplifier of the present invention adopt a self-biased cascode structure, which improves the output impedance of the first-stage amplifier and increases the DC gain of the first-stage amplifier; the MOS of the first-stage amplifier The substrate voltage of the tube is provided by the amplifier bias circuit; the connection mode of the compensation capacitor Cc realizes a higher quality factor.

Description

technical field [0001] The invention belongs to the technical field of analog or digital-analog hybrid integrated circuits, and in particular relates to a transconductance amplifier based on a self-biased cascode structure. Background technique [0002] In recent years, with the continuous development of integrated circuit manufacturing technology, the demand for low-power analog integrated circuits has gradually increased. In order to meet the requirements of low power consumption, the power supply voltage has been further reduced. In response to this trend, in order to ensure the performance of the amplifier, some structures have been developed to increase the gain of the transconductance amplifier, among which the self-biased cascode structure is one. Under this structure, by adjusting the substrate voltage of the MOS transistor, the threshold voltage of the MOS transistor is changed, thereby changing the transconductance and output impedance of the MOS transistor, so tha...

AI Technical Summary

Problems solved by technology

However, the inventors of the present application found that figure 2 The circuit structure shown requires special use of low-threshold transistors, or provides a bias voltage VCM, which will increase the complexity of the process or circuit; on the other hand, figure 2 The amplifier structure shown still adopts RC compensation method, and its compensation effect is limited

Images