CN110086436B

CN110086436B - High-frequency broadband amplifier

Info

Publication number: CN110086436B
Application number: CN201910386522.2A
Authority: CN
Inventors: 黄颋; 李彧
Original assignee: Nanjing Niuxin Microelectronics Co ltd
Current assignee: Nanjing Niuxin Microelectronics Co ltd
Priority date: 2019-05-10
Filing date: 2019-05-10
Publication date: 2024-03-26
Anticipated expiration: 2039-05-10
Also published as: CN110086436A

Abstract

The invention discloses a broadband amplifier circuit, which comprises an NMOS high gain amplifier with a common source electrode, and an improved active inductance high-frequency broadband load circuit formed by a cascode NMOS transistor, a switch resistor and a capacitor. The broadband amplifier has the characteristics of high gain, large bandwidth, adjustable bandwidth and low noise, and is particularly suitable for an integrated circuit, and the implementation area is small.

Description

High-frequency broadband amplifier

Technical Field

The present invention relates to a wideband low noise amplifier suitable for a high frequency wideband communication system.

Background

In modern optical fiber communication technologies, communication rates tend to be Gbps, even in excess of 100Gbps, and the need for ultra wideband amplifiers presents a high challenge. In addition, in modern wireless communication, the carrier frequency is also higher and higher, for example, in the 5G wireless communication standard, the carrier frequency is as high as 6GHz, even 28GHz, the channel bandwidth is as high as hundred megabytes, and a high-frequency wideband amplifier is also required. Therefore, for modern communication systems, the requirements and researches on high-frequency broadband amplifiers are more and deeper, and based on the invention, a novel high-frequency broadband low-noise amplifier is provided, and meanwhile, the invention combines the characteristic of small area requirement of an adaptive integrated circuit.

Referring to fig. 1, this is a basic structure diagram of a general amplifier. The resistor R0 and the parasitic capacitance of the drain electrode of the MOS tube N0 form an output load, and the high-frequency gain and the bandwidth of the amplifier are limited due to the low-pass characteristic of RC.

Referring to fig. 2, this is a conventional high frequency wideband amplifier, and the load counteracts the influence of parasitic capacitance by adding peak technology (peak) of inductance, so as to expand the bandwidth, but this approach increases the cost greatly because the area of passive inductance in the integrated circuit is usually larger.

Disclosure of Invention

The invention aims to solve the technical problem of providing a novel high-frequency broadband amplifier with small implementation area and lower noise.

In order to solve the technical problems, the high-frequency broadband amplifier comprises an NMOS high-gain amplifier with a common source electrode, and an improved active inductance high-frequency broadband load circuit formed by a cascode NMOS transistor, a switch resistor and a capacitor.

Drawings

FIG. 1 is a schematic diagram of a generic amplifier architecture;

FIG. 2 is a schematic diagram of a conventional high frequency wideband amplifier;

fig. 3 is a schematic diagram of the basic structure of an active inductor;

FIG. 4 is a small signal equivalent circuit of the active inductor of FIG. 3;

fig. 5 is a detailed circuit diagram of the high frequency broadband amplifier of the present invention.

Fig. 6 is a block diagram of the structure of the high frequency broadband amplifier of the present invention.

The reference numerals in the drawings illustrate:

let x denote natural number, nx be NMOS transistor; px is a PMOS transistor; cx is capacitance; rx is the resistance.

Detailed Description

Referring to fig. 5, the high-frequency wideband amplifier of the present invention is composed of Gm transconductance amplifier and improved active inductive load module. N3 is a common source connection method, provides Gm transconductance, has a gate connected to a signal input, and has a drain connected to the source of N4. N4 is a cascode amplifier, the gate of which is connected to two sets of switching resistors, P0 and R3 are one set controlled by P0 gate control voltage bit <1>, and P1 and R2 are the other set controlled by P1 gate control voltage bit <0 >. A small capacitor C0 is connected across the gate and source of N4. N4 and two groups of switch resistors and capacitors C0 together form an improved active inductance load module.

Referring to fig. 3, N5 is an NMOS active device with a gate connected to a drain through R6, and typically connected to a power source avdd. Referring to fig. 4, gm is the transconductance of N5, cgs is the gate-source capacitance of N5, vgs is the gate-source voltage, rg is the gate resistance (R6 in fig. 3), and the product of Gm and Vgs constitutes the equivalent controlled current source. The impedance of the active inductor can be obtained through the small-signal equivalent model as follows:

Zin = (1+sRgCgs)/(Gm+sCgs)

thereby obtaining the equivalent inductance and the equivalent series resistance as follows:

L = (Rg/wT-1/GmwT)/(1+(w/wT) ² )

R = (1/Gm+Rg(w/wT) ² )/(1+(w/wT) ² )

where wt=gm/Cgs

In the expression of L, when Rg >1/Gm is satisfied, the equivalent circuit model is inductive, meets the use requirement of us, and the size of the equivalent inductance L is generally changed by adjusting Rg and Gm.

The invention further improves the active inductance circuit, referring to fig. 5, the size of the active inductance is flexibly adjusted in the integrated circuit through register setting by adding two groups of switch resistors, and meanwhile, the noise lower than that of the original active inductance model is realized by adding a proper small capacitor C0.

The high-frequency broadband amplifier circuit has the technical characteristics of simple structure, stability, reliability, small implementation area, low noise, high-frequency broadband and the like, and exceeds 6GHz in practical application.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Various modifications and variations of the present invention will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The broadband amplifier circuit is characterized by comprising an NMOS high-gain amplifier with a common source electrode and an active inductance high-frequency broadband load circuit, wherein the active inductance high-frequency broadband load circuit comprises a cascode NMOS transistor, a switch resistor and a capacitor, the grid electrode of the cascode NMOS transistor is connected with the switch resistor, and the capacitor is connected between the grid electrode and the source electrode of the cascode NMOS transistor; the switch resistor at least comprises a PMOS tube and a resistor, wherein the grid electrode of the PMOS tube is controlled by a control signal, the source electrode of the PMOS tube is connected with a power supply, the drain electrode of the PMOS tube is connected with one end of the resistor, and the other end of the resistor is connected with one end of the capacitor; the common-source NMOS high-gain amplifier comprises a common-source NMOS transistor; the grid electrode of the common source NMOS transistor is connected with an input signal, the source electrode of the common source NMOS transistor is grounded, and the drain electrode of the common source NMOS transistor is connected with the source electrode of the cascode NMOS transistor.

2. The broadband amplifier circuit according to claim 1, wherein the number of switching resistors is 2.

3. The broadband amplifier circuit according to claim 1, wherein the number of capacitors is 1.