Distributed amplifier adopting gate-source coupling bandwidth expansion technology

Abstract

The invention belongs to the field of radio frequency integrated circuits, and particularly provides a distributed amplifier adopting a gate-source coupling bandwidth expansion technology, which is used for solving the problem of how to further expand bandwidth on the basis of not losing gain. On the basis of a distributed amplifier structure with an NMOS single tube as a gain unit and a lumped element inductor as a transmission line, a grounding inductor Ls is embedded into a source electrode of the gain unit, the grounding inductor Ls and a grid transmission line inductor are subjected to inverse coupling, input impedance is counteracted through inverse mutual inductance, input matching is further improved, and the gain unit has the advantages that the gain unit is optimized, and the gain unit is optimized. And finally, a distributed amplifier with a higher bandwidth under the same gain is realized.

Description

Technical Field

[0001] The present invention belongs to the field of radio frequency integrated circuits, relates to a distributed amplifier, and specifically provides a distributed amplifier using a gate-source coupling bandwidth extension technology. Background Art

[0002] Millimeter-wave integrated circuits need to provide sufficient available frequency bands for ultra-wideband signals occupying multiple octaves to improve the resolution of integrated systems, high-frequency instruments, and radars; typically, these applications require narrow pulse widths and high data rates, which requires large fractional bandwidths (FBW).

[0003] Distributed amplifiers (DA) have a large FBW in millimeter-wave applications. This structure achieves ultra-wideband by absorbing the device capacitance into the transmission line. Since the high-frequency noise in the entire frequency band is relatively low, distributed amplifiers can play an important role in multi-frequency and multi-mode chips. In an ideal distributed amplifier, that is, the transmission line is lossless and dispersion-free, infinite gain and bandwidth can be achieved. In actual distributed amplifiers, whether using real transmission lines such as coplanar waveguides and microstrip lines, or artificial transmission lines with lumped elements, due to the reflection and loss of the gate and drain transmission lines and other factors, how to break through the bandwidth limitation of distributed amplifiers is still a major problem that needs to be solved. Summary of the invention

[0004] The purpose of the present invention is to provide a distributed amplifier using gate-source coupling bandwidth extension technology to solve the problems existing in the above-mentioned prior art. The technology introduces an inductor at the source of the gain unit transistor. L s and the gate transmission line inductance L g By performing anti-phase coupling, the original bandwidth can be further expanded without losing gain, effectively improving the bandwidth of the distributed amplifier.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A distributed amplifier using gate-source coupling bandwidth extension technology, characterized in that it includes: a gate transmission line inductor, a drain transmission line, a gain unit, a gate terminal resistor, a drain terminal resistor, a signal input terminal, a signal output terminal and a bias network; wherein the gain unit includes a common source transistor M i and source inductance L s ; The gate transmission line consists of N gate inductors L gi and 1 terminal inductor L gtThe drain transmission line consists of a terminal inductor L dt and N Drain inductance L di The gain unit uses a single tube M i , a source inductor is connected between the source and ground of each gain unit L si ,in, N is the number of gain units, which can be selected from positive integers greater than 1, i is 1 to N The i-th gate inductor is connected to the i+1-th gate inductor and the input end of the i-th gain unit; the i-1-th drain inductor is connected to the i-th drain inductor and the output end of the i-th gain unit; the gate terminal inductor and the drain terminal inductor are connected to the terminal resistance of their respective transmission lines respectively; the i-th source inductor is coupled to the i-th gate inductor, and the coupling coefficient is k .

[0007] Furthermore, the gain unit uses NMOS transistors with the same structure size, and the gate-source inductive coupling parameters need to satisfy the following relationship:

[0008]

[0009]

[0010] in, k is the gate-source inductance coupling coefficient, and a value less than 0 indicates reverse coupling of the transformer.

[0011] The beneficial effects of the present invention are:

[0012] The present invention provides a distributed amplifier using a gate-source coupling bandwidth extension technology, wherein a gain unit source inductance and a gate transmission line inductance form a series-series feedback, which is equivalent to introducing an adjustable passive inductance and resistance into the gate loading transmission line, thereby affecting the real part and the imaginary part of the overall input impedance; on the basis of substantially not losing DC gain, the effects of bandwidth extension and input matching improvement are achieved, and the circuit bandwidth is effectively extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the overall circuit of the distributed amplifier using the gate-source coupling bandwidth extension technology in the present invention.

[0014] Figure 2 An equivalent model of a transmission line loaded with an input of a conventional distributed amplifier without adding a source inductor in the present invention is shown.

[0015] Figure 3The invention provides an equivalent model of the input loading transmission line of the distributed amplifier using the gate-source inductive coupling technology.

[0016] Figure 4 1 is a gain response simulation result of a distributed amplifier using gate-source coupling bandwidth extension technology in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and technical effect of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0018] This embodiment provides a distributed amplifier structure that couples the gate transmission line inductance with the gain unit source inductance. Figure 1 As shown, it includes: a gain unit, a gate transmission line, a drain transmission line, a gate terminal resistor, a drain terminal resistor, a signal input terminal and a signal output terminal;

[0019] A distributed amplifier using gate-source coupling bandwidth extension technology, characterized in that it includes: a gate transmission line inductor, a drain transmission line, a gain unit, a gate terminal resistor, a drain terminal resistor, a signal input terminal, a signal output terminal and a bias network; wherein the gain unit includes a common source transistor M i and source inductance L s ; The gate transmission line consists of N gate inductors L gi and 1 terminal inductor L gt The drain transmission line consists of a terminal inductor L dt and N Drain inductance L di The gain unit uses a single tube M i , a source inductor is connected between the source and ground of each gain unit L si ,in, N is the number of gain units, which can be selected from positive integers greater than 1, i is 1 to N The i-th gate inductor is connected to the i+1-th gate inductor and the input end of the i-th gain unit; the i-1-th drain inductor is connected to the i-th drain inductor and the output end of the i-th gain unit; the gate terminal inductor and the drain terminal inductor are connected to the terminal resistance of their respective transmission lines respectively; the i-th source inductor is coupled to the i-th gate inductor, and the coupling coefficient is k .

[0020] The circuit structure signal flow inputs the signal from the input portV in , starts to propagate to the right, and after some delay reaches the gate of the gain unit. Once the gate receives the input signal, the transistor absorbs a current equal to the current from the drain transmission line. g m V in The current to the left and right of this current sees the terminal impedance value, which is divided into g m V in R / 2 voltage signal is transmitted to the left and right respectively; in order to ensure that the time when each gain unit receives the input signal is exactly equal to the time when the output signal generated by the previous gain unit reaches its drain, it is necessary to ensure that the wave speed of the drain transmission line and the gate transmission line are equal; the signals reaching the terminals of the gate transmission line and the drain transmission line are absorbed by the terminal resistors.

[0021] Furthermore, the gain unit uses NMOS transistors of the same size, and sets the source inductance value to be equal to the gate inductance value, takes N gate inductors and coupling coefficients to be equal, and in order to ensure maximum bandwidth expansion, the coupling coefficient needs to be as large as possible.

[0022] In terms of working principle: in the present invention, a source inductor is embedded between the source and ground of the gain unit, and it is anti-coupled with the gate transmission line inductor to form a series-series feedback, so that the input impedance of the overall circuit changes; more specifically: the equivalent model of the input loaded transmission line of the traditional structure (without adding source inductor) is as follows Figure 2 As shown, using the ladder network analysis method, the input impedance of the input-loaded transmission line of the traditional structure is:

[0023]

[0024] Where ω is the angular frequency, L g and C gg are the inductance of the gate transmission line and the total parasitic capacitance of the gate of the gain unit, respectively.

[0025] The present invention proposes a distributed amplifier structure that introduces a source inductor at the source of a gain unit and couples it inversely with the gate transmission line inductor. The equivalent model of the input loading transmission line is as follows: Figure 3 As shown, its input impedance is:

[0026]

[0027] in, L s is the source inductance, Mis the mutual inductance of the source inductance and the gate transmission line inductance, ω T is the characteristic frequency of the transistor; it can be seen that reactance cancellation and impedance matching can be achieved by adjusting the coupling coefficient and the source inductance value, thereby achieving bandwidth expansion.

[0028] In this embodiment, all gain units use NMOS transistors with a width-to-length ratio of 8um / 40nm, the gate transmission line inductance value and the drain transmission line inductance value are set to 26pH, the source inductance value is set to 26pH, the power supply voltage is 1.2V, the bias current is 3.47mA, and the input and output port impedances and terminal load resistances are both 50Ω; in order to demonstrate the bandwidth extension effect obtained by the present invention, the gain response results of the present invention and the traditional structure are compared.

[0029] Finally, this embodiment achieves bandwidth expansion. As its low-frequency gain is basically maintained at around 8dB, the -3dB bandwidth is increased from 84GHz to 140GHz, achieving a 67% expansion effect. Figure 4 shown.

[0030] The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other alternative features that are equivalent or have similar purposes; all the disclosed features, or all the steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A distributed amplifier using gate-source coupling bandwidth extension technology, characterized in that: include: A gate transmission line inductor, a drain transmission line, a gain unit, a gate terminal resistor, a drain terminal resistor, a signal input terminal, a signal output terminal and a bias network; wherein the gain unit includes a common source transistor M i and source inductance L s ; The gate transmission line consists of N gate inductors L gi and 1 terminal inductor L gt The drain transmission line consists of a terminal inductor L dt and N Drain inductance L di The gain unit uses a single tube M i , a source inductor is connected between the source and ground of each gain unit L si ,in, N is the number of gain units, which can be selected from positive integers greater than 1, i is 1 to N The i-th gate inductor is connected to the i+1-th gate inductor and the input end of the i-th gain unit; the i-1-th drain inductor is connected to the i-th drain inductor and the output end of the i-th gain unit; the gate terminal inductor and the drain terminal inductor are connected to the terminal resistance of their respective transmission lines respectively; the i-th source inductor is coupled to the i-th gate inductor, and the coupling coefficient is k .

2. The distributed amplifier using gate-source coupling bandwidth extension technology according to claim 1, characterized in that: The gain cell source inductance L s and gate transmission line inductance L g satisfy: L s = L g .

3. The distributed amplifier using gate-source coupling bandwidth extension technology according to claim 1, characterized in that: The gain cell source inductance L s and gate transmission line inductance L g It is necessary to satisfy the reverse coupling and the coupling coefficient: k <0.

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