CN105305979B

CN105305979B - A kind of distributed amplifier circuit for improving the linearity

Info

Publication number: CN105305979B
Application number: CN201510737532.8A
Authority: CN
Inventors: 张瑛
Original assignee: Nanjing Post and Telecommunication University
Current assignee: Nanjing Post and Telecommunication University
Priority date: 2015-11-03
Filing date: 2015-11-03
Publication date: 2018-03-06
Anticipated expiration: 2035-11-03
Also published as: CN105305979A

Abstract

The invention discloses a kind of distributed amplifier circuit for improving the linearity, including several gain units and it is connected to the input on-chip inductor of each gain unit input, is connected to the output on-chip inductor of each gain unit output end, interstage matched electric capacity is provided with before or after at least one input on-chip inductor, the input of each gain unit is connected with biasing resistor, applies bias voltage from the other end of the biasing resistor.Gain unit of the invention by using different circuit structures, and apply different bias voltage and can change the quiescent point of each gain unit, so as to improve their linearity, the direct current biasing of each gain unit input is kept apart in the introducing of interstage matched electric capacity, so as to apply different bias voltages to the input of each gain unit, so as to add the free degree of design and debugging.

Description

A kind of distributed amplifier circuit for improving the linearity

Technical field

The invention belongs to technical field of integrated circuits, more particularly to a kind of distributed amplifier circuit for improving the linearity.

Background technology

The rapid development of wireless communication technology proposes requirements at the higher level to the data transmission rate and bandwidth of communication system.Generally The broad band amplifier designing technique of use includes negative-feedback, balance amplifier, resistors match and active matching etc., but this A little technologies can not effective boost amplifier gain bandwidth product.Distributed amplifier can be dashed forward due to the characteristic in its structure The limitation of broken amplifier gain bandwidth product, more wide band signal amplification is realized, super including microwave power amplifier Obtained in broadband MMIC (Monolithic Microwave Integrated Circuit, monolithic integrated microwave circuit) field It is widely applied.Has there is various types of structures, including heterogeneous texture, distribution-cascade in current distributed amplifier Structure etc., but they are all artificial transmission line's forms using lowpass structures, and now all gain units all must operate at Under same bias state, therefore design freedom is relatively low, can not improve distributed air-defense by setting different operating points The performances such as the linearity of device.

The general principle of distributed amplifier is that the parasitic capacitance of transistor and inductance element are formed into artificial transmission line, from And overcoming roll off of gain caused by parasitic capacitance, its circuit theory diagrams is as shown in figure 1, wherein VDD is supply voltage, V_GFor direct current Bias voltage, on-chip inductor L_GiInput impedance with gain unit constitutes input artificial transmission line, on-chip inductor L_DiAnd gain The output impedance of unit constitutes output artificial transmission line, it is clear that input/output artificial transmission line is low-pass filter structure. Traditional distributed amplifier is because gain per stage unit uses direct coupling system, therefore each gain unit must operate at Under the conditions of same direct current biasing.

The content of the invention

In view of above-mentioned deficiency of the prior art, the present invention proposes a kind of distributed amplifier circuit for improving the linearity, Its technical scheme is：

It is a kind of to improve the distributed amplifier circuit of the linearity, including several gain units and it is connected to each increasing The input on-chip inductor of beneficial unit input, the output on-chip inductor for being connected to each gain unit output end, at least Interstage matched electric capacity is provided with before or after one input on-chip inductor, the input of each gain unit is connected with partially Resistance is put, applies bias voltage from the other end of the biasing resistor.

Preferably, it is provided with interstage matched electric capacity before each input on-chip inductor.

Before first output on-chip inductor and last output on-chip inductor is in series with a coupling respectively Electric capacity.

The gain unit is a NMOS tube, and its grid is input, is drained as output end.

The gain unit is made up of the NMOS tube of two connections, the drain electrode of the source electrode of the first NMOS tube and the second NMOS tube Connection, the grid of the second NMOS tube is input, and the drain electrode of the first NMOS tube is output end.

The gain unit is made up of two NMOS tubes and an inductance, the source electrode of the first NMOS tube and described inductance one end Connection, the other end of the inductance connect the drain electrode of the second NMOS tube, and the grid of the second NMOS tube is input, the first NMOS tube Drain electrode be output end.

The present invention and applies different bias voltage and can changed respectively by using the gain unit of different circuit structures The quiescent point of individual gain unit, so as to improve their linearity, the introducing of interstage matched electric capacity is by each gain list The direct current biasing of first input is kept apart, so as to apply different bias voltages to the input of each gain unit, from And add the free degree of design and debugging.

Brief description of the drawings

Fig. 1 is traditional distributed amplifier circuit structure diagram；

Fig. 2 is distributed amplifier circuit structure diagram of the embodiment of the present invention；

Fig. 3 is one embodiment structure chart of gain unit in Fig. 2；

Fig. 4 is another example structure figure of gain unit in Fig. 2；

Fig. 5 is another example structure figure of gain unit in Fig. 2；

Fig. 6 is output current, transadmittance gain and the all-order derivative of Fig. 3 embodiments and the relation of input voltage；

Fig. 7 is output current, transadmittance gain and the all-order derivative of Fig. 4 and Fig. 5 embodiments and the relation of input voltage.

Embodiment

In order to make the purpose , technical scheme and advantage of the present invention be clearer, it is right below in conjunction with drawings and Examples The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and It is not used in the restriction present invention.

Distributed amplifier circuit structure of the present invention as shown in Fig. 2 compared with the traditional distributed amplifier shown in Fig. 1, Exist and improved at following three：

(1) interstage matched electric capacity is provided with before or after at least one input on-chip inductor, with L_GiCollectively form band logical Matching network, in each input on-chip inductor L in Fig. 2_GiBefore be connected with electric capacity C_Gi, actually C_GiAlso L can be placed on_GiAfterwards；C_Gi's Quantity is [1, N]；

(2) independent bias structure R is employed in the input of the gain unit provided with interstage matched electric capacity_Gi, can with this To apply different bias voltage V to the input of gain unit_Gi；

(3) gain unit can use any circuit structure as shown in Fig. 3 to Fig. 5, but general in same circuit Use identical circuit structure.

The principle of distributed amplifier circuit of the present invention is as follows：

The output current i of gain unit_oWith input offset voltage v_inBetween be constantly present following relational expression

Wherein g_mRepresent the transadmittance gain of gain unit, g '_mFor i_oOn v_inSecond dervative, g "_mFor i_oOn v_inThree Order derivative.

Theoretical, the g " according to radio circuit_mIt is maximum to the linearity performance impact of amplifier, g_mIn the case of certain, g "_mMore The linearity of small then amplifier is better.Relation between the transconductance characteristic and input offset voltage of the gain unit of different structure is such as Shown in Fig. 6 and Fig. 7.

As shown in figure 3, a kind of structure of gain unit is a NMOS tube, its grid is input, drains as output end, adopts With distributed amplifier circuit output current, transadmittance gain and the all-order derivative of this structure and relation such as Fig. 6 of input voltage It is shown.By Fig. 6 (b) it can be seen that gain unit shows serious non-linear, i.e. transadmittance gain g_mIt is not constant value, but With input offset voltage v_inChange and change, therefore when amplifier input signal amplitude increase when, output signal will go out Existing non-linear distortion.

As shown in figure 4, another structure of gain unit is：Gain unit is made up of the NMOS tube of two connections, and first The source electrode of NMOS tube is connected with the drain electrode of the second NMOS tube, and the grid of the second NMOS tube is input, the drain electrode of the first NMOS tube For output end.

As shown in figure 5, another structure of gain unit is：Gain unit is made up of two NMOS tubes and an inductance, The source electrode of first NMOS tube is connected with inductance one end, and the other end of inductance connects the drain electrode of the second NMOS tube, the second NMOS tube Grid is input, and the drain electrode of the first NMOS tube is output end, and the inductance is peak value inductance.Using two kinds of structures of Fig. 4 and Fig. 5 The relation of distributed amplifier circuit output current, transadmittance gain and all-order derivative and input voltage is as shown in Figure 7.By Fig. 7 (a) (b) it can also be seen that gain unit shows serious non-linear, i.e. transadmittance gain g_mIt is not constant value, but with defeated Enter bias voltage v_inChange and change, therefore when amplifier input signal amplitude increase when, output signal will appear from non-thread Property distortion.

According to the operation principle of distributed amplifier, its forward direction transadmittance gain is the folded of each gain unit transadmittance gain Add, therefore when each gain unit using the circuit structure of identical (or different) and is in it can be seen from Fig. 6 (d) and Fig. 7 (d) During different input offset voltage, g "_mIt can take on the occasion of negative value can also be taken, therefore only need by adjusting each gain unit Bias voltage can make it that the second order local derviation of total transadmittance gain of distributed amplifier levels off to zero, it is good so as to obtain The linearity.

Technological means disclosed in the present invention program is not limited only to the technological means disclosed in above-mentioned embodiment, in addition to Formed technical scheme is combined by above technical characteristic.

Claims

Improve the distributed amplifier circuit of the linearity 1. a kind of, including several gain units and be connected to each gain The input on-chip inductor of unit input, the output on-chip inductor for being connected to each gain unit output end, its feature exist In：It is each it is described input on-chip inductor before be provided with interstage matched electric capacity, first it is described output on-chip inductor before with A coupled capacitor is in series with respectively after last output on-chip inductor；The input of each gain unit is connected with partially Resistance is put, applies bias voltage from the other end of the biasing resistor.
2. distributed amplifier circuit according to claim 1, it is characterised in that：The gain unit is a NMOS tube, Its grid is input, is drained as output end.
3. distributed amplifier circuit according to claim 1, it is characterised in that：What the gain unit was connected by two NMOS tube is formed, and the source electrode of the first NMOS tube is connected with the drain electrode of the second NMOS tube, and the grid of the second NMOS tube is input, the The drain electrode of one NMOS tube is output end.
4. distributed amplifier circuit according to claim 1, it is characterised in that：The gain unit is by two NMOS tubes Formed with an inductance, the source electrode of the first NMOS tube is connected with described inductance one end, the other end connection second of the inductance The drain electrode of NMOS tube, the grid of the second NMOS tube is input, and the drain electrode of the first NMOS tube is output end.