Digitizing switching circuit based on a current mirror

Abstract

The application discloses a digital switch circuit based on a current mirror, which is applied to the field of communication and aims at the existing amplifier switch switching scheme, which needs an additional bias circuit to provide a bias voltage for the amplifier, and when process and temperature deviations occur, the bias voltage often deviates, which causes the amplifier to deviate from a static working point and deteriorates the circuit performance; the application combines the current mirror and the transistor switch, effectively turns off the amplifier not in the working state when the transmitting and receiving channels are switched, and provides a gate bias voltage for the amplifier according to the static working point of the amplifier. When process and temperature deviations occur, the size of the drain current of the amplifier is adjusted by adjusting the path of the switch, and then the gain of the amplifier is controlled, which greatly improves the interference resistance of the amplifier.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of communication, in particular relates to an amplifier switch switching circuit. BACKGROUND

[0002] With the wide application of phased array system technology in the field of wireless communication, the demand for high-precision, high-integration, fast response and multi-functional transceiver front end of communication system is increasingly urgent. The transceiver front end is a key component module of the phased array system, which undertakes the functions of transceiver switching, amplitude and phase adjustment of radio frequency signals. A typical phased array system needs multiple transceiver front ends to work cooperatively to realize its functions. The multi-functional transceiver front end chip often needs to switch the transceiver channel, and the amplifiers of the transceiver channel do not work at the same time. The amplifier consumes the most direct current power, so closing the amplifier that is not in working state can effectively reduce the power consumption of the whole chip, and also increase the isolation of the transceiver channel. To realize such a function, a switch switching circuit needs to be added to the amplifier.

[0003] The commonly used switch scheme at present is mainly to add a switch tube between the gate of the amplifier transistor and the bias voltage. The switch makes the gate switch between the normal supply voltage and ground, so as to achieve the effect of controlling the working state of the amplifier. Although this kind of way can realize the simple switching of the working state of the amplifier, it still needs an additional bias circuit to provide bias voltage for the amplifier. For the cascode structure, only the common source or the common gate stage is turned off, or both of them are turned off. In these three cases, the source-drain voltage of the upper and lower transistors may not be evenly divided from the drain supply voltage, that is, it will exceed the static working point of the transistor in the on state of the amplifier. At the same time, due to the process deviation and the change of the working temperature of the chip in later period, the bias voltage will often deviate, causing the amplifier to deviate from the static working point, thus causing the deterioration of the circuit performance. SUMMARY

[0004] To solve the above technical problems, the present application provides a digital switch circuit based on current mirror, which can realize the switching of the multi-functional chip amplifier in the transceiver state, control the gate bias voltage of the amplifier, and adjust the performance of the amplifier when the process and temperature change.

[0005] The technical scheme adopted by the present application is: a digital switch circuit based on current mirror, comprising: transistors M1, M2, M3, M4, M5, M6, M7, M8, M9 and M10.

[0006] The gate of transistor M1 is connected to the gate of transistor M6, the drain of transistor M1 is connected to the drain of transistor M2, and the drain of transistor M1 is also connected to the drain of transistor M6. The source of transistor M6 is grounded. The gate of transistor M2 is connected to the drain of transistor M2, the gate of transistor M2 is connected to the gate of transistor M3, the drain of transistor M3 is connected to the drain of transistor M9, the gate of transistor M4 is connected to the gate of transistor M2, the drain of transistor M4 is connected to the source of transistor M7, the drain of transistor M7 is connected to the drain of transistor M9, the gate of transistor M5 is connected to the gate of transistor M2, the drain of transistor M5 is connected to the source of transistor M8, and the drain of transistor M8 is connected to the drain of transistor M9. The sources of transistors M1, M2, M3, M4, and M5 are all connected to VDD.

[0007] The gates of transistors M7 and M8 are respectively connected to their respective control voltages;

[0008] The drain of transistor M9 is connected to the gate, the source of transistor M9 is connected to the source of transistor M10, the drain of transistor M10 is connected to the gate of transistor M9, the first terminal of the capacitor is connected to the gate of transistor M9, and the second terminal of the capacitor is grounded; the control voltage connected to the gate of transistor M10 is the voltage obtained by the inverter after the control voltage connected to the gate of transistor M1.

[0009] The voltage output from the gate of transistor M9 is used as the bias voltage for the amplifier circuit.

[0010] The beneficial effects of this invention are as follows: This invention provides a novel amplifier switching circuit design. This design combines a current mirror and a transistor switch, enabling effective shutdown of the amplifier when it is not in operation during transmit / receive channel switching. Simultaneously, it provides a gate bias voltage to the amplifier based on its quiescent operating point. Furthermore, to address deviations in process technology and temperature, the amplifier's drain current is adjusted by modifying the switch path, thereby controlling the amplifier gain and significantly improving the amplifier's immunity to interference. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a digital switching circuit based on a current mirror.

[0012] Figure 2 This is the circuit schematic of the single-stage distributed amplifier that needs to be controlled in this invention.

[0013] Figure 3 This is the circuit design layout of the present invention.

[0014] Where 1 is the control voltage V CTR1 2 represents the power supply voltage VDD, and 3 represents the control voltage V. CTR2 4 represents the control voltage VCTR3 5 is an output bias voltage V BIAS_OUT 6 is ground. DETAILED DESCRIPTION

[0015] For the skilled in the art to understand the technical content of the present application, the content of the present application is further explained below in combination with the drawings.

[0016] As shown in Figure 1 , V CTR1 is the control voltage of the whole switch, M1 and M10 are circuit switch tubes, M6 works in the linear region, equivalent to a resistor, providing a reference current I DM6 . M2 and M3, M4 and M5 respectively constitute current mirrors, so that the reference current generated by M6 is respectively copied to the right branch in a certain proportion. In general circuit design, three current branches are generally used, and the number of current branches can be appropriately increased according to the actual situation. M7 and M8 are used as switches to control the on-off of the latter two current branches, V CTR2 and V CTR3 are control voltages for controlling the on-off of M7 and M8, and under normal circumstances, only one branch needs to be turned on, at which time I ref = I A + I B When the temperature rises, thermal excitation will cause more electrons to transition from the valence band to the conduction band, thereby increasing the free carriers, so that the carrier concentration of each transistor will increase, resulting in an increase in drain current. Therefore, as shown in Figure 1 , the drain current I ref of transistor M9 will be greater than the current in the normal working state, and by turning off the I B current branch, I ref = I A at this time, the drain current of transistor M9 is adjusted; similarly, when the ambient temperature decreases, the drain current of the transistor decreases at this time, and the drain current I ref of transistor M9 will be less than the current in the normal working state, and by turning on another I B current branch, I ref = I A + 2I B at this time; by reasonably designing the current size of the I B current branch, the current size is made to be equal to the increase or decrease of I ref at high and low temperatures as much as possible, so that when the process or temperature changes, the present application only needs to adjust the on-off of the I B current branch, so that I ref can always remain at a relatively stable size.

[0017] The working principle of the switch circuit to realize the switching function is: when V CTR1When V CTR4 is high, V BIAS_OUT is inverted by the inverter, and V CTR1 is low, M1 and M10 are both off, and the core circuit works normally to output the bias voltage V CTR4 and the bias current. When V BIAS_OUT is high, M1 and M10 are both on, and M1 and M10 can be regarded as a wire, so that M2 and M9 are short-circuited, and the bias voltage V BIAS_OUT and the bias current are both 0, and the gate of M11 is biased to the ground, so that the amplifier circuit is turned off.

[0018] M9 is diode-connected, and M11 in the amplifier circuit shown in FIG. 1 forms a current mirror, so that the reference current Iref is copied into the amplifier in proportion. Figure 2 According to the static working point of the amplifier transistor M11, the output voltage of the switch circuit is adjusted by adjusting the width-length ratio of M9, so that the gate bias voltage of M11 is provided.

[0019] First, according to the static working point of the amplifier transistor, the gate bias voltage of M11 and the drain working current of the branch are determined. In this embodiment, the drain working current of the amplifier branch is 14.5 mA, the gate bias voltage of M11 is 0.62 V, the width-length ratio of M11 is 5uM / 60nM, and the Finger number is 30. The related design of the amplifier will not be expanded here. That is, Figure 1 The output voltage V BIAS_OUT of the switch switching circuit shown in FIG. 2 is 0.62 V. Considering the power consumption of the switch circuit, the W / L of M9 is 5uM / 60nM, and the Finger number is 7, so the reference current I ref is about 2.1 mA. In the normal working state, only two branches are on, that is, I ref =I A +I B , usually I A =2I B , so I A =1.4 mA and I B =0.7 mA. According to the design, the width-length ratio of M6 is 1uM / 400nM, the width-length ratio of M2 is 4uM / 400nM, and the Finger number is 10, so I DM6= 0.7 mA. According to the current mirror principle, the width-length ratio of M3 is 4 uM / 400 nM, the Finger number is 20, the width-length ratio of M4 and M5 is 4 uM / 400 nM, and the Finger number is 10. At this time, the output bias current Iref is 2.1 mA, and the output bias voltage is 0.62 V. Considering the layout design and matching, for the switch tube Ml, the width-length ratio is 4 uM / 400 nM, and the Finger number is 5; for the switch tubes M7 and M8, the width-length ratio is 4 uM / 400 nM, and the Finger number is 10; for the switch tube M10, the width-length ratio is 1 uM / 400 nM, and the Finger number is 3; and the decoupling capacitor C is 1 pF.

[0020] Figure 3 For the layout of the embodiment, in order to achieve good layout matching and reduce errors caused by manufacturing processes, when designing the layout of the transistors constituting the current mirror circuit, the transistor Finger number is taken as a basic unit of 5, and the transistor Multiplier number is changed to realize current replication. The layout area size is about 70 μm*30 μm, and the layout occupies a small area, so it is easy to embed it into the final layout design for a general amplifier circuit.

[0021] Those skilled in the art will appreciate that the embodiments described herein are presented for the purpose of helping the reader to understand the principles of the present application, and should be understood as not limiting the scope of protection of the present application to such specific statements and embodiments. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the scope of protection of the claims of the present application.

Claims

1. A digital switching circuit based on a current mirror, characterized in that, include: Transistor M1, transistor M2, transistor M3, transistor M4, transistor M5, transistor M6, transistor M7, transistor M8, transistor M9, transistor M10; The gate of transistor M1 is connected to the gate of transistor M6, the drain of transistor M1 is connected to the drain of transistor M2, and the drain of transistor M1 is also connected to the drain of transistor M6. The source of transistor M6 is grounded. The gate of transistor M2 is connected to the drain of transistor M2, the gate of transistor M2 is connected to the gate of transistor M3, the drain of transistor M3 is connected to the drain of transistor M9, the gate of transistor M4 is connected to the gate of transistor M2, the drain of transistor M4 is connected to the source of transistor M7, the drain of transistor M7 is connected to the drain of transistor M9, the gate of transistor M5 is connected to the gate of transistor M2, the drain of transistor M5 is connected to the source of transistor M8, and the drain of transistor M8 is connected to the drain of transistor M9. The sources of transistors M1, M2, M3, M4, and M5 are all connected to VDD. The gates of transistors M7 and M8 are respectively connected to their respective control voltages; The drain of transistor M9 is connected to the gate, the source of transistor M9 is grounded to the source of transistor M10, the drain of transistor M10 is connected to the gate of transistor M9, the first terminal of capacitor is connected to the gate of transistor M9, and the second terminal of capacitor is grounded. The control voltage connected to the gate of transistor M10 is the voltage obtained after the control voltage connected to the gate of transistor M1 is inverted. The voltage output from the gate of transistor M9 is used as the bias voltage for the amplifier circuit.

2. The digital switching circuit based on a current mirror according to claim 1, characterized in that, The aspect ratio and finger number of transistors M4 and M5 are designed to meet the following requirements: When transistors M7 and M8 are turned on, the source output currents of transistors M4 and M5 are equal, and the magnitude of the current is equal to the increase or decrease of the reference current Iref flowing into the source of transistor M9 when the temperature changes.

3. The digital switching circuit based on a current mirror according to claim 2, characterized in that, When the temperature changes, the reference current Iref flowing into the drain of transistor M9 is kept stable by controlling the conduction state of transistors M7 and M8.

4. The digital switching circuit based on a current mirror according to claim 3, characterized in that, The amplifier is implemented using CMOS transistors. Specifically, the parasitic capacitance at the input terminal of the CMOS transistor is connected in series with the on-chip inductor at the input terminal to form the gate input artificial transmission line; the parasitic capacitance at the output terminal of the CMOS transistor is connected in series with the on-chip inductor at the output terminal to form the drain output artificial transmission line. The gate input artificial transmission line and the drain output artificial transmission line are coupled through the transconductance of the CMOS transistor to amplify the input signal; Transistor M9 and the CMOS transistor in the amplifier form a current mirror.

5. The digital switching circuit based on a current mirror according to claim 4, characterized in that, The bias voltage of the amplifier circuit is adjusted by adjusting the width-to-length ratio of the M9 transistor based on the quiescent operating point of the CMOS transistor in the amplifier.

6. The digital switching circuit based on a current mirror according to claim 5, characterized in that, The number of fingers for each transistor is based on a unit of 5.

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