Digital switching circuit based on current mirror

Abstract

The invention discloses a digital switching circuit based on a current mirror, which is applied to the field of communication, and aims to solve the problems that an existing amplifier switching scheme needs an additional bias circuit to provide bias voltage for an amplifier, and when process and temperature deviations occur, the bias voltage tends to generate deviation, so that the amplifier deviates from a quiescent operating point, and the power consumption is low. And the circuit performance is deteriorated. According to the invention, the current mirror and the transistor switch are combined, so that the amplifier which is not in a working state is effectively turned off when the receiving and transmitting channels are switched, and meanwhile, the grid bias voltage is provided for the amplifier according to the quiescent working point of the amplifier. When deviation of process, temperature and the like occurs, the size of the drain current of the amplifier is adjusted by adjusting the access of the switch, so that the gain of the amplifier is controlled, and the interference resistance of the amplifier is greatly improved.

Description

Technical Field

[0001] The invention belongs to the field of communications, and in particular relates to an amplifier switch switching circuit. Background Art

[0002] With the widespread application of phased array system technology in the field of wireless communications, the communication system has an increasingly urgent need for high-precision, high-integration, and fast-response multifunctional transceiver front-ends. The transceiver front end is a key component of the phased array system, which is responsible for the transceiver switching, amplitude and phase adjustment of the RF signal. A typical phased array system requires multiple transceiver front ends to work together according to rules to achieve its functions. Multifunctional transceiver front-end chips often need to switch transceiver channels, but the amplifiers of the transceiver channels do not work at the same time, and the amplifiers consume the most DC power. Turning off the amplifiers that are not in operation can effectively reduce the power consumption of the entire chip, while also increasing the isolation of the transceiver channels. To achieve this function, it is necessary to add a switch switching circuit to the amplifier.

[0003] The commonly used switching scheme at present is mainly to add a switch tube between the gate and the bias voltage of the amplifier transistor. The switch switches the gate between the normal power supply voltage and the ground, thereby achieving the effect of controlling the working state of the amplifier. Although this method can realize the simple switching of the amplifier switch state, it also requires an additional bias circuit to provide a bias voltage for the amplifier. For the Cascode structure, only the common source or the common gate level is turned off, or both are turned off at the same time. In these three cases, the source-drain voltage of the upper and lower transistors may not evenly divide the drain supply voltage, that is, it will exceed the static operating point of the transistor when the amplifier is turned on. At the same time, due to the deviation of the processing technology and the change of the chip operating temperature in the later stage, its bias voltage often deviates, causing the amplifier to deviate from the static operating point, thereby causing the circuit performance to deteriorate. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a digital switching circuit based on a current mirror, which can realize the switching of the multi-functional chip amplifier in the transmitting and receiving state, realize the control of the amplifier gate bias voltage, and at the same time, can adjust the performance of the amplifier when the process and temperature change.

[0005] The technical solution adopted by the present invention is: a digital switch circuit based on a current mirror, comprising: a transistor M1, a transistor M2, a transistor M3, a transistor M4, a transistor M5, a transistor M6, a transistor M7, a transistor M8, a transistor M9, and a transistor 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, the drain of transistor M1 is also connected to the drain of transistor M6, and 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 source of transistor M1, the source of transistor M2, the source of transistor M3, the source of transistor M4, and the source of transistor M5 are all connected to VDD;

[0007] The gate of the transistor M7 and the gate of the transistor M8 are connected to respective control voltages respectively;

[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 end of the capacitor is connected to the gate of transistor M9, and the second end of the capacitor is grounded; the control voltage connected to the gate of transistor M10 is the voltage of the control voltage connected to the gate of transistor M1 after passing through an inverter;

[0009] The voltage outputted from the gate of transistor M9 serves as the bias voltage of the amplifier circuit.

[0010] Beneficial effects of the invention: The invention provides a novel amplifier switch switching circuit design scheme. The scheme combines a current mirror with a transistor switch to effectively shut down the amplifier that is not in a working state when the transceiver channel is switched, and at the same time, provide a gate bias voltage for the amplifier according to the static operating point of the amplifier. When deviations such as process and temperature occur, the size of the amplifier drain current is adjusted by adjusting the switch path, thereby controlling the amplifier gain, which greatly improves the amplifier's ability to resist interference. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0012] Figure 2 It is a schematic diagram of a single-stage distributed amplifier circuit that needs to be controlled by the present invention.

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

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

[0015] To facilitate those skilled in the art to understand the technical content of the present invention, the present invention is further explained below with reference to the accompanying drawings.

[0016] like Figure 1 As shown, V CTR1 It is the control voltage of the entire switch. M1 and M10 are circuit switch tubes. M6 works in the linear region, which is equivalent to a resistor and provides a reference current I DM6 M2, M3, M4 and M5 form current mirrors respectively, so that the reference current generated by M6 is copied to the right branch according to a certain ratio. In general circuit design, three current branches are generally used. According to the actual situation, more current branches can be added appropriately. M7 and M8 are used as switches to control the on and off of the two current branches behind. V CTR2 With V CTR3 are the control voltages for controlling the on and off of M7 and M8 respectively. Under normal circumstances, only one branch needs to be turned on. At this time, I ref =I A +I B When the temperature rises, thermal excitation will cause more electrons to jump from the valence band to the conduction band, thereby increasing the number of free carriers, which will increase the carrier concentration of each transistor and lead to an increase in the drain current. Figure 1 The drain current I at the transistor M9 is shown ref will be greater than the current in its normal working state. By turning off I B The current branch makes I ref =I A , to adjust the drain current of transistor M9; similarly, when the ambient temperature decreases, the drain current of the transistor decreases, and the drain current of transistor M9 I ref will be smaller than the current in normal working state, by conducting another I B The current branch makes I ref =I A +2I B ; Through I B Reasonable design of the current branch current size makes its current size as equal as possible to the high and low temperature change I ref The increase or decrease of the amount, so when the process or temperature conditions change, the present invention only needs to adjust I B The on and off of the current branch can make I ref Always maintain a relatively stable size.

[0017] The working principle of the switching circuit to achieve the switching function is: when V CTR1When it is high potential, after the inverter, V CTR4 is low potential. In this case, both M1 and M10 are turned off. At this time, the core circuit works normally and the output bias voltage V BIAS_OUT With the bias current, taking a single-stage distributed amplifier as an example, at this time, the gate of M11 is biased to the normal static operating point, and the circuit works normally. CTR1 When it is low potential, V CTR4 is high potential, M1 and M10 are both turned on, and M1 and M10 can be regarded as a wire, so that M2 and M9 are short-circuited, and the circuit outputs a bias voltage V BIAS_OUT The bias current is 0, and the gate of M11 is biased to ground, thus turning off the amplifier circuit.

[0018] M9 is a diode connection. Figure 2 The transistor M11 in the amplifier circuit shown forms a current mirror, thereby copying the reference current Iref to the amplifier in proportion. According to the static operating point of the amplifier common source transistor M11, by adjusting the width-to-length ratio of the M9 transistor, the output voltage of the switch circuit can be adjusted to provide an ideal gate bias voltage for the transistor M11.

[0019] First, according to the static operating point of the amplifier transistor, the gate bias voltage of the M11 tube and the drain operating current of the branch are determined. In this embodiment, the drain operating current of the amplifier branch is 14.5mA, the M11 gate bias voltage is 0.62V, the width-to-length ratio of the M11 tube is 5uM / 60nM, and the finger number is 30. The relevant design of the amplifier will not be elaborated here. Figure 1 The switching circuit shown in the figure outputs a voltage V BIAS_OUT is 0.62V. Considering the power consumption of the switching circuit, the W / L of the M9 tube is 5uM / 60nM, and the number of fingers is 7, then the reference current I ref It is about 2.1mA. Under normal working conditions, only two branches are conducting, namely I ref =I A +I B , usually let I A =2I B , then at this time I A =1.4mA, I B =0.7mA. According to the design, the width-to-length ratio of the M6 ​​tube is 1uM / 400nM, the width-to-length ratio of the M2 tube is 4uM / 400nM, and the finger number is 10. At this time, I DM6=0.7mA. According to the current mirror principle, the width-to-length ratio of M3 is 4uM / 400nM, the number of fingers is 20, and the width-to-length ratios of M4 and M5 are both 4uM / 400nM, and the number of fingers is 10. At this time, the output bias current Iref is 2.1mA and the output bias voltage is 0.62V. Considering the layout design and matching, for the switch tube M1, its width-to-length ratio is 4uM / 400nM, and the number of fingers is 5; for the switch tubes M7 and M8, its width-to-length ratio is 4uM / 400nM, and the number of fingers is 10; for the switch tube M10, its width-to-length ratio is 1uM / 400nM, and the number of fingers is 3; the decoupling capacitor C is 1pF.

[0020] Figure 3 For the layout of this embodiment, in order to achieve good layout matching and reduce the error caused by the manufacturing process, when designing the layout of the transistors constituting the current mirror circuit, the number of transistor fingers is 5 as the basic unit, and the current replication is achieved by changing the number of transistor multipliers. The layout area is about 70μm*30μm, and the layout occupies a small area, so for general amplifier circuits, it can be easily embedded in the final layout design.

[0021] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. For those skilled in the art, the present invention may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of the claims of the present invention.

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, the drain of transistor M1 is also connected to the drain of transistor M6, and 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 source of the transistor M1, the source of the transistor M2, the source of the transistor M3, the source of the transistor M4, and the source of the transistor M5 are all connected to VDD; The gate of the transistor M7 and the gate of the transistor M8 are connected to respective control voltages respectively; The drain of the transistor M9 is connected to the gate, the source of the transistor M9 is connected to the source of the transistor M10, the drain of the transistor M10 is connected to the gate of the transistor M9, the first end of the capacitor is connected to the gate of the transistor M9, and the second end of the capacitor is grounded; The control voltage connected to the gate of transistor M10 is the voltage of the control voltage connected to the gate of transistor M1 after passing through an inverter; The voltage outputted from the gate of transistor M9 serves as the bias voltage of the amplifier circuit.

2. The digital switch circuit based on 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 the transistors M7 and M8 are turned on, the source output currents of the transistors M4 and M5 are equal, and the current magnitudes are equal to the increase or decrease of the reference current Iref flowing into the source of the transistor M9 when the high and low temperatures change.

3. The digital switch circuit based on current mirror according to claim 2, characterized in that: When the high and low temperatures change, the reference current Iref flowing into the drain of the transistor M9 is kept stable by controlling the conduction states of the transistors M7 and M8.

4. The digital switch circuit based on current mirror according to claim 3, characterized in that: The amplifier is implemented using CMOS transistors. Specifically, the parasitic capacitance at the input end of the CMOS transistor is connected in series with the on-chip inductor at the input end to form a gate input artificial transmission line; the parasitic capacitance at the output end of the CMOS transistor is connected in series with the on-chip inductor at the output end to form a 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 achieve amplification of the input signal; Transistor M9 forms a current mirror with the CMOS transistors in the amplifier.

5. The digital switch circuit based on current mirror according to claim 4, characterized in that: According to the static operating point of the CMOS transistor in the amplifier, the width-to-length ratio of the M9 tube is adjusted, thereby adjusting the bias voltage of the amplifier circuit.

6. The digital switch circuit based on current mirror according to claim 5, characterized in that: The number of fingers of each transistor is based on 5 as the basic unit.

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