A variable gain amplifier

Abstract

The invention discloses a variable gain amplifier, including an attenuator, an amplifier, a reference voltage generator, a temperature compensation signal generator and two off-chip inductors; the attenuator is used to attenuate the input signal, and input the attenuated signal from the amplifier input end to the amplifier for amplification, and the amplified signal is output from the amplifier output end, the amplifier output end is respectively connected to one end of the two off-chip inductors, and the other end of the two off-chip inductors is grounded; the reference voltage generator is used to provide a reference voltage for the attenuator, and the temperature compensation signal generator provides a first control signal for the first-stage current source of the amplifier and a second control signal for the second-stage current source, thereby adjusting the current of the first-stage current source and the second-stage current source according to the on-chip temperature, and providing compensation for the temperature gain characteristics of the variable gain amplifier. The invention can achieve a wider bandwidth, a lower noise coefficient, a larger output 1dB compression point and a relatively stable gain at different temperatures.

Description

Technical Field

[0001] The invention belongs to the field of integrated circuit chips, and in particular relates to a variable gain amplifier. Background Art

[0002] Variable gain amplifiers are used in the receiving and transmitting links of communication or radar systems to adjust the gain of analog signals of varying magnitudes so that their amplitudes meet the requirements of subsequent circuits. Current variable gain amplifiers have problems such as narrow bandwidth, insufficient noise figure, small output 1dB compression point, and gain changes at different temperatures. Summary of the invention

[0003] The object of the present invention is to provide a variable gain amplifier capable of achieving a wider bandwidth, a lower noise figure, a larger output 1dB compression point and a relatively stable gain at different temperatures.

[0004] In order to achieve the above object, one aspect of the present invention provides a variable gain amplifier, comprising an attenuator, an amplifier, a reference voltage generator, a temperature compensation signal generator and two off-chip inductors.

[0005] The amplifier comprises an input transistor pair, a resistor load pair, a first-stage current source, a second-stage current source, an output MOS transistor pair and a temperature adjustment resistor pair;

[0006] One end of the resistor load pair is connected to the power supply voltage, and the other end is respectively connected to the collector of the input triode pair, the emitter of the input triode pair is connected to one end of the first-stage current source, the other end of the first-stage current source is grounded, the gate of the input triode pair is connected to the amplified output end, the collector of the input triode pair is connected to the gate of the output MOS tube pair, and is connected to one end of the temperature regulating resistor pair, and the other end of the temperature regulating resistor pair is connected to the drain of the output MOS tube pair and the amplified output end;

[0007] The attenuator is used to attenuate the input signal, and input the attenuated signal from the amplifier input end to the amplifier for amplification, and the amplified signal is output from the amplifier output end, the amplifier output end is respectively connected to one end of two off-chip inductors, and the other ends of the two off-chip inductors are grounded;

[0008] The reference voltage generator is connected to the attenuator and is used to provide a reference voltage for the attenuator. The temperature compensation signal generator is connected to the amplifier and is used to provide a first control signal for the first-stage current source of the amplifier and a second control signal for the second-stage current source, thereby adjusting the current of the first-stage current source and the second-stage current source according to the on-chip temperature to provide compensation for the temperature gain characteristics of the variable gain amplifier.

[0009] Preferably, the input transistor pair is NPN transistors, and the output MOS transistor pair is PMOS transistors.

[0010] Preferably, the temperature-adjusting resistor pair is a resistor having a positive temperature coefficient or a negative temperature coefficient.

[0011] The variable gain amplifier according to the above aspects of the present invention can achieve a wider bandwidth, a lower noise figure, a larger output 1 dB compression point and a relatively stable gain at different temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0013] Figure 1 is a block diagram of a variable gain amplifier according to an embodiment of the present invention;

[0014] Figure 2 1 is a circuit diagram of an amplifier according to an embodiment of the present invention. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] An embodiment of the present invention provides a variable gain amplifier, such as Figure 1 As shown, the variable gain amplifier of the embodiment of the present invention includes an on-chip attenuator, an amplifier (Amp), a reference voltage generator, a temperature compensation signal generator, and two off-chip inductors L1 and L2.

[0017] like Figure 2 As shown, the amplifier includes an input transistor pair N1, N2, a resistor load pair R1, R2, a first-stage current source I1 and a second-stage current source I2, an output MOS transistor pair M1, M2 and a temperature adjustment resistor pair R3, R4.

[0018] Among them, one end of the resistor load pair R1 and R2 is connected to the power supply voltage VDD, and the other end is respectively connected to the collector of the input transistor pair N1 and N2, the emitter of the input transistor pair N1 and N2 is connected to one end of the first-stage current source I1, the other end of the first-stage current source I1 is grounded, and the gate of the input transistor pair N1 and N2 is connected to the amplified output terminals VINP and VINN. The collector of the input transistor pair N1 and N2 is connected to the gate of the output MOS tube pair M1 and M2, and is also connected to one end of the temperature adjustment resistor pair R3 and R4, and the other end of the temperature adjustment resistor pair R3 and R4 is connected to the drain of the output MOS tube pair M1 and M2 and the amplified output terminals VOUTN and VOUTP.

[0019] The temperature adjustment resistor pair R3 and R4 may be resistors with positive temperature coefficients or negative temperature coefficients according to the circumstances.

[0020] The attenuator is used to attenuate the input signal, and input the attenuated signal from the amplifier input terminals VINN and VINP to the amplifier for amplification. The amplified signal is output from the amplifier output terminals VOUTP and VOUTN. The amplifier output terminals VOUTP and VOUTN are respectively connected to one end of two off-chip inductors L1 and L2, and the other ends of the two off-chip inductors L1 and L2 are grounded.

[0021] The reference voltage generator is connected to the attenuator to provide a reference voltage V1 for the attenuator. The temperature compensation signal generator is connected to the amplifier to provide a first control signal S1 for the first-stage current source I1 of the amplifier and a second control signal S2 for the second-stage current source I2, so as to adjust the currents of the two current sources according to the on-chip temperature, thereby providing compensation for the temperature gain characteristics of the entire variable gain amplifier.

[0022] During operation, the input signal is input to attenuator 1 for attenuation, and the attenuated signal is input to the amplifier from the amplifier input terminals VINN and VINP for amplification, and then output from the amplifier output terminals VOUTP and VOUTN. The reference voltage generator provides the reference voltage V1 for the attenuator, and the temperature compensation signal generator provides the first and second control signals S1 and S2 for the amplifier, thereby controlling the gain of the amplifier. The temperature adjustment resistor pair R3 and R4 also participate in the temperature compensation function.

[0023] Among them, the input transistor pair N1 and N2 are NPN transistors, and the output MOS transistor pair M1 and M2 are PMOS transistors.

[0024] The embodiment of the present invention can be used for a variable gain amplifier based on a germanium silicon process, and utilizes the good characteristics of the germanium silicon process to reasonably arrange the connection relationship of each component, has a simple structure, and an integrated design, and simultaneously achieves a wider bandwidth, a lower noise coefficient, a larger output 1dB compression point, and a relatively stable gain at different temperatures. Specifically, the variable gain amplifier of the embodiment of the present invention achieves a lower noise coefficient by using an NPN transistor at the input end, achieves a larger output 1dB compression point by using a PMOS transistor and an external inductor at the output end, and achieves a relatively stable temperature characteristic by current regulation of the first-stage current source I1 and the second-stage current source I2 and the resistance selection of the temperature regulating resistor pair R3 and R4.

[0025] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A variable gain amplifier, characterized in that: It includes an attenuator, an amplifier, a reference voltage generator, a temperature compensation signal generator, and two off-chip inductors. The amplifier comprises an input transistor pair, a resistor load pair, a first-stage current source, a second-stage current source, an output MOS transistor pair and a temperature adjustment resistor pair; One end of the resistor load pair is connected to the power supply voltage, and the other end is respectively connected to the collector of the input triode pair, the emitter of the input triode pair is connected to one end of the first-stage current source, the other end of the first-stage current source is grounded, the gate of the input triode pair is connected to the amplified output end, the collector of the input triode pair is connected to the gate of the output MOS tube pair, and is connected to one end of the temperature regulating resistor pair, and the other end of the temperature regulating resistor pair is connected to the drain of the output MOS tube pair and the amplified output end; The attenuator is used to attenuate the input signal, and input the attenuated signal from the amplifier input end to the amplifier for amplification, and the amplified signal is output from the amplifier output end, the amplifier output end is respectively connected to one end of two off-chip inductors, and the other ends of the two off-chip inductors are grounded; The reference voltage generator is connected to the attenuator and is used to provide a reference voltage for the attenuator. The temperature compensation signal generator is connected to the amplifier and is used to provide a first control signal for a first-stage current source of the amplifier and a second control signal for a second-stage current source, thereby adjusting the currents of the first-stage current source and the second-stage current source according to the on-chip temperature to provide compensation for the temperature gain characteristics of the variable gain amplifier. The input transistor pair is an NPN transistor, the output MOS transistor pair is a PMOS transistor; the temperature adjustment resistor pair is a resistor with a positive temperature coefficient or a negative temperature coefficient.

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