Broadband radio frequency amplifier with high 1dB compression point

Abstract

The invention relates to the field of semiconductor integrated circuit design, in particular to a broadband radio frequency amplifier with a high 1dB compression point, which comprises an input matching stage circuit, a negative feedback circuit, an active biasing circuit, an amplifying circuit and an output matching stage circuit. According to the invention, by introducing the common-base transistor which is grounded through the capacitor, the linearity of the amplifier is improved; by constructing an active bias structure, the working current of the amplifier at different temperatures is more stable, the linearity of the amplifier is further improved, and the output 1dB compression point parameter of the amplifier is improved.

Description

Technical Field

[0001] The invention relates to the field of semiconductor integrated circuit design, and in particular to a broadband radio frequency amplifier with a high 1dB compression point. Background Art

[0002] In recent years, 5G communications have developed rapidly and have been used in various social fields. 5G communications usually use high-output power and high-linearity RF amplifiers to pre-amplify the front-stage signal. Higher linearity means that while the input power is increased, there is less nonlinear distortion in the communication system.

[0003] In order to meet the demand for high output power, traditional RF amplifiers mainly increase the output power of the amplifier by increasing the operating current of the amplifier. Increasing the operating current will cause temperature changes. Both high and low temperature states will cause the operating voltage point to shift, thereby amplifying the drift of the operating current by the same amount. Current drift causes the performance parameters of the amplifier, such as power gain and output power, to differ greatly from those at normal temperature, and also brings about the problem of poor linearity of the amplifier.

[0004] Therefore, designing a high-power RF amplifier with more stable operating current and higher linearity has important practical engineering value. Summary of the invention

[0005] In view of this, the present invention proposes a broadband RF amplifier for improving the high-frequency 1dB compression point to solve the above-mentioned problems; it includes: an input matching stage circuit, a negative feedback circuit, an active bias circuit, an amplification circuit, and an output matching stage circuit.

[0006] Among them, the input matching stage circuit includes input matching stage circuit port 1 and input matching stage circuit port 2; the negative feedback circuit includes negative feedback circuit port 1, feedback circuit port 2 and negative feedback circuit port 3; the active bias circuit includes active bias circuit port 1 and active bias circuit port 2; the amplifier circuit includes amplifier circuit port 1, amplifier circuit port 2 and amplifier circuit port 3; the output matching stage circuit includes output matching stage circuit port 1, output matching stage circuit port 2 and output matching stage circuit port 3.

[0007] Further, the input matching stage circuit port 1 serves as an input terminal, the input matching stage circuit port 2 is respectively connected to the negative feedback circuit port 1 and the amplifier circuit port 3, the feedback circuit port 2 is connected to the active bias circuit port 1, the negative feedback circuit port 3 is respectively connected to the amplifier circuit port 1 and the output matching stage circuit port 1, the active bias circuit port 2 is connected to the amplifier circuit port 2, the output matching stage circuit port 2 serves as a power supply terminal, and the output matching stage circuit port 3 serves as an output terminal.

[0008] The beneficial effects of the present invention include: by introducing a common base transistor grounded by a capacitor, the linearity of the amplifier is improved; by constructing an active bias structure, the operating current of the amplifier at different temperatures is more stable, the linearity of the amplifier is further improved, and the output 1dB compression point parameter of the amplifier is improved. In addition, in a typical embodiment, compared with the traditional structure, the broadband RF amplifier implemented by the circuit structure of the present invention has an output 1dB compression point parameter that is improved by 1.2dBm within a frequency of 1GHz, and the output power drops more slowly with increasing frequency. At a frequency of 8GHz, the output 1dB compression point parameter is improved by 2.4dBm, the third-order intermodulation cutoff point is improved by 1.7dBm, and the fluctuation value of the high and low temperature current values ​​compared with the normal temperature is reduced by 6mA. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A modular schematic diagram of a broadband radio frequency amplifier for improving a high-frequency 1dB compression point in the present invention;

[0010] Figure 2 A circuit diagram of a broadband radio frequency amplifier for improving a high-frequency 1dB compression point in the present invention;

[0011] Figure 3 This is a typical Darlington amplifier circuit diagram;

[0012] Figure 4 The output 1dB compression point of the broadband RF amplifier with improved high-frequency 1dB compression point in the present invention varies with frequency.

[0013] Figure 5 This is a curve diagram of current variation versus temperature of a broadband radio frequency amplifier that improves the high-frequency 1dB compression point in the present invention. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution, characteristics and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0015] This embodiment includes: an input matching stage circuit, a negative feedback circuit, an active bias circuit, an amplifier circuit, and an output matching stage circuit. Figure 1 shown.

[0016] Among them, the input matching stage circuit includes input matching stage circuit port 1 and input matching stage circuit port 2; the negative feedback circuit includes negative feedback circuit port 1, feedback circuit port 2 and negative feedback circuit port 3; the active bias circuit includes active bias circuit port 1 and active bias circuit port 2; the amplifier circuit includes amplifier circuit port 1, amplifier circuit port 2 and amplifier circuit port 3; the output matching stage circuit includes output matching stage circuit port 1, output matching stage circuit port 2 and output matching stage circuit port 3.

[0017] Further, the input matching stage circuit port 1 serves as an input terminal, the input matching stage circuit port 2 is respectively connected to the negative feedback circuit port 1 and the amplifier circuit port 3, the feedback circuit port 2 is connected to the active bias circuit port 1, the negative feedback circuit port 3 is respectively connected to the amplifier circuit port 1 and the output matching stage circuit port 1, the active bias circuit port 2 is connected to the amplifier circuit port 2, the output matching stage circuit port 2 serves as a power supply terminal, and the output matching stage circuit port 3 serves as an output terminal.

[0018] Furthermore, the input matching stage circuit includes components: capacitor C in ; C in The two ends serve as input matching stage circuit port 1 and input matching stage circuit port 2 respectively.

[0019] Furthermore, the negative feedback circuit includes the following elements: a resistor R 1 , resistor R 2 , capacitor C 1 ; Among them, R 2 One end of the negative feedback circuit is used as the interface 1, R 2 The other end is connected to R 1 One end of C 1 One end, R 1 The other end is connected to C 1 The other end serves as the negative feedback circuit interface 3, R 1 With R 2 The connected common terminal serves as port 2 of the negative feedback circuit.

[0020] Further, the active bias circuit includes the following elements: transistor Q 1 , resistor R 3 , resistor R 4 , capacitor C 2 ; Among them, Q 1 The collector of the active bias circuit acts as port 1, Q 1 The emitter is connected to R 3 one end of Q 1 The bases of 4 One end of C 2 One end, R 3 The other end of the capacitor C 2 The other end is connected to ground, R 4 The other end serves as the active bias circuit port 2.

[0021] Furthermore, the amplifier circuit includes the following components: transistor Q 2 , transistor Q 3 , transistor Q 4 , resistor R 5 , resistor R6 , resistor R 7 , capacitor C 3 ; Among them, Q 2 The collectors are connected to R 6 One end and Q 4 The collector of the amplifier circuit acts as port 1, Q 2 The emitters are connected to R 5 One end and Q 3 The base of the amplifier circuit is used as port 2, Q 2 The base of the amplifier circuit is port 3, Q 3 The collector of Q 4 The emitter, R 5 The other end of R 7 One end is connected to ground, Q 3 The emitter is connected to R 7 On the other end, Q 4 The bases of 3 One end and R 6 The other end, C 3 The other end is grounded.

[0022] Furthermore, the output matching stage circuit includes components: capacitor C out , inductance L 1 Among them, C out One end is connected to L 1 One end of the output matching circuit is used as port 1, C out The other end is used as output matching stage circuit port 3, L 1 The other end serves as port 2 of the output matching stage circuit.

[0023] Among them, the transistor Q 1 , transistor Q 2 and transistor Q 3 GaAs HBT transistors are used.

[0024] Furthermore, if Figure 2 The circuit diagram of the broadband RF amplifier used in this embodiment to improve the high frequency 1dB compression point is shown. Figure 3 The RF amplifier structure based on the Darlington amplification structure is shown.

[0025] The transistor Q 3 The collector of the newly added transistor Q 4 The emitter of transistor Q 4 The collector and circuit output RF out Through this structure, a common base amplifier is added compared to the original structure, and the RF signal passes through the transistor Q 3After amplification, it passes through transistor Q 4 Reach the output end. This increases the output power, improves the 1dB compression point parameter, and increases the output impedance. While increasing the output power, the current generated by the DC bias is transferred by the transistor Q 4 With Q 3 The working current is basically unchanged compared with the original structure. The output power is improved without changing the working current of the original structure. With the increase of frequency, the output 1dB compression point parameter decreases more slowly, which improves the working bandwidth of the RF amplifier. Under the same power, the working current of the circuit proposed by the present invention is more stable.

[0026] To improve the temperature drift problem caused by increasing the output power, an active bias structure is added: In the typical Darlington amplifier structure, the resistor R 1b and resistor R 2b The power supply voltage at the output end is divided according to the resistance ratio to provide transistor Q 1b The base voltage to ground; due to R 1b and R 2b The ratio of will not change when the temperature changes, and the voltage at the input end will not change with the temperature change; further, when the temperature rises, the BE junction voltage drop V be As the temperature increases, the resistance R 3b and R 4b As the voltage on the circuit increases, the operating current of the entire circuit also increases with the increase of temperature. Figure 2 As shown, transistor Q 2 The base voltage is determined by the resistor R 1 , resistor R 2 , resistor R 3 and transistor Q 1 Common determination; transistor Q 1 The collector of 2 Connect to transistor Q 2 The base of transistor Q 1 The base of the 4 Connect to transistor Q 3 Specifically, when the temperature rises, due to the transistor Q 1 The active bias structure formed makes the transistor Q 2 and transistor Q 3 The base voltage of the resistor R 5 and resistor R 7 The voltage rise at both ends due to the temperature rise, and the total current change in the circuit is reduced.

[0027] Furthermore, compared with the typical Darlington amplifier structure, the bias transistor Q 1 A capacitor C connected in series to ground is added at the base position of 2 , in transistor Q 4 The voltage divider resistor connected in series with the ground is changed to a capacitor C connected to the ground port. 3 The two ends of the transistor base have the effect of capacitors in series, the impedance is increased, and the voltage value is more stable. For AC signals, the signal path to the ground is increased, the linearity of the input RF signal is improved, and the output third-order intermodulation point parameters are improved, thereby improving the linearity of the amplifier and the high and low temperature working stability.

[0028] Furthermore, in the test of the circuit shown in this embodiment, if Figure 4 As shown, the output 1dB compression point parameter is improved by 1.2dBm within 1GHz frequency; the output power drops more slowly with increasing frequency, and the output 1dB compression point parameter is improved by 2.4dBm at 8GHz frequency; the third-order intermodulation cutoff point is improved by 1.7dBm; the broadband RF amplifier of the present invention has higher linearity. Figure 5 As shown, the fluctuation value of the current value at high temperature and low temperature is reduced by 6mA compared with that at normal temperature. The working current of the broadband RF amplifier of the present invention is less affected by temperature and is more stable.

[0029] Finally, it should be noted that the above only describes some embodiments of the present invention. For those skilled in the art, it is conceivable that various changes, modifications, substitutions and deformations may be made to these embodiments without departing from the principles and spirit of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents, and the above-mentioned actions should be covered within the scope of protection of the present invention.

Claims

1. A broadband radio frequency amplifier with a high 1dB compression point, characterized in that: include: Input matching stage circuit, negative feedback circuit, active bias circuit, amplifier circuit, output matching stage circuit; Among them, the input matching stage circuit includes input matching stage circuit port 1 and input matching stage circuit port 2; the negative feedback circuit includes negative feedback circuit port 1, feedback circuit port 2 and negative feedback circuit port 3; the active bias circuit includes active bias circuit port 1 and active bias circuit port 2; the amplifier circuit includes amplifier circuit port 1, amplifier circuit port 2 and amplifier circuit port 3; the output matching stage circuit includes output matching stage circuit port 1, output matching stage circuit port 2 and output matching stage circuit port 3; Among them, the input matching stage circuit port 1 serves as the input end, the input matching stage circuit port 2 is respectively connected to the negative feedback circuit port 1 and the amplifier circuit port 3, the feedback circuit port 2 is connected to the active bias circuit port 1, the negative feedback circuit port 3 is respectively connected to the amplifier circuit port 1 and the output matching stage circuit port 1, the active bias circuit port 2 is connected to the amplifier circuit port 2, the output matching stage circuit port 2 serves as the power supply end, and the output matching stage circuit port 3 serves as the output end.

2. The broadband RF amplifier for improving high frequency 1dB compression point according to claim 1, characterized in that: The input matching stage circuit includes components: capacitor C in ; Among them, C in The two ends serve as input matching stage circuit port 1 and input matching stage circuit port 2 respectively.

3. The broadband RF amplifier for improving high frequency 1dB compression point according to claim 1, characterized in that: The negative feedback circuit includes components: resistor R1, resistor R2, capacitor C1; Among them, one end of R2 serves as negative feedback circuit interface 1, the other end of R2 is connected to one end of R1 and one end of C1 respectively, the other end of R1 is connected to the other end of C1 and serves as negative feedback circuit interface 3, and the common end connected to R1 and R2 serves as negative feedback circuit port 2.

4. The broadband RF amplifier for improving high frequency 1dB compression point according to claim 1, characterized in that: The active bias circuit includes components: transistor Q1, resistor R3, resistor R4, capacitor C2; Among them, the collector of Q1 serves as the active bias circuit port 1, the emitter of Q1 is connected to one end of R3, the base of Q1 is connected to one end of R4 and one end of C2 respectively, the other end of R3 is connected to the other end of capacitor C2 and grounded, and the other end of R4 serves as the active bias circuit port 2.

5. The broadband RF amplifier for improving high frequency 1dB compression point according to claim 1, characterized in that: The amplifier circuit includes components: transistor Q2, transistor Q3, transistor Q4, resistor R5, resistor R6, resistor R7, capacitor C3; Among them, the collector of Q2 is respectively connected to one end of R6 and the collector of Q4 and serves as amplifier circuit port 1, the emitter of Q2 is respectively connected to one end of R5 and the base of Q3 and serves as amplifier circuit port 2, the base of Q2 serves as amplifier circuit port 3, the collector of Q3 is connected to the emitter of Q4, the other end of R5 is connected to one end of R7 and grounded, the emitter of Q3 is connected to the other end of R7, the base of Q4 is respectively connected to one end of C3 and the other end of R6, and the other end of C3 is grounded.

6. The broadband RF amplifier for improving high frequency 1dB compression point according to claim 1, characterized in that: The output matching stage circuit includes components: capacitor C out , inductor L1; Among them, C out One end is connected to one end of L1 and serves as output matching stage circuit port 1, C out The other end serves as output matching stage circuit port 3, and the other end of L1 serves as output matching stage circuit port 2.

7. The broadband RF amplifier for improving high frequency 1dB compression point according to claim 1, characterized in that: The transistor Q1, the transistor Q2 and the transistor Q3 are all GaAs HBT transistors.

Images