TW589784B - Linear-in-decibel variable gain amplifier - Google Patents

Abstract

A linear-in-decibel variable gain amplifier comprises: an amplifying stage, for generating an output voltage according to a differential input voltage; and a gain-controlling stage, for outputting a gain-controlling voltage to the amplifying stage according to a first controlling voltage and a second controlling voltage. A voltage gain of the linear-in-decibel variable gain amplifier is inverse proportional to a simple exponential function, and the value of the simple exponential function is determined by the difference between the first controlling voltage and the second controlling voltage.

Description

589784 V. Description of the invention (1). TECHNICAL FIELD OF THE INVENTION The present invention provides a variable gain amplifier, especially an exponential gain type variable gain amplifier. Previous technologies Due to the booming development of infinite communication systems in recent years, various high-frequency and high-sensitivity transceiver architectures have been proposed successively. In order to increase the dynamic processing range of the system to increase the sensitivity of the system, a variable gain amplifier (Var i ab 1 e Ga i n Amp 1 i f er, VGA) is often used as the main circuit for processing dynamic gain control. And the voltage gain for the control voltage ... ·.-The exponential variable gain amplifier is the architecture with the largest dynamic range processing capability. Please refer to FIG. 1. FIG. 1 is a circuit diagram of a conventional variable gain amplifier. Figure 1 is a form of a differential amplifier (differentia 1 ampl ifi er), so you can know the voltage gain of the entire circuit only by looking at the part of the half circuit. If the issue of phase is not considered, the voltage gain (voltage gain) Αν can be expressed as Equation 1 using the following equation: Av = Vout / Vin: K / [l + exp (Vy / Vl :)] where K is substantially a certain value. From Equation 1, we know that

Page 6 589784 V. Description of the invention (2) The value is determined by a differential gain control voltage V y. Because the denominator part of the voltage gain A v is not a purely exponential function, it also has the existence of a constant term 1, which results in the relationship of the voltage gain Av with respect to the control voltage Vy is not a true exponential linear relationship. Please refer to Figure 2. Figure 2 shows the relationship between the voltage gain and the control voltage according to Equation 1. When V y < V tB, the voltage gain Α ν does not change exponentially linearly due to the change in the control voltage Vy. At this time, the voltage gain curve will gradually flatten, and the main reason for the flattening is because it is The denominator part of the equation has the existence of a constant term 1, which causes the voltage gain Aν to have a truly linear exponential relationship curve with respect to the control voltage Vy. SUMMARY OF THE INVENTION Therefore, the main object of the present invention is to provide a variable gain amplifier in which the voltage gain has a simple exponential relationship with the control voltage. Can a power system based on power generation system benefit control system greatly increase and increase control, a pressure reduction number and pressure increase the number of electricity refers to the increase of power one to one, according to one of the pressure and the transmission of electrical appliances to open the road to make a big announcement. The level of control and amplifier for electric difference: one system benefits, and the big data increases. The surrounding system changes and the model changes. One call out can be useful. The control level of the number of devices is very large, and the second one is to release the first profit and the first one to increase the data. Outgoing, the root pressure transformer i

Page 7 589784 V. Description of the invention (3) Inversely proportional to a simple exponential function, wherein the value of the simple exponential function is determined by the difference between the first control voltage and the second control voltage. According to the embodiment of the present invention, the gain control circuit includes a transduction unit, a first current conversion unit, a second current conversion unit, and an output unit. The gain control circuit can generate a gain control voltage according to a first control voltage and a second control electric house, so as to control one of the voltage gains of the amplifier circuit '...'... 'For implementation methods, please refer to FIG. 3 is a block diagram of a circuit of an exponential gain type variable gain amplifier according to an embodiment of the present invention. The exponential gain type variable gain amplifier 300 includes an amplifying stage circuit 30 2 for determining a voltage gain according to a gain control voltage V y, that is, a ratio of a wheel-in voltage (V i η) to an output voltage (Vout). ; And a gain control circuit 304 for controlling the magnitude of the gain control voltage Vy. · · · In this embodiment, the circuit of the amplifier stage circuit 302 is the same as the conventional variable gain amplifier described above. Please refer to Figure 1 and the corresponding description above, which will not be repeated here. Please refer to Equation 1. The magnitude of the voltage gain of the amplifier circuit 302, that is, the ratio of the differential output voltage (Vout) to the differential input voltage (Vi η), is determined by the gain control voltage (Vy).

589784 V. Description of the invention (4) Please refer to FIG. 4 and FIG. 5, which are circuit diagrams of the f-increasing control circuit 304 according to the embodiment of the present invention. The gain control circuit 3 04 is used to determine the magnitude of the gain control voltage Vy to be output to the amplifier circuit 3 2 according to the first control voltage V 1 and the second control voltage V 2. Among them, the gain control circuit r includes: transduction The unit 40 includes a first current conversion unit 403, a second current conversion unit 40 5 (FIG. 4), and an output unit 4 07 (FIG. 45). The detailed description will be described below. ....................... : The first transistor 472 is coupled to the first control voltage Π; the second transistor 473 is coupled to the second control voltage V2; the first bias current source I bi as is consumed by the first transistor 472 and the second transistor The emitter of the crystal 473 is used to provide the first bias current 113451; the first current source 4 0 2; the first resistor R i is coupled to the collector of the first transistor 4 7 2 and the first current source 4 0 2; and the second resistor R 2 is coupled between the collector of the second transistor 4 7 3 and the first current source 4 0 2. The magnitude of the collector current II flowing through the second transistor 473 is determined by the difference between the first control voltage VI and the second control voltage V2 and the first bias current Ibiasl. In this embodiment, the relationship is shown by the following equation: Equation 2: Il = Ibiasl / {l + exp [(Vl-V2) / Vt]} Since the transduction unit 4 0 1 is a differential circuit, Therefore, the relationship between the collector current flowing through the first transistor 4 7 2 and the first control electric dust v 1, the second control voltage V 2, and the first bias current Ibiasl is similar to that of Equation 2.

Page 9 589784 V. Description of the invention (5) The positions of V 1 and V 2 need to be reversed. ..-.... ''.,.... 'The first current conversion unit 403 is coupled to the transduction unit 401 by using the second current source 404, and includes: a third transistor 474, whose collectors are connected together. At the base; the fourth transistor 475; the second bias current source 11 ^ 332, coupled to the emitter of the third transistor 474 and the fourth transistor 475, for providing a second bias current I bias 2; The second current source 4 0 4; the third resistor R 3 is connected between the collector of the third transistor 4 7 4 and the second current source 4 0 4; the fourth resistor R 4 is connected to the fourth current Between the collector of the crystal 475 and the second current source 404. The second current source 40 and the first current source 402 form a current mirror circuit. In this embodiment, the ratio of the collector current I 2 of the third transistor 474 and the collector current Ί 1 of the second transistor 4 7 3 to the first bias current Ibiasl and the second bias current Ibia > The ratio of 2 is proportional, as shown in the following Equation 3: Equation 3: I 2/11 = I bias 2 / I bias 1 Since the first current conversion unit 40 3 is also a differential circuit, and according to Equation 3, The relationship between the collector current 12 of the third transistor 474 and the collector current I 1 of the second transistor 4-7. Therefore, the collector current of the fourth transistor 4 7 5 and the third transistor The proportional relationship between the collector current 12 of the crystal 474 is the same as the proportional relationship between the collector current of the first transistor 472 and the collector current 11 of the second transistor 473. When the first bias current Ibiasl is equal to the second bias current Ibias2, the collector current of the first transistor 472 is equal to the fourth transistor

Page 10 589784 V. Description of the invention (6) The collector current of 4 7 5 and the collector current I 1 of the second transistor is equal to the collector current I 2 of the third transistor. The second current conversion unit 405 includes: The fifth transistor 4 7 6 has a base and a collector that are lightly connected to the base of the fourth transistor 4 7 5, and the sixth transistor 4 7 7 ′ has a base coupled to the base of the third transistor 4 7 4 And collector; and a ninth transistor 480, and the emitter of the fifth transistor 476 and the sixth transistor 477, respectively........ To provide a third bias current Ibias3. According to the circuit relationship formed by the third transistor ...... body 474, the fourth transistor 475, the fifth transistor 476, and the sixth transistor 4 7 7, it can be known that the sixth transistor The ratio of the collector current 13 of 4 7 6 to the collector current 12 of the third transistor 474 will be proportional to the ratio of the third bias current I bias 2 and the first bias current I bias 1. Show: Equation 4: I 3 / I 2 = I bi as3 / I bi as 2 Because the second current conversion unit 40 5 is also a differential circuit, and according to Equation 4, the third transistor 4 7 4 is a collection The relationship between the pole current 12 and the collector current 13 of the sixth transistor 477, therefore, the proportional relationship between the collector current I 4 of the fifth transistor 47 6 and the collector current I 3 of the sixth transistor 4 7 7 and The ratio of the collector current of the fourth transistor 4 75 to the collector current 12 of the third transistor 474 is the same. Therefore, from Equation 2, Equation 3, and Equation 4, we can see that

Page 11 589784 V. Description of the invention (7) The circuit is essentially a voltage controlled current amplifier circuit (Vo 11age—Control led-Current-Amp 1 if i er). By controlling the difference between the differential input voltages, that is, the difference between the first control voltage V 1 and the second control voltage V 2, the proportional relationship between the output currents 13 and 14 can be controlled. The relationship is shown in the following Equation 5: Equation 5: I 4 / I 3 = Kx e X p [(V 1-V 2) / V t]

The output unit 4 shown in FIG. 5 includes: a seventh transistor 4 7 8 whose base is coupled to the collector; an eighth transistor 479; and a fourth bias current source 14, which is respectively connected to the seventh transistor The emitters of 478 and the eighth transistor 4 79 are coupled. It should be noted that the voltage-controlled current amplifying circuit in FIG. 4 and the input unit 407 in FIG. 5 are respectively connected to two current mirror circuits (not shown), so that the magnitude of the bias current output by the fourth bias current source is equal to The collector current 14 of the fifth transistor 4π is such that the collector current 13 of the sixth transistor 47 7 is equal to the collector current I 3 of the seventh transistor 4 7 8. Although the current mirror circuit is shown in the figure, anyone skilled in this art can easily know its electricity, form and coupling relationship according to Figure 4 and Figure 5. Thus, the collector current of the seventh transistor 4 7 8 is equal to the collector current I 3 of the sixth transistor 4 7 7 and the collector current of the eighth transistor 4 7 9 is equal to the collector of the fifth transistor 4 7 6 The difference between the pole current I 4 and the collector current I 3 of the sixth transistor 4 7 7. The bases of the seventh transistor 4 7 8 and the eighth transistor 4 7 9 are used to interface with the amplifier circuit 302 shown in FIG. 1 to output the gain control voltage Vy. Therefore, the gain control voltage Vy and the collector current 13 of the seventh transistor 478 and the collector current of the eighth transistor 479 (14-13)

589784 V. Description of the invention (8) The relationship of * is as shown in the following Equation 6.................... Equation V .. Vy = Vtx ln [(I4 -I3) / I3] = Vtx 111 (14/134) '·..., Circle, ....' In summary, the gain control circuit 304 is based on the input first control voltage 'V 1 and The difference between the first control voltage v 2 determines the current proportional relationship in the differential circuit of each stage, and determines the magnitude of the gain control voltage vy input to the amplifier circuit 3 2 according to the current proportional relationship. Combining the above-mentioned Equation 5 and Equation 6, it can be known that the relationship between the gain control voltage Vy and the first control voltage VI and the second control voltage V2 of the gain control circuit 304 proposed in this embodiment is shown in the following Equation 7: ... ......: Equation 7: Vy = Vtx in {Kx exp [(Vl_V2) / Vt] -1}-. ·. ·..--Gain control using the above gain control circuit 3 0 4 output The voltage Vy is used as the control voltage Vy of the amplifier circuit 3 2 in FIG. 1, and then the voltage gain generated by the amplifier circuit 302, that is, the ratio of the output voltage to the input voltage, will be shown in the following Equation 8: Equation 8: Av = Voiit / Vin = Kl / exp [K2 (Vr-V2)] where K1 is related to the output resistance RL of the amplifier circuit 3 0 2 and K2 is related to the thermal voltage of the bipolar transistor (Bipolar Junctiοη Transistor, BJT) (thermal vo 1 tage, VT), in the present invention, K1 and K2 are essentially

589784 V. Description of the invention (9) " ------ All can be regarded as constant 〆 ^ ^ ^ ^ ^^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ / 3 required f. The above-mentioned gain control circuit 304 is only one example of the present invention. Ranfeng invention is not limited to this. Any circuit that can make the value of the output voltage ^ V y proportional to η (^ a / j b-κ 3) is within the scope of the present invention. Among them, κ 3 is constant, and the magnitude of ^ is corresponding to the first control voltage vi, and the magnitude of Ib is corresponding to the second control voltage V2. '., .....;-•'.... From Equation 8, it can be seen that the gain control circuit 3 0 makes the voltage gain Δν of the amplifier circuit 30 2 and the first control voltage vi and the second control. The difference (V1-V2) of the voltage V2 m has a simple exponential function relationship κι / νχρ [κ2 (η-V2)]. Please refer to FIG. 6, which is a relationship curve of the voltage gain with respect to the first and second control voltages according to Equation 8. Compared with the relationship graph of FIG. 2, it can be seen that the voltage gain Δν of FIG. 6 has a simple exponential relationship with the difference between the first control voltage VI and the second control voltage V2. In addition, the amplifier circuit 302 has two input terminals for receiving a differential type input voltage. In addition, the output voltage of the exponential gain type variable gain amplifier proposed by the present invention may be a single-ended output or a double-ended output for outputting a differential type output voltage. Of course, the amplifier circuit used in the present invention does not have to be the amplifier circuit shown in FIG. 1, as long as it is the same as the amplifier circuit in FIG. 1, the denominator of the voltage gain is not a simple exponential function, and it also includes

Page 14 589784 V. Description of the invention (ίο) A variable gain amplifier circuit with a pseudo-constant term can be used with the gain control circuit provided by the present invention to achieve the effect of the present invention. Han

Please apply for the application of Shenli, and send the text clearly. Every response should be an example. The decoration should be better and better.

Page 15 · 589784 Simple explanation of the diagram Simple explanation of the diagram... Figure 1 is a circuit diagram of the variable gain amplifier of the conventional technology. Figure 2 is a plot of the relationship between voltage gain and control voltage for Equation 1. FIG. 3 is a block diagram of an embodiment of an exponential gain type variable gain amplifier according to the present invention. FIG. 4 is a partial circuit diagram of an embodiment of the gain control circuit 304. FIG. 5 is a partial circuit diagram of an embodiment of the gain control circuit 304. Fig. 6 is a graph showing the relationship between the voltage gain and the first and second control voltages in accordance with Equation 8. Explanation of symbols in the figure 30 0 Exponential gain type variable gain amplifier 30 2 Amplifier stage circuit 304 Gain control circuit 401 Transduction unit 40 First current source 40 3 First current conversion unit 40 4 Second current source 40 5 Two current conversion unit 40 7 output unit 472 first transistor

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Claims (1)

589784 VI. Scope of patent application 1. A variable gain amplifier comprising: an amplifier stage circuit for outputting an output voltage based on a differential input voltage; and a gain control circuit for using a first control voltage And a first-control voltage outputs a gain control voltage to the amplifying stage circuit, so that a voltage gain of the variable gain amplifier is inversely proportional to a simple exponential function, and the value of the simple exponential function is determined by the first control voltage and This second control voltage is determined by the difference.丄 2. The variable gain amplifier described in item 1 of the scope of patent application, the amplifier stage circuit has an electrical waste gain, and the denominator is in the form of (Kl + exp (K2 X Vy)), where K1 And K2 is a constant, Vy is the gain control voltage: 乂 ::. 2 ^ 3. The variable gain amplifier according to item 2 of the patent application range, wherein the gain control voltage is a differential form ^ 4. The variable gain amplifier according to item 1 of the scope of patent application, wherein the gain control circuit includes: a transduction amplifier unit for outputting a first current and a first current according to the first control voltage and the second control voltage; Two currents, wherein the ratio of the first current and the second current is related to the difference between the first control voltage and the second control voltage; a current conversion unit is coupled to the transconductance amplifier unit and outputs One Page 18 589784 VI. Patent application scope A third current corresponds to the first current, and a fourth current corresponds to the second current; and an output unit is coupled to the current conversion unit to The third current and the fourth current output the gain control voltage; wherein the gain control voltage is determined by a difference between the first control voltage and the second control voltage. 5. The variable gain amplifier according to item 4 of the scope of patent application, wherein the relationship between the first current and the second current and the first control voltage and the second control voltage is: 11/12 = exp (Kx (Vl-V2)), where 11 is the first current, 12 is the second current, VI is the first control voltage, and V2 is the second control voltage. 6. The variable gain amplifier according to item 5 of the scope of patent application, wherein the magnitude of the third current is equal to the first current, and the magnitude of the fourth current is equal to the second current. -V- 7. The variable gain amplifier as described in item 5 of the patent application range, wherein the gain control voltage is proportional to 1η (Ι1 / Ι2-Κ3), where 1 (3 is a constant. 8. The variable gain amplifier according to item 4 of the scope of patent application, wherein the transconductance amplifier unit includes: a first transistor coupled to the first control voltage L Page 19 589784 VI. Patent application Fan Jie-a second transistor coupled to the second control voltage; and a first bias current source coupled to the emitter of the first transistor and the second transistor The emitter is used to provide a first bias current; t, the first transistor system outputs the first current according to the first control voltage and the first bias current, and the second transistor system is based on the The second control voltage and the first bias current output the second current. 9. The variable gain amplifier according to item 4 of the scope of the patent application, wherein the output unit includes: a third transistor having a collector connected to the base surface and a collector current corresponding to the fourth current A fourth transistor and a second bias current source, the emitter of the first transistor and the emitter of the second transistor are used to provide a second bias current; The second bias current corresponds to the third current; and the base of the third transistor and the fourth transistor is used to output the gain control voltage. Page 20 589784 VI. The scope of the patent application is as follows, including a large package, a Yuanyuan single replacement, changeable, and convertible electricity. One of the first one 4 · · Fan Li, please apply for a single replacement In the turning Haishi φ, there is a Hai JH port and a body crystal. The electrodes are based on the following: 'in the coupling electrode: the coupling set, its source ,; The first guide and the transfer of the •, and the liquid crystal of the piezoelectricity, the fifth one, the first one, and the supply, are divided by the source, the current, the fourth, the first, the sixth, and the sixth, the single crystal, The current seven is connected to the electric unit, and the second unit is connected to the first unit. The unit is included. The sixth unit should be coupled to the pole set and the base unit. The fifth unit should be connected to the unit; In this case, the four-electrode body of the electric body should be used for the eighth electric power, the first one should be used as the base, and the body pole base 基 -νδ and the body crystal. The current seventh power should be biased to the four-in-one coupling, and the source should be used to increase the voltage to the electricity. Page 21