JP5287439B2 - Voltage-current conversion gain controller, voltage-current conversion gain control method, and radio apparatus - Google Patents

Description

  The present invention relates to a voltage / current conversion gain controller having a variable voltage / current conversion gain, a voltage / current conversion gain control method, and a radio apparatus.

It is known that a voltage / current conversion gain controller is used in a high-frequency circuit in a wireless device.
In recent years, in wireless communication such as portable wireless terminals and wireless local area networks (LANs), the frequency handled is widened, multi-channels, and communication modes are becoming multi-mode, and the frequency is arranged from a wide frequency range to a fine frequency pitch. It is necessary to control the frequency characteristics of the high-frequency circuit so that the spectrum to be selected can be selected. The high-frequency circuit requires a filter that can flexibly control the frequency characteristics in order to remove the interference wave component and select the required spectrum.

A Gm-C filter circuit is an example of a filter that can control the frequency characteristics. The Gm-C filter circuit can obtain a desired frequency characteristic by combining the transconductance Gm and capacitance C of the voltage-current conversion gain controller and selecting those values.
In the voltage / current conversion gain controller controlled in an analog manner, it is difficult to widen the control range of the transconductance Gm. Therefore, in a Gm-C filter circuit using an analog-controlled voltage-current conversion gain controller, a plurality of filter circuits showing necessary frequency characteristics are prepared in advance, and a filter circuit to be used is selected from them. It was configured as follows. For this reason, circuits that are not selected at the same time are mounted, and when the number of frequency characteristics to be selected increases, a large number of filters are formed, and a large mounting area is required. In addition, it takes time to adjust the characteristics of each filter circuit.

An example of a voltage-current conversion gain controller that is digitally controlled instead of analogly controlled is shown.
In an example of a digitally controlled voltage-current conversion gain controller, the transconductance Gm is divided into a plurality of voltage-current conversion units, and the voltage-current conversion units are activated by connecting the voltage-current conversion units in parallel. There is one that sets a desired capacity by controlling the number (see Patent Document 1).

JP 2004-528798 A

  However, according to the configuration described in Patent Document 1, the voltage-current conversion gain is set by combining a plurality of voltage-current conversion units connected in parallel. In order to increase the accuracy of the voltage-current conversion gain to be set, it is necessary to combine a number of finely divided voltage-current conversion units. When the number of divisions increases, the mounting area increases. If it is realized with a limited area, the number of divisions is limited, and precise voltage-current conversion gain cannot be set. In addition, in order to apply to a filter circuit with good frequency selection characteristics, a filter having a high-order attenuation characteristic is required, and thus a Gm-C filter needs to be configured in multiple stages. Such a filter has a problem that it is difficult to realize it using a configuration in which the circuit scale per stage is increased.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a voltage / current conversion gain controller and a voltage / current conversion gain control method capable of varying the voltage / current conversion gain with high accuracy or in a wide range. The present invention also provides a wireless device to which a voltage-current conversion gain controller is applied.

 In order to solve the above problem, the present invention provides a voltage-current conversion gain controller capable of controlling a voltage-current conversion gain, the first voltage-current conversion unit having a first maximum voltage-current conversion gain, A second voltage-current conversion unit having a second maximum voltage-current conversion gain set to a predetermined magnification predetermined with respect to the first maximum voltage-current conversion gain is connected in parallel, and the first and second The voltage-current conversion gains of the first and second voltage-current converters are independently controlled according to the first and second duty ratios of the clocks respectively supplied to the voltage-current converters, and are controlled independently. The voltage-current conversion gain controller is characterized in that a voltage-current conversion gain corresponding to the output current converted by the voltage-current conversion gain and added is set.

In order to solve the above problem, the present invention provides a voltage-current conversion gain controller capable of controlling a voltage-current conversion gain, the first voltage-current conversion unit having a first maximum voltage-current conversion gain, A second voltage-current converter having a second maximum voltage-current conversion gain set to be larger than the first maximum voltage-current conversion gain at a predetermined magnification predetermined with respect to the first maximum voltage-current conversion gain ; Are connected in parallel, and the voltage-current conversion of the first and second voltage-current converters according to the first and second duty ratios of the clocks respectively supplied to the first and second voltage-current converters The gain is controlled independently, the voltage-current conversion gain is combined with the value obtained by adding the voltage-current conversion gain , and the first voltage-current conversion unit is supplied with a clock based on the first duty ratio. The second The voltage-current converter is supplied with a clock based on a second duty ratio controlled independently of the first clock, and the first duty ratio is finely set with respect to the second duty ratio. This is a voltage-current conversion gain controller characterized by being capable .

The present invention also relates to a voltage-current conversion gain control method for a voltage-current conversion gain controller including a plurality of piezoelectric current conversion units, wherein the plurality of voltage-current conversion gain control units are connected in parallel and the maximum voltage-current conversion gain is set to a predetermined magnification. The voltage-current conversion gain of the voltage-current conversion unit is independently controlled according to the duty ratio of the clock supplied to each of the voltage-current conversion units, and the value obtained by adding the voltage-current conversion gain to each value. A voltage-current conversion gain is synthesized, and a first clock based on the first duty ratio is supplied to the voltage-current conversion unit having the smallest maximum voltage-current conversion gain among the voltage-current conversion units, and the other A second clock based on a second duty ratio controlled independently of the first clock is supplied to the voltage-current converter, and the first duty ratio is set to the second duty ratio. To the ratio, the voltage-current conversion gain control method, which is a possible set finely.

It is a block diagram which shows the voltage current conversion gain controller by this embodiment. It is a schematic block diagram which shows the voltage current conversion part in the same embodiment. It is a waveform which shows the clock supplied to the voltage-current converter in the same embodiment. It is a block diagram which shows the voltage current conversion part in the embodiment. It is a figure which shows the waveform of the clock supplied to the voltage current conversion part in the embodiment. It is a figure which shows the voltage current conversion gain of the voltage current conversion part in the same embodiment.

Hereinafter, a voltage-current conversion gain controller according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram illustrating the voltage-current conversion gain controller according to the present embodiment.
The voltage / current conversion gain controller 100 includes a voltage / current conversion circuit 10 and a signal generation circuit 20.
The voltage-current converter circuit 10 includes a plurality of voltage-current converters 11, 12, 13, and 14 (in the case of being collectively referred to as “voltage-current converter 1n”).
The voltage-current converter 1n in the voltage-current conversion gain controller 100 performs voltage-current conversion according to the input voltage _VIN , and outputs the converted current.

FIG. 2 shows a configuration example of the voltage-current converter 1n.
The voltage _VIN input to the terminal 111 is converted into a current by the voltage-current conversion gain set in the voltage-current conversion unit 113, and the current is output via the SW unit 114. The SW unit 114 performs switching according to the clock CLK input from the signal generation unit 20.
When the pulse of the clock CLK indicates a high level, and conducting the SW section 114, according to the time of the pulse width T _ON is longer, execution value of the current to be output increases.
The duty ratio φ in the clock _CLK is defined by the ratio (T _ON / T _CLK ) of the pulse width T _ON to the clock period T _CLK (see FIG. 3).

FIG. 4 further shows specific configurations of the voltage / current converter 113 and the SW unit 114.
The voltage-current converter 113 can be a CMOS inverter in which two field effect transistors (FETs) are combined.
In the voltage-current converter 113, the drain current of the FET is controlled according to the input voltage _VIN , and the output current is set.
The SW unit 114 can be an FET switch in which two field effect transistors (FETs) are combined. The SW unit 114 is supplied with an inverted clock CLK_INV obtained by inverting the clock CLK and the clock CLK. The SW unit 114 becomes conductive when the clock CLK is at a high level and the inverted clock CLK_INV is at a low level, and outputs the current output from the voltage-current conversion unit 113 to obtain an output current I _OUT .

Returning to FIG. 1, the operation of the voltage / current converters 11 to 14 will be described.
The voltage-current converters 11 to 14 have different maximum voltage-current conversion gains for converting the input voltage into current, and have values of maximum voltage-current conversion gains MGm1 to MGm4, respectively. Further, the voltage-current converter 1n can be reduced to a set voltage-current conversion gain. The voltage / current conversion gains VGm1 to VGm4 set in the voltage / current conversion units 11 to 14 are respectively duty ratios φ1 to φ4 (referred to as “clock CKn” in the collective description) of the clocks CK21 to CK24 supplied. When collectively shown, it is referred to as “duty ratio φn”).
Duty ratio φn in the clock CKn is indicated by the ratio of the pulse width _{T ON} to the period _{T CLK} of respective clock (see FIG. 3).
The voltage-current conversion gains VGm1 to VGm4 have the relationship shown in the equation (1).

VGm1 = MGm1 × φ1,
VGm2 = MGm2 × φ2,
VGm3 = MGm3 × φ3,
VGm4 = MGm4 × φ4 (1)

The voltage-current converter 1n in the voltage-current converter circuit 10 has an input terminal connected to the terminal TB1 and an output terminal connected to the terminal TB2. The voltage-current converter 1n receives clocks CK21 to CK24 (referred to as “clock CK2n” when collectively shown) from the signal generation circuit 20.
The signal generation circuit 20 in the voltage-current conversion gain controller 100 divides the input clock CLKIN to generate and output clocks CK21 to CK24 indicated by the frequency fs. The clocks CK21 to CK24 output the clock clocks CK21 to CK24 indicated by the set duty ratios φ1 to φ4 (referred to collectively as “duty ratio φn”) with respect to the clock CLKIN.

Examples of clocks output to the clocks CK21 to CK24 will be described with reference to the drawings.
FIG. 5 is a waveform showing a clock set to the clock CKn.
This figure shows waveforms when the respective duty ratios φn are set to 100%, 75%, 50%, and 25%. When the transconductance at each duty ratio is expressed as Gm ₁₀₀ , Gm ₇₅ , Gm ₅₀ , and Gm _{25 based} on the transconductance Gm ₀ at 100%, the following equation (2) is obtained.

Gm ₁₀₀ = 1 × Gm _0,
Gm ₇₅ = 0.75 × Gm ₀ ,
Gm ₅₀ = 0.5 × Gm ₀ ,
Gm ₂₅ = 0.25 × Gm ₀ (2)

  In this way, the transconductance setting can be changed by changing the duty of the input clock.

Returning to FIG. 1, the transconductance VGm set in the voltage-current conversion gain controller 100 will be described.
At this time, the transconductance VGm synthesized by the action of each voltage-current converter 1n is expressed by Equation (3).

  VGm = VGm1 + VGm2 + VGm3 + VGm4 (3)

In Expression (3), VGm1 to VGm4 indicate voltage-current conversion gains in the respective voltage-current conversion units 11 to 14.
Here, for the values of the maximum voltage current conversion gains MGm1 to MGm4, the values of the maximum voltage current conversion gains MGm2 to MGm4 are expressed by powers of 2 with reference to the maximum voltage current conversion gain MGm1 of the voltage current conversion unit 11 That is, it is set in order of 2 times, 4 times and 8 times. Formula (1) can be converted into Formula (4) according to the definition of the set magnification.

VGm1 = MGm1 × 1 × φ1,
VGm2 = MGm1 × 2 × φ2,
VGm3 = MGm1 × 4 × φ3,
VGm4 = MGm1 × 8 × φ4 (4)

  Then, when Expression (4) is substituted into Expression (3), Expression (5) is derived.

  VGm = MGm1 (1 × φ1 + 2 × φ2 + 4 × φ3 + 4 × φ4) (5)

Subsequently, the duty of each clock in the voltage-current conversion gain controller 100 shown by the above configuration is determined, and the change in transconductance VGm at that time is shown.
FIG. 6 is a correspondence table showing the relationship between the duty set for each clock and the transconductance VGm of the voltage-current conversion gain controller 100.
Here, the duty φ1 of the clock CK21 is selected from five values (0, 0.25, 0.5, 0.75, 1). The duty φ2 of the clock CK22, the duty φ3 of the clock CK23, and the duty φ4 of the clock CK24 are selected from three values (0, 0.5, 1). The duties φ1 to φ4 shown here can be set independently, and a value represented by the reciprocal of a power of 2 is selected.

The value of the duty φn of each clock CKn is indicated by an array indicated by (φ4, φ3, φ2, φ1).
The condition for setting the largest transconductance VGm is when all the values of the duty φn of each clock CKn are set to “1”. That is, in terms of arrangement, it is (1, 1, 1, 1), and the transconductance VGm in that case is 15.0 times the basic maximum voltage-current conversion gain MGm1.
The next largest transconductance VGm is set when the value of the duty φn of each clock CKn is (1, 1, 1, 0.75), and the transconductance VGm at that time is the basic maximum This is 14.75 times the voltage-current conversion gain MGm1.
The transconductance VGm when the value of the duty φn of each clock CKn is (1, 1, 0.5, 1), (1, 0.5, 1, 1) is the basic maximum voltage current. 14 times and 13 times the conversion gain MGm1.

Conversely, the condition for setting the smallest transconductance VGm is when the value of the duty φn of each clock CKn is (0, 0, 0, 0.25). The transconductance VGm in that case is basically The maximum voltage-current conversion gain MGm1 is 0.25 times.
The condition for setting the next smallest transconductance VGm is when the value of the duty φn of each clock CKn is (0, 0, 0, 0.5), and the transconductance VGm in that case is the basic maximum It becomes 0.5 times the voltage-current conversion gain MGm1.
The transconductance VGm when the value of the duty φn of each clock CKn is (0, 0, 0, 1), (0, 0, 0.5, 1) is the basic maximum voltage-current conversion gain. 1x and 2x MGm1.
By selecting each value shown in the figure, it is possible to easily change the magnification from 0.25 times to 15 times at equal intervals of 0.25 times from a limited combination of duty ratios. Show.

Here, a voltage-current conversion gain controller 300 by a voltage-current conversion circuit 30 in which the voltage-current conversion unit 1n is configured by one voltage-current conversion unit 11 is assumed and compared with the voltage-current conversion gain controller 100.
The voltage / current conversion circuit 30 in the voltage / current conversion gain controller 300 connects a pair of transconductances Gm and a capacitance C via a switch, and controls the time during which the switch is turned on / off to control the transconductance Gm _300. Get.
The transconductance Gm ₃₀₀ of the voltage-current conversion gain controller ₃₀₀ is shown as (Gm × φ) and is determined by the duty ratio φ of the input clock.
In the voltage-current conversion gain controller 300, the duty ratio φ is set stepwise, and the number of settable values is increased to ensure the accuracy of the transconductance Gm set to the stepped value. When the number of stages of duty ratios that can be set cannot be increased, the number of stages of transconductance Gm _{300 that} can be selected decreases, and it is difficult to ensure accuracy.

  In contrast to the voltage-to-current conversion gain controller 300, the voltage-to-current conversion gain controller 100 described above can ensure accuracy even if the number of steps for setting the duty ratio φ is set to be small. FIG. 5 shows an example in which the number of stages set for each duty ratio φ is 5 or less. In the voltage / current conversion gain controller 100, weighting is performed with the magnification set to the maximum voltage / current conversion gains MGm1 to MGm4. Further, a value equal to or larger than the magnification is set to the number of stages that can be set to the duty ratios φ1 to φ4. Then, by combining the maximum voltage / current conversion gains MGm1 to MGm4 and the duty ratios φ1 to φ4, the transconductance VGm can be set in fine steps as shown in FIG.

In the above embodiment, in the voltage / current conversion gain controller 100, the voltage / current conversion unit 11 having the maximum voltage / current conversion gain MGm1 and a predetermined magnification (2 ⁿ ) predetermined for the maximum voltage / current conversion gain MGm1. Are connected in parallel to voltage-current converters 12 to 14 having maximum voltage-current conversion gains MGm2 to MGm4 set to. The voltage / current conversion gains VGm1 to VGm4 of the voltage / current conversion units 11 to 14 are independently set according to the duty ratio φ1 and the duty ratios φ2 to φ4 of the clocks supplied to the voltage / current conversion unit 11 and the voltage / current conversion units 12 to 14, respectively. The voltage-current conversion gain VGm is combined with the values obtained by adding the voltage-current conversion gains VGm1 to VGm4.
Thereby, the current values output from the voltage-current converters 11 to 14 connected in parallel can be added, and the current output from the voltage-current converters 11 to 14 set to a predetermined magnification is It is controlled to a value obtained by multiplying the duty ratios φ1 to φ4, and by adding the respective currents, the voltage-current conversion gain VGm can be set in fine steps, and the effective value of the voltage-current conversion gain VGm can be set with high accuracy or It can be varied over a wide range.

The voltage-current converter 11 is supplied with a clock CK21 based on the duty ratio φ1, and the voltage-current converters 12-14 are clocks CK22-24 based on a duty ratio φ2-4 controlled independently of the clock CK21. Is added to the product of the duty ratio φ1 and the maximum voltage current conversion gain MGm1, and the product of the duty ratio φ2 (to φ4) and the maximum voltage to current conversion gain MGm2 (to MGm4). Is set to the derived value.
Thereby, it is possible to set the transconductance VGm in fine steps by combining the magnification set to the maximum voltage-current conversion gains MGm1 to MGm4 and the duty ratios φ1 to φ4.

In the maximum voltage-current conversion gains MGm2 to MGm4, a predetermined magnification predetermined for the maximum voltage-current conversion gain MGm1 is a magnification determined by a power of 2 (2 ⁿ ).
As a result, the maximum voltage-current conversion gains MGm2 to MGm4 can be set to a predetermined magnification according to the value indicated by the binary number, and an error caused at the time of calculation by being controlled by the duty ratio indicated by the reciprocal number of the binary number. Can be reduced.

The duty ratios φ1 to φ4 are values determined by the reciprocals of powers of 2.
Thus, by multiplying the voltage-current conversion gain set according to the value represented by the binary number by the duty ratio represented by the reciprocal number of the binary number, it is possible to reduce the influence of the error that occurs during the calculation.

The maximum voltage-current conversion gain MGm2~MGm4 is at a predetermined ratio which is predetermined with respect to the maximum voltage-current conversion gain MGm1, at a power of two powers of 10 instead of the value indicated by ^{(2 n)} (10 ⁿ⁾ You can also select and set the value shown. In this case, the duty ratio φn of the clock CK2n set is 10 decimal steps by 0.1 pitch (0.1, 0.2,..., 0.9, 1). It becomes easy to control with the indicated value.
As a result, the maximum voltage-current conversion gains MGm2 to MGm4 can be set to a predetermined magnification according to the value indicated by the decimal number, and an error caused at the time of calculation by being controlled by the duty ratio indicated by the inverse number of the decimal number. Can be reduced.

In the radio apparatus, a Gm-C filter circuit to which the voltage / current conversion gain controller 100 is applied can be applied to a receiving circuit or the like.
As a result, the Gm-C filter circuit can be selected in fine steps even when the capacitance C is fixed by adopting a configuration in which the voltage-current conversion gain controller 100 capable of controlling the voltage-current conversion gain in fine steps is applied. The frequency to be set can be set. By applying such a Gm-C filter circuit to a filter circuit in a high frequency circuit of a wireless device and extracting a spectrum selected by the filter circuit, an arbitrary spectrum can be selected from a wide frequency band. Become.

The present invention is not limited to the above embodiments, and can be modified without departing from the spirit of the present invention.
In the voltage-current conversion gain controller according to the present invention, any type of voltage-current conversion circuit can be used as the voltage-current conversion circuit, and the number and configuration of the voltage-current conversion circuits are not particularly limited. Absent.

  The voltage / current conversion gain controller of the present invention corresponds to the voltage / current conversion gain controller 100. The voltage-current conversion circuit of the present invention corresponds to the voltage-current conversion circuit 10. The voltage / current converter of the present invention corresponds to the voltage / current converters 11, 12, 13, and 14.

DESCRIPTION OF SYMBOLS 100 Voltage current conversion gain controller 10 Voltage current conversion circuit 11, 12, 13, 14 Voltage current conversion part 20 Signal generation circuit

Claims (7)

A voltage-current conversion gain controller capable of controlling a voltage-current conversion gain,
A first voltage-current conversion unit having a first maximum voltage-current conversion gain; and a predetermined magnification that is predetermined with respect to the first maximum voltage-current conversion gain, and is set to be larger than the first maximum voltage-current conversion gain And a second voltage-current converter having a second maximum voltage-current conversion gain, connected in parallel, and first and second clocks supplied to the first and second voltage-current converters, respectively. The voltage-current conversion gains of the first and second voltage-current converters are independently controlled according to the duty ratio, and the voltage-current conversion gains are combined into values obtained by adding the voltage-current conversion gains ,
The first voltage-current converter is
A clock based on the first duty ratio is provided;
The second voltage-current converter is
A clock based on a second duty ratio controlled independently of the first clock is provided;
The voltage-current conversion gain controller, wherein the first duty ratio can be finely set with respect to the second duty ratio . Voltage-current conversion gain that is pre-Symbol synthesis,
The product of the first duty ratio and the first maximum voltage / current conversion gain, and the product of the second duty ratio and the second maximum voltage / current conversion gain are set to a derived value. The voltage-current conversion gain controller according to claim 1. The voltage / current conversion gain controller according to claim 1, wherein the predetermined magnification predetermined for the first maximum voltage / current conversion gain is a magnification determined by a power of two. The voltage-current conversion gain controller according to any one of claims 1 to 3, wherein the first and second duty ratios are values determined by reciprocals of powers of two. 3. The voltage-current conversion gain controller according to claim 1, wherein the predetermined magnification predetermined with respect to the first maximum voltage-current conversion gain is a magnification determined by a power of 10. 4. A voltage-current conversion gain control method of the voltage-current conversion gain controller comprising a plurality of voltage power current conversion unit,
The voltage-current conversion gains of the voltage-current converters are independently set according to the duty ratio of the clocks respectively supplied to a plurality of voltage-current converters connected in parallel and having the maximum voltage-current conversion gain set to a predetermined magnification. The voltage-current conversion gain is combined with a value derived by controlling and adding the voltage-current conversion gain,
In the voltage-current converter having the smallest maximum voltage-current conversion gain among the voltage-current converters,
A first clock based on the first duty ratio is provided;
In the other voltage-current converter,
A second clock based on a second duty ratio controlled independently of the first clock is provided;
A voltage-current conversion gain control method characterized in that the first duty ratio can be finely set with respect to the second duty ratio . A radio apparatus using a filter circuit to which the voltage-current conversion gain controller according to claim 1 is applied.

Images