JP4877564B2 - Full-wave rectifier circuit - Google Patents

Description

  The present invention relates to a full-wave rectifier circuit using an integrated circuit, and more particularly to a full-wave rectifier circuit having a circuit configuration suitable for CMOS-LSI implementation.

  A full-wave rectifier circuit using an integrated circuit can be easily configured by using a bipolar process. However, with the recent high integration and low power consumption, the MOS process has become mainstream, and it is important to configure the circuit by the MOS process.

  FIG. 3 is a block diagram showing an example of a full-wave rectifier circuit using a conventional MOS process. A differential input circuit 201 surrounded by a thin line inputs an AC signal Vin, a current subtraction circuit 202 subtracts a constant current from a pair of output currents of the differential input circuit 201, and a current addition circuit 203 is a pair of current subtraction circuits 202. Add the output current.

  FIG. 4 is a waveform showing the relationship between the current of each transistor shown in FIG. 3 and the AC signal Vin. First, when an AC signal Vin (see FIG. 4A) is input to the differential input circuit 201, currents i and (I1-i) flow in the transistors Tr21 and Tr22, respectively (FIGS. 4B and 4B). C)).

These currents are mirrored to the transistors Tr25 and Tr26 of the current subtraction circuit 202 by the transistors Tr23 and Tr24, respectively, so that a current subtracted by I2 / 2 flows through the transistors Tr27 and Tr28. That is, if the current flowing through the transistor Tr27 is I (Tr27) and the current flowing through the transistor Tr28 is I (Tr28),
I (Tr27) = i-I1 / 2
I (Tr28) = I1−i−I1 / 2 = − (i−I2 / 2)
It becomes.

  Actually, however, I (Tr27) <0 when i <I1 / 2, and I (Tr28) <0 when i> I1 / 2, so that no current flows through the transistors Tr27 and Tr28. (See FIGS. 4D and 4E).

  Finally, the currents flowing through the transistors Tr27 and Tr28 are mirrored to the transistors Tr29 and Tr30 of the current adding circuit 203 and added by the transistor Tr31, thereby obtaining a full-wave rectified waveform as shown in FIG. The transistor Tr32 is an output transistor.

  However, in the full-wave rectifier circuit shown in FIG. 3, since the output current is determined by the mutual conductance Gm of the transistors Tr21 and Tr22 of the differential input circuit 201, the amplitude of the output current varies due to process variations of the transistors. (See dotted line in Fig. 4 (F)). Further, when an output voltage is obtained using a resistor, the output voltage amplitude changes due to manufacturing variations of resistance values and temperature fluctuations even if the output current is constant.

JP-A-8-289554

  The problem to be solved is that it is impossible to prevent characteristic deterioration due to manufacturing variations of circuit elements and temperature fluctuations.

  The most important feature of the present invention is that a resistor is inserted between the drains of the differential input transistor so that the current flowing through the differential input circuit is determined by the resistance.

  In the full wave rectifier circuit of the present invention, a resistor is inserted between the drains of the differential input transistor, and the current flowing through the differential input circuit is determined by the resistance regardless of the amplification factor of the transistor. By taking the relative accuracy between the voltage-current conversion resistor and the resistor when the output of the rectifier circuit is taken out as a voltage, there is an advantage that the output voltage can be kept constant even if these fluctuations occur.

It is a circuit diagram which shows one Example of the full wave rectifier circuit of this invention. It is a wave form diagram of the full wave rectifier circuit shown in FIG. It is a circuit diagram which illustrates the conventional full wave rectifier circuit. It is a wave form diagram which shows the operation | movement of the full wave rectifier circuit shown in FIG.

  FIG. 1 shows a first embodiment of a full-wave rectifier circuit according to the present invention. This full-wave rectifier circuit includes a differential input circuit 101, a current subtraction circuit 102, and a current addition circuit 103. The differential input circuit 101 receives an alternating current signal and outputs a differential current superimposed on a constant current (its value is written as I0 like the constant current source I0). The current subtracting circuit 102 subtracts a constant current from the current mirrored from the differential input circuit 101 and outputs a differential current, but outputs a zero value in a time domain where the subtraction result is negative. The current adding circuit 103 obtains an output current that has been full-wave rectified by adding two differential currents that are 180 degrees different in phase from the current subtracting circuit 102. Now, the current flowing through the transistors Tr1 and Tr2 will be described as (I0-i) and (I0 + i).

  The differential input circuit 101 is a resistor that converts the differential voltage into a differential current i by connecting the transistors Tr1 and Tr2 that generate the differential voltage by differential input of the AC signal Vin and the drains of the transistors Tr1 and Tr2. R1, the constant current source I0 connected to the respective drains of the transistors Tr1 and Tr2, and the currents (I0-i) and (I0 + i) obtained by superimposing the differential currents on the constant currents are represented by Tr4 and Tr7 in the current subtraction circuit 102. Transistors Tr3 and Tr6 that mirror the current. The direction of the differential current i is the direction from the drain of the transistor Tr1 to the drain of the transistor Tr2.

  Now, if the potential difference between the drains and gates of the transistors Tr1 and Tr2 is made equal, the potential difference between the drains of the transistors Tr1 and Tr2, that is, the both ends of the resistor R1, becomes an AC signal Vin, so the current flowing through the resistor R1 is i = Vin / R1 is determined by R1.

  The current subtracting circuit 102 generates and outputs differential currents 2i and -2i from the current mirrored current (I0 + i) and current (I0-i) from the differential input circuit 101. The generation of the differential current 2i is performed by the transistors Tr4, Tr7, Tr9, Tr10, and Tr11. On the other hand, the differential current -2i is generated by the transistors Tr5, Tr13, Tr14, Tr15, and Tr16. The generation of the differential current is performed by subtraction by branching the current path as described below.

  First, current mirrored currents (I0-i) and (I0 + i) from the transistors Tr3 and Tr6 of the differential input circuit 101 are received by the transistors Tr4 and Tr7. The transistor Tr9 mirrors the current (I0-i) of the transistor Tr4 to the transistor Tr10. The transistor Tr11 generates a differential current 2i by subtracting the current (I0-i) of the transistor Tr10 from the current (I0 + i) of the transistor Tr7.

  Further, the current mirrored currents (I0-i) and (I0 + i) from the transistors Tr3 and Tr6 of the differential input circuit 101 are also received by the transistors Tr5 and Tr15. The transistor Tr13 mirrors the current (I0-i) of the transistor Tr5 to the transistor Tr14. The transistor Tr16 generates a differential current -2I1 by subtracting the current (I0 + i) of the transistor Tr15 from the current (I0-i) of the transistor Tr14.

  As described above, the differential currents 2I1 and -2I1 are generated with the same circuit configuration. However, the current mirror of the differential currents 2i and -2i to the current adding circuit 103 is performed with different circuit configurations. That is, the differential current -2i is directly mirrored from the transistor Tr16 to the transistor Tr17 of the current adding circuit 103, whereas the differential current 2i is supplied from the transistor Tr11 to the transistor Tr12 and the transistor Tr8 through the current adding circuit. The current is mirrored to 103 transistor Tr18.

  This is because the current mirror can only be performed between MOSs of the same polarity. In the former, both the transistor Tr16 and the transistor Tr17 are NMOS, whereas in the latter, the transistor Tr11 is a PMOS and the transistor Tr18 is an NMOS. Therefore, the current of the PMOS transistor Tr11 is current-mirrored to the PMOS transistor Tr12, and is serially connected to the transistor Tr12. The connected NMOS transistor Tr8 takes over, and this current is mirrored to the NMOS transistor Tr18.

  In the current adding circuit 103, the differential current 2i flowing through the transistor Tr18 and the differential current -2i flowing through the transistor Tr17 are added together to flow to the transistor Tr19, and the transistor Tr19 adds the differential currents 2i,- 2i is current mirrored to the transistor Tr20. Differential currents 2i and -2i flowing through the transistor Tr20 are output currents.

  As described above, the current i flowing through the resistor R1 is determined by R1. Therefore, when a current-voltage conversion resistor (not shown) is connected to the transistor Tr20 to obtain an output voltage obtained by multiplying the output current, it is manufactured by taking the relative accuracy between the resistor R1 and the current-voltage conversion resistor. Even if there are variations and temperature fluctuations, the output voltage can be kept constant. In addition, taking relative accuracy means making a predetermined dimensional ratio correspond among several things, and can implement | achieve easily by manufacturing in the same process.

  Next, the operation of the full-wave rectifier circuit configured as described above will be described with reference to the waveform diagram shown in FIG. First, as shown in FIG. 2A, when the AC signal Vin is input to the differential input circuit 101, the current flowing through the transistor Tr1 is as shown in FIG. 2B, and the current flowing through the transistor Tr2 is as shown in FIG. In addition, the waveform is 180 degrees out of phase.

  Now, when the AC signal Vin, that is, the input voltage of the transistor Tr1, rises, if the differential current flowing through the resistor R1 is set to i, the current (I0-i) flowing through the transistor Tr1 decreases and the current flowing through the transistor Tr2 ( I0 + i) increases.

The current (I0-i) flowing through the transistor Tr1 and the current (I0 + i) flowing through the transistor Tr2 are current mirrored to the current subtracting circuit 102 and subjected to subtraction processing. As a result, if the current flowing through the transistor Tr11 is i (Tr11) and the current flowing through the transistor Tr16 is i (Tr16),
i (Tr11) = 2i
i (Tr16) =-2i
It becomes. However, since the transistor flows current only in one direction, i (Tr16) = 0. The waveforms of i (Tr11) and i (Tr16) are shown in FIGS. 2 (D) and 2 (E).

  Next, when the AC signal Vin, that is, the input voltage of the transistor Tr1 is lowered, the direction of the differential current I1 flowing through the resistor R1 is opposite to that in FIG. 1, so that the current (I0-i) flowing through the transistor Tr1 increases. The current (I0 + i) flowing through the transistor Tr2 decreases. In this case, (I0-i) and (I0 + i) and i (Tr11) and i (Tr16) in the above description may be interchanged.

  Finally, i (Tr11) and i (Tr16) are current mirrored to the transistors Tr18 and Tr17 of the current adder circuit 103 and added by the transistor Tr19 to obtain a full-wave rectified current. The current flowing through the transistor Tr19 is current-mirrored to the transistor Tr20 and can be taken out as an output voltage by flowing it through a current-voltage conversion resistor.

  In this case, as described above, if the relative accuracy of the resistor R1 and the current-voltage conversion resistor are matched, it is possible to suppress deviations in absolute values due to manufacturing variations of the resistors and temperature fluctuations. That is, the manufacturing variation and temperature variation of the resistor R1 coincide with the manufacturing variation and temperature variation of the current-voltage conversion resistor. Since these fluctuations act in opposite directions with respect to the current and voltage, even if the current flowing through the transistor Tr20 is fluctuated by the resistor R1, as shown in FIG. Since they are canceled out, the magnitude of the output voltage can always be kept constant as shown in FIG.

101, 201 Differential input circuit
102, 202 Current subtraction circuit
103, 203 Current addition circuit
Vin input signal
I0 constant current source
Tr1-Tr32 transistor
R1 resistance

Claims (2)

A full wave rectifier circuit,
A differential input circuit that inputs an AC signal and outputs a differential current superimposed on a constant current; and
A current subtracting circuit for subtracting the constant current from a current mirrored from the differential input circuit to output a differential current;
A current adding circuit that obtains a full-wave rectified output current by adding two differential currents that are 180 degrees different in phase from the current subtracting circuit;
Between the drains of the differential input transistors in the differential input circuit, insert a resistor such that the value of the flowing current is determined by the value,
The value of the resistor is obtained by matching a predetermined dimensional ratio in the manufacturing process between the output current and the value of the resistor multiplied to obtain the output voltage of the full-wave rectifier circuit. Wave rectifier circuit.   2. The full-wave rectifier circuit according to claim 1, wherein a voltage between a drain and a gate of two transistors that input the AC signal is equal in the differential input circuit.

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