TWI281780B - Transconductance amplifier with tail current control and anti-aliasing filter with temperature-compensated - Google Patents

Abstract

This invention is related to a transconductance amplifier with tail current control and an anti-aliasing filter (AAF) with temperature-compensated. The anti-aliasing filter utilizes a temperature-compensated circuitry to provide a bias voltage to an active LC ladder filter so as to neutralize tail current drifting caused by the temperature variation. Besides, a regulator with cascode bandgap circuitry is utilized to supply a stable voltage to suppress the variations of power and temperature. Therefore, the 3 dB bandwidth of the anti-aliasing filter can be stable even on various temperature.

Description

1281780 IX. Description of the Invention: [Technical Field] The present invention relates to an operational transconductance amplifier and an anti-aliasing filter, and more particularly to an operational transconductance amplifier with tail current control and temperature-resistant compensation Distortion filter. [Prior Art]

Referring to Figure 1, the general filter basic architecture is composed of passive LC components. Figure 1 shows a sixth-order passive inductor-capacitor step filter. However, since the inductance components are often very large, it is not conducive to cost reduction. With the advancement of circuit integration technology, recent designs have replaced passive RLC components with active circuits. Active circuits include: operational amplifiers or operational transconductance amplifiers. Referring to FIG. 2, the conventional operational transconductance amplifier mainly adopts the previous % [1] (B. Nauta " A CMOS Transconductance-C Filter Technique for

Veiy High Frequencies, " IEEE J. Solid-State Circuits, v〇l. 275 no. 2, pp 142-153, Feb. 1992.) Circuit design. Cypress H Gan" electric rafter. However, its electro-crystalline system and electricity are very susceptible to noise and temperature change. That is, it is compatible with the ground potential, and it becomes interference, and the reliability is not high. In addition, the characteristics of the filter are based on the values of the passive components described above, so the stability of the passive components dominates the characteristics of the entire filter. Generally designed m contains the frequency calibration circuit, which is not only complicated at the design level, but also has poor resistance to temperature drift, and it is not beneficial, such as the prior art [2] (Chen Yongtai, "Equation

Zhou is used for the new Q-value calibration circuit of Gm-C filter for Q-value continuous-time. "National Gentleman and +13⁄4 Lishan University, Department of Electrical Engineering 104891.doc 1281780 Master's thesis, 2 〇〇9 〉βj丄w straight 4 [3] (Republic of China patent announcement road "). - or turn (four) (four) wave 11 frequency adjustment back _ automated Q value adjustment circuit to adjust circuit characteristics (such as the first financial technology (1)). However, obviously Ground, in the circuit design is complex and high. & w field operation transduction, therefore, it is necessary to provide an innovative and progressive large time and anti-aliasing filter to solve the above problems. Mingzhi - the purpose is to provide an operational transconductance amplifier with tail current control, ... at least six inverters and at least six taillights: a transistor. /, an inverter is respectively connected to a first electric a second input terminal, a second voltage input terminal, a first voltage output terminal, and a second voltage output terminal. The six tail current transistors are respectively connected to the corresponding inverters and the ground terminal. The tail current electro-crystal system is controlled by a reference voltage. The transconductance amplifier with the tail current control is controlled by the current of the inverter on the front end of the inverter, to control the tail current (taUeujTent), so that the bias current of the converter and the amplifier is limited. It is not affected by the drift of temperature, and does not have a drastic effect. Another object of the invention is to provide a temperature-compensated anti-aliasing filter, an active inductor-capacitor step filter, a temperature , the south] shell circuit and the voltage regulator. The active inductor _ capacitor stepped filter package symmetrical active inductor, at least one capacitor and at least one active resistor, 5 hp active inductor _ capacitor step filter for The input signal filters the artifact frequency (image Frequenc). The temperature compensation circuit provides a 104891.4 1281780 reference voltage to the active inductor-capacitor step filter to stabilize the active inductor-capacitor step filter. dB bandwidth. The voltage regulator is used to provide a stable power supply to the dynamic inductor-capacitor step filter and the temperature compensation circuit. The anti-aliasing filter of the present invention utilizes the Compensation circuit to stabilize the bias current changes due to the temperature drift caused, to reduce the effects of temperature drift caused by the circuit, thus achieving a stable filter, filter, bias current, so that this

The 3rd bandwidth of the inventive anti-aliasing filter remains stable even at different operating temperatures. [Embodiment] Referring to Fig. 3', there is shown a block diagram of a temperature-compensated anti-aliasing filter of the present invention. The anti-distortion (4) with temperature compensation of the present invention comprises: an active inductor-capacitor step filter 31, a temperature compensation circuit 32 and a voltage regulator 33. The active inductor-capacitor step filter 31 can refer to the sixth-order inductor-capacitor step ladder filter circuit (6th_〇rder Active ladder filter). The active inductor-capacitor step filter of the present invention 3 1 replaces the conventional passive inductor and passive resistor in the circuit of Figure 1 with an active inductor and an active resistor. Therefore, the active inductor-capacitor stepped filter 31 includes at least one symmetric active inductor, at least one capacitor, and at least one active resistor, and the enchanting inductor-capacitor ladder is used to filter the input signal by the artifact. Frequency (Image Frequency). Referring to Figure 4, an equivalent circuit diagram of the active inductor is shown. The symmetrical active inductor 40 includes at least four symmetrical transconductance amplifiers, operative, 4 0 3 and 4 0 4 and at least 'one round Φ lei female p » pull out electric CL 'the symmetrical transconductance amplifiers 104891 .doc 1281780 乂 Two are a unit 'for example symmetrical transconductance amplifier and 4 〇 2 for one unit. The two symmetrical transconductance amplifications in the unit are coupled to each other at the input end and the output end. The output capacitor C1 is coupled to the output of the unit. We can observe the characteristics of the circuit by looking up the conversion function (see r

Schaumann, and Μ. Ε. Van Valkenburg, design of Analog

Filters^ Published by Oxford tt · · ^ y xiord University Press, Inc? 2001·). On the vL node, the ancient a 1 text is used to see the Kirchhoffs rules for further analysis as follows: -sCLVL .gmdvi +gnid.y2 = ^ y = burning d (V2-V〇

sCL can be pushed 1丨 and 12 : , T — gm/dv,) cP 丄 2 -----,

SCT

CT, so the power can be obtained as shown in the right: l, refer to Figure 5, which shows the equivalent circuit schematic of the active resistor. The active resistor 50 includes a symmetrical transconductance amplifier, 5 〇: an input positive terminal coupled to the -output negative terminal, and its - input negative terminal coupled with positive:. We can also observe the characteristics of the circuit by looking up the conversion function of the circuit. The equivalent resistance ruler is ··· R==Z = —^—1 +蚬 1 gmd.V-^7. Therefore, 'the active inductance value and the active resistance value are determined by ah, the stability of the purchase & indirectly affects the active influence to the whole" (four) operational stability. Especially the wave (four) ^ value is built into Standing on the values of the active components, the stability of the active components dominates the characteristics of the entire filter. 104891.doc 1281780 Referring to Figure 6, there is shown a schematic diagram of an operational transconductance amplifier with tail current control of the present invention. The operational transconductance amplifier with tail current control of the present invention can be applied to the symmetric transduction amplifiers 401, 402, 403, 404, 50 of Fig. 4 or Fig. 5 described above. The operational transconductance amplifier 60 with tail current control of the present invention comprises: at least six inverters 61, 62, 63, 64, 65, 66 and at least six tail current transistors NM601, NM602, NM603, NM604, NM605, NM606 . The six inverters are respectively coupled to a first voltage input terminal VI+, a second voltage input terminal VI---the first voltage output terminal VOUT-, and a second voltage output terminal VOUT+. In detail, a first inverter 61 is coupled to the first voltage input terminal VI + and the first voltage output terminal VOUT. A second inverter 62 is coupled to the second voltage input terminal VI and the second voltage output terminal VOUT+. A third inverter 63 is coupled to the first voltage output terminal VOUT - and the second voltage output terminal VOUTT. A fourth inverter 64 is coupled to the second voltage output terminal VOUTE, and the input and output of the fourth inverter 64 are coupled together. A fifth inverter 65 is coupled to the first voltage output terminal VOUT - and the second voltage output terminal VOUTE. A sixth inverter 66 is coupled to the first voltage wheel terminal VOUT-, and the input and output of the sixth inverter 66 are coupled together. The six tail current transistors NM601, NM602, NM603, NM604, NM605, and NM606 are respectively coupled between the corresponding inverters and the ground. For example, the first tail current transistor NM60 1 is coupled between the first inverter 61 and the ground, the second tail current transistor NM602 is coupled between the second inverter 62 and the ground, and the third The tail current transistor NM603 is coupled to 104891.doc -10- 1281780. The third inverter 63 is connected to the ground, and the fourth tail current transistor is coupled to the fourth inverter 64 and the ground. The fifth and fourth tail current transistors NM605 are coupled to the fifth inverter "between the ground and the sixth tail current transistor NM606, and are connected between the sixth inverter 66 and the ground." - the tail current transistor is a transistor, and the gates of the N transistors are controlled by a reference voltage (vbias). In the transduction amplifier 60 of the present invention having tail current control, The φ inverter plus the tail current transistor is used to control the tail current, so that the bias current of the mouth-turning amplifier is limited, and is not affected by the drift of the temperature without a drastic effect. The transconductance amplifier stabilizes the gmd value by limiting the bias current by the current mirror. 3. In order to minimize the influence of the anti-aliasing filter of the present invention on the power supply voltage (VDD) drift, the voltage regulator 33 is added to the power supply portion to provide a stable 28 V power supply to the temperature compensation circuit. And the active inductor-capacitor step filter 3 i. Referring to Figure 7, there is shown a schematic diagram of the voltage regulator circuit of the present invention. The voltage regulator includes a cas code bandgap circuitry 701, An operation amplifier 702 and a set of series resistors R701 and R7 〇 2. The output voltage of the spliced band difference circuit 〇1 is connected to the series resistor R7〇1&R7 via the The stable power supply is provided after the partial pressure of 2. The spliced differential circuit 701 is implemented by the circuit shown in Fig. 8. The 5 hai tong differential circuit 70 1 generates a stable DC level of about 1.2. Volt' is then divided by the operational amplifier 7〇2 and the series resistor at 7〇1 and 7〇2 to output a stable voltage of 2·8 volts. 104891 .doc -11 - 1281780 Referring to Figure 9, the present invention is shown A schematic diagram of a temperature compensation circuit. The temperature compensation circuit 32 is provided The reference voltage (Vbias) to the active inductor-capacitor step filter, the filter 31' stabilizes the 3 dB bandwidth of the active inductor/capacitor step chopper 31. The temperature compensation circuit 32 includes a band difference circuit. a current mirror and a MOS DG-connected diode N3. The difference circuit is configured to generate a current through the current mirror. The current has a positive temperature coefficient characteristic, and the current flows into the MOS gate-connected diode NM9〇3. Moreover, the MOS 汲-gate connection diode nM903 has a negative temperature coefficient characteristic, and therefore, the voltage difference across the MOS 汲-gate connection diode has a temperature-insensitive characteristic, the voltage The difference is the reference voltage (Vb &). . The Vbias voltage is used to control the polarity of the tail current transistors in Figure 6. Utilizing the reference dust (Vbias), the bias current can be stabilized when the temperature drifts, so that the equivalent impedance of the active electrical phase of FIG. 4 and the active resistor 50 of FIG. 5 does not cause a sharp drift. Therefore, the bandwidth of the anti-depletion wave device 3G of the present invention can be effectively stabilized so that the 3 dB bandwidth of the anti-aliasing ripple of the present invention remains stable even at different operating temperatures. Referring to Figure iG, the simulation results of the anti-depletion wave device of the present invention are laid out under the process of 2 Ρ 4 Μ 35 um CM 〇s of Taiwan Integrated Circuits Corporation (TSMC), in the case of temperature drift, the cutoff When the frequency is 8·5ΜΗζ, the simulated process angle correction _er)' can be found that the highest frequency drift value is: 〇·264 MHz, so the maximum offset is ±〇264MHz/85Mh^士s η%, Yuan is smaller than the offset of the prior art. Figure 1 shows the post-layout simulation results for temperature drift, thunderback, and 调 秒 电 / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / However, the above embodiments are merely illustrative of the principles of the present invention and its advantages and advantages. Therefore, those skilled in the art can make modifications and changes to the above embodiments without departing from the spirit of the invention. The present invention is as set forth in the scope of the patent application described later. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a conventional sixth-order passive inductor-capacitor stepped filter; < 冤路不图2 is a circuit diagram of a conventional symmetric operational transconductance amplifier; FIG. 3 is a schematic diagram of the present invention; FIG. 4 is a schematic circuit diagram of a symmetric active inductor of the present invention; FIG. 5 is a schematic diagram of a circuit of an active resistor of the present invention, and FIG. 6 is an operation of the tail current control of the present invention. FIG. 7 is a schematic circuit diagram of a voltage regulator of the present invention; FIG. 8 is a schematic diagram of a circuit of the temperature compensation circuit of the present invention. FIG. ; ; and response map. Fig. 1 is F3dB=8.5 MHz, the simulation diagram of each corner Fig. 11 is Fwb U MHz, the frequency of each corner after layout [main component symbol description] 30 invention 31 active 32 temperature compensation 33 voltage regulator temperature compensation Anti-aliasing filter inductor-capacitor stepped filter compensation circuit 104891.doc 1281780 40 Symmetrical active inductor 50 Active resistor 60 Operational transconductance amplifier with tail current control

61 62 63 64 65 66 40 Bu 402 , 403 , 404 701 702 NM601 NM602 NM603 NM604 NM605 NM606 First Inverter Second Inverter Third Inverter Fourth Inverter Fifth Inverter Sixth Inverting Symmetrical transconductance amplifier stacked differential circuit operational amplifier first tail current transistor second tail current transistor third tail current transistor fourth tail current transistor fifth tail current transistor sixth tail current transistor 104891.doc -14-

Claims (1)

1281780 X. Patent Application Range·· h An operational transconductance amplifier with tail current control, comprising: · at least six inverters respectively coupled to a first voltage input terminal, a first voltage input terminal, and a first a voltage output end and a second voltage output end; and to >, a tail current transistor, respectively coupled to the corresponding inversion between the ground and the ground, each tail current electro-crystal system by a reference Voltage control. 2. The operational transconductance amplifier of the request, wherein a first inverter is coupled to the first voltage input terminal and the first voltage output terminal, and a second inverter is coupled to the second voltage input a second voltage output terminal, a first inverter coupled to the first voltage output terminal, and the second voltage output port and a fourth inverter coupled to the second voltage output terminal, A fifth inversion is coupled to the first voltage output and the second voltage output, and a sixth inverter is coupled to the first voltage output. 3. The operational transconductance amplifier of claim 1, wherein the tail current electro-emissive system is an N-type transistor, and the gates of the N-type transistors are controlled by the reference voltage. 4) A temperature compensated anti-aliasing filter, comprising: an active inductor-capacitor stepped filter comprising at least one symmetric active inductor, at least one capacitor and at least one active resistor, the active inductor-capacitor stepped The filter is used for filtering the input signal to remove the image frequency (Image Frequency); a temperature compensation circuit for providing a reference voltage to the active electric 104891.doc 1281780 sensing-electric valley stepping filter and wave filter to determine兮,, 3 the 3 dB bandwidth of the active inductor-capacitor step filter; a voltage regulator for providing a power supply to the dynamic inductor/capacitor step filter and the temperature Compensation circuit. 5. The anti-aliasing waver of claim 4, wherein the symmetric active inductor has at least four symmetric transconductance amplifiers and at least an output capacitor, and the symmetric transduction amplifiers are in two units, the unit The input end of the symmetrical transconductance amplifier is combined with the wheel end, and the output capacitor is coupled to the output end of the unit. 6. The anti-aliasing chopper of claim 4, wherein the active resistor comprises a symmetrical transconductance amplifier, the input positive terminal of the symmetrical transconductance amplifier is lightly coupled to: an output negative terminal 'and an input negative The end turns to an output positive end. 7' The anti-aliasing filter and wave device of claim 5 or 6, wherein the symmetric transduction amplifier comprises: at least six inverters respectively coupled to a first voltage wheel terminal and a second voltage input a human terminal, a first voltage output terminal and a second voltage output terminal; and at least six tail current transistors respectively coupled between the corresponding inverter and the ground terminal, each tail current electro-crystal system Controlled by this reference voltage. The anti-aliasing chopper of claim 7, wherein a first inverter is coupled to the first voltage input terminal and the first voltage output terminal, and a second inverter is coupled to the The second voltage input terminal and the second voltage output terminal are coupled to the first voltage output terminal and the second voltage output 104891.doc 1281780, and a fourth inverter is coupled To the second voltage output terminal, a fifth inverter is coupled to the first voltage output terminal and the second voltage output terminal, and a sixth inverter is coupled to the first voltage output terminal. The anti-aliasing filter of the month length item 7, wherein the tail current electro-crystal system is an N-type transistor, and the gates of the N-type transistors are controlled by the reference voltage. 1) The anti-aliasing filter of claim 4, wherein the temperature compensation circuit comprises a tributary circuit, a current mirror, and a MOS 汲-gate connected body (M〇S DG-connected diode The band difference circuit is configured to generate a current through the current mirror, and the current has a positive temperature coefficient (the σ 亥 〃 〃 IL system flows into the MOS 汲-gate connection diode, the M 〇 s - The gate connection diode has a negative temperature coefficient, so that the voltage difference across the junction of the 〇 〇 8 汲 具有 has a temperature-insensitive characteristic, and the voltage difference is the reference voltage. The anti-aliasing filter of item 4, wherein the voltage regulator comprises an operational amplifier, a stacked band difference circuit (casc〇de bandgap circuitry) and a set of series resistors, the stacked differential band circuit The output voltage is divided by the alien amplifier and the series resistor to provide the stable power supply. 104891.doc