Filter with process corner temperature compensation

Abstract

The invention discloses a filter with process angle temperature compensation, which comprises a fully differential operational amplifier, a first resistor matrix, a second resistor matrix, a third resistor matrix, a fourth resistor matrix, a fifth resistor matrix, a sixth resistor matrix, a first capacitor, a second capacitor and a third capacitor, the second end of the first resistor matrix is connected with the first end of the third resistor matrix, the first end of the third capacitor and the first end of the fifth resistor matrix, the first end of the second resistor matrix is connected with the negative differential input end, and the second end of the second resistor matrix is connected with the first end of the fourth resistor matrix, the second end of the third capacitor and the first end of the sixth resistor matrix. The second end of the third resistor matrix is connected with the positive input end of the amplifier and the first end of the first capacitor, the second end of the fourth resistor matrix is connected with the negative input end of the amplifier and the first end of the second capacitor, and the second end of the fifth resistor matrix is connected with the second end of the first capacitor and the negative output end of the amplifier. The second end of the sixth resistor matrix is connected with the second end of the second capacitor and the positive output end of the amplifier. According to the invention, good filtering characteristics can be realized.

Description

Technical Field

[0001] The invention belongs to the field of active RC filters, and in particular relates to a filter with process angle temperature compensation. Background Art

[0002] In an adjustable active RC filter, the bandwidth is determined by capacitance and resistance. In silicon-based processes, resistance changes significantly with temperature. At different temperatures, the resistance value differs by 20%. At the same time, during the tape-out process, the resistance value caused by different process angles differs by 40%. The deviation of the resistance value causes the bandwidth deviation of the existing filter at different process angle temperatures to double. In particular, the bandwidth drift of the multi-stage filter makes the filtering characteristics of the filter much worse. Summary of the invention

[0003] The object of the present invention is to provide a filter with process angle temperature compensation, which can achieve relatively constant bandwidth of the filter at different process angle temperatures and achieve good filtering characteristics.

[0004] One aspect of the present invention provides a filter with process angle temperature compensation, comprising a fully differential operational amplifier, a first resistor matrix to a sixth resistor matrix, a first capacitor to a third capacitor, a positive differential input terminal, a negative differential input terminal, a positive differential output terminal and a negative differential output terminal. Among them, the first end of the first resistor matrix is ​​connected to the positive differential input terminal, the second end of the first resistor matrix is ​​connected to the first end of the third resistor matrix, the first end of the third capacitor, and the first end of the fifth resistor matrix, the first end of the second resistor matrix is ​​connected to the negative differential input terminal, the second end of the second resistor matrix is ​​connected to the first end of the fourth resistor matrix, the second end of the third capacitor, and the first end of the sixth resistor matrix, the second end of the third resistor matrix is ​​connected to the positive input terminal of the fully differential operational amplifier and the first end of the first capacitor, the second end of the fourth resistor matrix is ​​connected to the negative input terminal of the fully differential operational amplifier and the first end of the second capacitor, the second end of the fifth resistor matrix is ​​connected to the second end of the first capacitor, the negative output terminal of the fully differential operational amplifier, and the negative differential output terminal, and the second end of the sixth resistor matrix is ​​connected to the second end of the second capacitor, the positive output terminal of the fully differential operational amplifier, and the positive differential output terminal.

[0005] Preferably, the first resistor matrix to the sixth resistor matrix have the same resistor matrix structure, including 9 temperature compensation resistor pairs in parallel and 9 switches connected in series with the 9 temperature compensation resistor pairs respectively, each temperature compensation resistor pair is composed of two resistors with opposite temperature coefficients, and the resistance value of the resistor matrix structure can be changed by selectively conducting the 9-way switch to compensate for the resistance value deviation at different process angle temperatures.

[0006] Preferably, the 9-way switches are the first switch to the ninth switch, wherein the first switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is R; the second switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 19 / 20R; the third switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 18 / 20R; the fourth switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 17 / 20R; the fifth switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 16 / 20R; the sixth switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 15 / 20R; the seventh switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 14 / 20R; the eighth switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 13 / 20R; the ninth switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 12 / 20R, wherein R is the maximum resistance of the temperature compensation resistor pair.

[0007] According to the filter with process angle temperature compensation according to the above aspect of the present invention, it is possible to achieve a relatively constant bandwidth of the filter at different process angle temperatures, thereby achieving good filtering characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work: Figure 1 is a schematic diagram of a filter with process angle temperature compensation according to an embodiment of the present invention; Figure 2 It is a schematic diagram of a resistor matrix according to one embodiment of the present invention. DETAILED DESCRIPTION

[0009] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0010] The embodiment of the present invention provides a filter with process angle temperature compensation, such as Figure 1 As shown, the filter with process angle temperature compensation according to the embodiment of the present invention includes a fully differential operational amplifier FDA, 6 resistor matrices with the same structure (the first resistor matrix R matrix1 ~Sixth resistor matrix Rmatrix6 ), 3 capacitors (first capacitor C1 to third capacitor C3), positive differential input terminal Vin+, negative differential input terminal Vin-, positive differential output terminal Vout+ and negative differential output terminal Vout-.

[0011] The first resistor matrix R matrix1 The first end of the first resistor matrix R is connected to the positive differential input terminal Vin+. matrix1 The second end and the third resistor matrix R matrix3 The first end of the third capacitor C3, the first end of the fifth resistor matrix R matrix5 The first end of the second resistor matrix R matrix2 The first end of the resistor matrix R matrix2 The second end of the fourth resistor matrix R matrix4 The first end of the third capacitor C3, the second end of the sixth resistor matrix R matrix6 The first end of the third resistor matrix R matrix3 The second end of the fourth resistor matrix R is connected to the positive input end of the full differential operational amplifier FDA and the first end of the first capacitor C1. matrix4 The second end of the fifth resistor matrix R is connected to the negative input terminal of the full differential operational amplifier FDA and the first end of the second capacitor C2. matrix5 The second end of the sixth resistor matrix R is connected to the second end of the first capacitor C1, the negative output end of the fully differential operational amplifier FDA, and the negative differential output end Vout-. matrix6 The second end of is connected to the second end of the second capacitor C2, the positive output end of the fully differential operational amplifier FDA, and the positive differential output end Vout+.

[0012] The first resistor matrix R matrix1 ~Sixth resistor matrix R matrix6 Together with the first capacitor C1 to the third capacitor C3, an RC network is formed. The value of the RC network determines the cutoff frequency, which is used to achieve different attenuation or enhancement effects on signals of different frequencies, that is, to achieve a filtering effect.

[0013] The first resistor matrix R matrix1 ~Sixth resistor matrix R matrix6 The resistor matrix structure is referred to as the resistor matrix R matrix .like Figure 2 As shown, the resistance matrix R matrixIt includes 9 temperature compensation resistor pairs connected in parallel and 9 switches connected in series with the 9 temperature compensation resistor pairs respectively. The compensation resistor pairs (R0, R1), (R2, R3), (R4, R5), ... (R18, R19) are composed of resistors with opposite temperature coefficients. R0, R2, R4, ... R18 are resistors with positive temperature coefficients, and R1, R3, R5, ... R19 are resistors with negative temperature coefficients. The resistor pairs with two temperature coefficients are used to achieve constant resistance values ​​at different temperatures. The resistance value of the positive temperature coefficient increases with the increase of temperature, and the resistance value of the negative temperature coefficient decreases with the increase of temperature. By connecting the two resistors in series, the resistance value change of the resistor value at different temperatures can be eliminated, and the resistance value can be constant.

[0014] In this embodiment, 9 pairs of temperature compensation resistors are used to form a resistance matrix R matrix , bandwidth deviation ≤ 5% can be achieved, but the resistor matrix R matrix The number of resistor pairs can be larger to achieve a smaller bandwidth shift, but the chip area will be larger.

[0015] The 9-way switch is used to select conduction to change the resistance matrix R matrix The resistance value can compensate for the resistance deviation under different process angles. Assuming R is the maximum resistance of the temperature compensation resistor pair (R0, R1), (R2, R3), (R4, R5), ... (R18, R19), then: Switch S0 (first switch) is open, switches S1, S2, S3, S4, S5, S6, S7, S8, and S9 are closed, and the resistance value R is selected.

[0016] Switch S1 (second switch) is open, switches S0, S2, S3, S4, S5, S6, S7, S8, and S9 are closed, and the selected resistance value is 19 / 20R.

[0017] Switch S2 (the third switch) is open, switches S0, S1, S3, S4, S5, S6, S7, S8, and S9 are closed, and the selected resistance value is 18 / 20R.

[0018] Switch S3 (the fourth switch) is turned on, switches S0, S1, S2, S4, S5, S6, S7, S8, and S9 are turned off, and the selected resistance value is 17 / 20R.

[0019] Switch S4 (fifth switch) is open, switches S0, S1, S2, S3, S5, S6, S7, S8, and S9 are closed, and the selected resistance value is 16 / 20R.

[0020] Switch S5 (the sixth switch) is turned on, switches S0, S1, S2, S3, S4, S6, S7, S8, and S9 are turned off, and the selected resistance value is 15 / 20R.

[0021] Switch S6 (the seventh switch) is turned on, switches S0, S1, S2, S3, S4, S5, S7, S8, and S9 are turned off, and the selected resistance value is 14 / 20R.

[0022] Switch S7 (the eighth switch) is turned on, switches S0, S1, S2, S3, S4, S5, S6, S8, and S9 are turned off, and the selected resistance value is 13 / 20R.

[0023] Switch S8 (the ninth switch) is turned on, switches S0, S1, S2, S3, S4, S5, S6, S7, and S9 are turned off, and the selected resistance value is 12 / 20R.

[0024] The filter of the above embodiment of the present invention adopts the process angle temperature compensation technology, and realizes the relatively constant bandwidth of the filter at different process angle temperatures through the resistor matrix, with a deviation rate of ≤5%, and has good filtering characteristics. Specifically, compared with the traditional RC filter, the filter of the above-mentioned embodiment of the present invention compensates for the resistance change of the resistance value at different temperatures through two resistor pairs with opposite temperature coefficients. At the same time, due to the process deviations existing in the manufacturing process of semiconductor devices, these deviations include inconsistencies in doping concentration, diffusion depth, and etching degree, resulting in inconsistent drift speeds of carriers in the chip manufacturing process, thereby causing deviations in the resistance value, and the deviation rate reaches 40%. That is, in the manufacturing process of the same batch of chips, for example, a resistor with a resistance value of 1KΩ under a normal temperature tt process angle has a resistance range of 0.8KΩ~1.2KΩ. By selecting 9 pairs of switch resistor matrices, a resistance selection of 0.75KΩ~1.25KΩ can be achieved, and the adjustment step is 1 / 20 R, that is, a resistance value deviation rate of ≤5% can be achieved, so that the filter achieves good filtering characteristics.

[0025] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A filter with process angle temperature compensation, characterized in that: The invention comprises a fully differential operational amplifier, a first resistor matrix to a sixth resistor matrix, a first capacitor to a third capacitor, a positive differential input terminal, a negative differential input terminal, a positive differential output terminal and a negative differential output terminal. Among them, the first end of the first resistor matrix is ​​connected to the positive differential input terminal, the second end of the first resistor matrix is ​​connected to the first end of the third resistor matrix, the first end of the third capacitor, and the first end of the fifth resistor matrix, the first end of the second resistor matrix is ​​connected to the negative differential input terminal, the second end of the second resistor matrix is ​​connected to the first end of the fourth resistor matrix, the second end of the third capacitor, and the first end of the sixth resistor matrix, the second end of the third resistor matrix is ​​connected to the positive input terminal of the fully differential operational amplifier and the first end of the first capacitor, the second end of the fourth resistor matrix is ​​connected to the negative input terminal of the fully differential operational amplifier and the first end of the second capacitor, the second end of the fifth resistor matrix is ​​connected to the second end of the first capacitor, the negative output terminal of the fully differential operational amplifier, and the negative differential output terminal, and the second end of the sixth resistor matrix is ​​connected to the second end of the second capacitor, the positive output terminal of the fully differential operational amplifier, and the positive differential output terminal.

2. The filter with process angle temperature compensation as claimed in claim 1, characterized in that: The first resistor matrix to the sixth resistor matrix have the same resistor matrix structure, including 9 temperature compensation resistor pairs connected in parallel and 9 switches connected in series with the 9 temperature compensation resistor pairs respectively. Each temperature compensation resistor pair is composed of two resistors with opposite temperature coefficients. The resistance value of the resistor matrix structure can be changed by selectively conducting the 9-way switch to compensate for the resistance value deviation at different process angle temperatures.

3. The filter with process angle temperature compensation as claimed in claim 2, characterized in that: The 9-way switches are the first switch to the ninth switch, wherein the first switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is R; the second switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 19 / 20R; the third switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 18 / 20R; the fourth switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 17 / 20R; the fifth switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 16 / 20R; the sixth switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 15 / 20R; the seventh switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 14 / 20R; the eighth switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 13 / 20R; the ninth switch is turned on, the other switches are turned off, and the resistance value of the resistor matrix structure is 12 / 20R, wherein R is the maximum resistance of the compensation resistor pair.

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