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CN-121547027-B - Continuous time current comparator capable of outputting maximum and minimum currents

CN121547027BCN 121547027 BCN121547027 BCN 121547027BCN-121547027-B

Abstract

The invention discloses a continuous time current comparator capable of outputting maximum and minimum currents, which comprises 8 groups of common-source common-gate current mirrors consisting of NMOS (N1-N20) tubes and PMOS (P1-P8), wherein the drain electrode of the PMOS tube P2 is simultaneously connected with the drain electrode of an NMOS tube N5 and the drain electrode of an NMOS tube N7, the drain electrode of the PMOS tube P6 is simultaneously connected with the drain electrode of an NMOS tube N11 and the drain electrode of an NMOS tube N13, the drain electrode of the PMOS tube P8 is connected with the drain electrode of an NMOS tube N17, the current Ia to be compared is input from the drain electrode of an NMOS tube N1, the current Ib to be compared is divided into two paths to flow to the drain electrode of an NMOS tube N3 and the drain electrode of an NMOS tube N9 respectively, the drain electrode of an NMOS tube N19 outputs a maximum current Imax, and the drain electrode of an NMOS tube N15 outputs a minimum current Imin. After the currents Ia and Ib are compared, the maximum current Imax and the minimum current Imin corresponding to the currents Ia and Ib are output through current replication, summation and difference operation of the cascode current mirror, and the maximum current Imax and the minimum current Imin are continuous analog current signals.

Inventors

  • LI HAIRONG
  • LI YONGCHAO
  • LI BAOYU
  • LIU WEINING

Assignees

  • 兰州大学

Dates

Publication Date
20260508
Application Date
20251127

Claims (10)

  1. 1. A continuous time current comparator capable of outputting maximum and minimum currents, comprising 8 groups of cascode current mirrors; Wherein NMOS transistors N1, N2, N3 and N4 form a first group of cascode current mirrors, NMOS transistors N1, N2, N5 and N6 form a second group of cascode current mirrors, NMOS transistors N7, N8, N9 and N10 form a third group of cascode current mirrors, NMOS transistors N9, N10, N11 and N12 form a fourth group of cascode current mirrors, NMOS transistors N13, N14, N15 and N16 form a fifth group of cascode current mirrors, NMOS transistors N17, N18, N19 and N20 form a sixth group of cascode current mirrors, The PMOS tubes P1, P2, P7 and P8 form a seventh group of cascode current mirrors, PMOS tubes P3, P4, P5 and P6 form an eighth group of cascode current mirrors; The drain electrode of the PMOS tube P2 is simultaneously connected with the drain electrode of the NMOS tube N5 and the drain electrode of the NMOS tube N7, and the drain electrode of the NMOS tube N5 is connected with the drain electrode of the NMOS tube N7, the drain electrode of the PMOS tube P6 is simultaneously connected with the drain electrode of the NMOS tube N11 and the drain electrode of the NMOS tube N13, and the drain electrode of the NMOS tube N11 is connected with the drain electrode of the NMOS tube N13; The current Ia to be compared is input from the drain electrode of the NMOS tube N1, and the current Ib to be compared is divided into two paths after being input and flows to the drain electrode of the NMOS tube N3 and the drain electrode of the NMOS tube N9 respectively; The drain electrode of the NMOS transistor N19 outputs a maximum current Imax, and the drain electrode of the NMOS transistor N15 outputs a minimum current Imin, which are continuous analog current signals.
  2. 2. The continuous-time current comparator of claim 1, wherein the gate of the NMOS transistor N1 in the first set of cascode current mirrors is connected to the gate of the NMOS transistor N3, the gate of the NMOS transistor N2 is connected to the gate of the NMOS transistor N4, the source of the NMOS transistor N1 is connected to the drain of the NMOS transistor N2, the source of the NMOS transistor N3 is connected to the drain of the NMOS transistor N4, the source of the NMOS transistor N2 and the source of the NMOS transistor N4 are grounded, and the gates and the drains of the NMOS transistors N1 and N2 are shorted.
  3. 3. The continuous-time current comparator of claim 2, wherein the gate of NMOS transistor N5 in the second set of cascode current mirrors is connected to the gate of NMOS transistor N1, the gate of NMOS transistor N6 is connected to the gate of NMOS transistor N2, the source of NMOS transistor N5 is connected to the drain of NMOS transistor N6, and the source of NMOS transistor N6 is grounded.
  4. 4. The continuous-time current comparator of claim 1, wherein the gate of the NMOS transistor N7 in the third set of cascode current mirrors is connected to the gate of the NMOS transistor N9, the gate of the NMOS transistor N8 is connected to the gate of the NMOS transistor N10, the source of the NMOS transistor N7 is connected to the drain of the NMOS transistor N8, the source of the NMOS transistor N9 is connected to the drain of the NMOS transistor N10, the source of the NMOS transistor N8 and the source of the NMOS transistor N10 are grounded, and the gates and the drains of the NMOS transistor N9 and the NMOS transistor N10 are shorted.
  5. 5. The continuous-time current comparator according to claim 4, wherein the gate of the NMOS transistor N11 in the fourth set of cascode current mirrors is connected to the gate of the NMOS transistor N9, the gate of the NMOS transistor N12 is connected to the gate of the NMOS transistor N10, the source of the NMOS transistor N11 is connected to the drain of the NMOS transistor N12, and the source of the NMOS transistor N12 is grounded.
  6. 6. The continuous-time current comparator according to claim 1, wherein the gate of the NMOS transistor N13 in the fifth group of cascode current mirrors is connected to the gate of the NMOS transistor N15, the gate of the NMOS transistor N14 is connected to the gate of the NMOS transistor N16, the source of the NMOS transistor N13 is connected to the drain of the NMOS transistor N14, the source of the NMOS transistor N15 is connected to the drain of the NMOS transistor N16, the source of the NMOS transistor N14 and the source of the NMOS transistor N16 are both grounded, and the gates and the drains of the NMOS transistor N13 and the NMOS transistor N14 are both shorted.
  7. 7. The continuous-time current comparator of claim 1, wherein the gate of NMOS transistor N17 in the sixth set of cascode current mirrors is connected to the gate of NMOS transistor N19, the gate of NMOS transistor N18 is connected to the gate of NMOS transistor N20, the source of NMOS transistor N17 is connected to the drain of NMOS transistor N18, the source of NMOS transistor N19 is connected to the drain of NMOS transistor N20, the source of NMOS transistor N18 and the source of NMOS transistor N20 are both grounded, and the gates and drains of NMOS transistor N17 and NMOS transistor N18 are shorted.
  8. 8. The continuous-time current comparator of claim 1, wherein the gate of the PMOS tube P1 in the seventh group of common-source common-gate current mirrors is connected with the gate of the PMOS tube P7, the gate of the PMOS tube P2 is connected with the gate of the PMOS tube P8, the sources of the PMOS tube P1 and the PMOS tube P7 are both connected with the power supply, the drain of the PMOS tube P1 is connected with the source of the PMOS tube P2, the drain of the PMOS tube P7 is connected with the source of the PMOS tube P8, and the gates and the drains of the PMOS tube P1 and the PMOS tube P2 are both short-circuited.
  9. 9. The continuous-time current comparator of claim 1, wherein the gate of the PMOS tube P3 in the eighth group of common-source common-gate current mirrors is connected with the gate of the PMOS tube P5, the gate of the PMOS tube P4 is connected with the gate of the PMOS tube P6, the sources of the PMOS tube P3 and the PMOS tube P5 are connected with the power supply, the drain of the PMOS tube P3 is connected with the source of the PMOS tube P4, the drain of the PMOS tube P5 is connected with the source of the PMOS tube P6, and the gates and the drains of the PMOS tube P3 and the PMOS tube P4 are short-circuited.
  10. 10. The continuous-time current comparator according to claim 1, wherein the continuous-time current comparator is a continuous-time current comparator having a rise time of less than 15ns, a transmission error of less than 2nA, and an input offset current of 4nA or less, and the rise time is a time required for a current signal to rise from 10% to 90% of an amplitude.

Description

Continuous time current comparator capable of outputting maximum and minimum currents Technical Field The invention relates to the field of circuits, in particular to a continuous time current comparator capable of outputting maximum and minimum currents. Background CMOS current comparators have been developed over the years, with the simplest method comprising a current mirror comparator circuit as shown in fig. 1, where P1-P4 and N1-N4 each form a cascode current mirror and P5 and N5 form a primary inverter. The core function is to compare two input currents Iin1 and Iin2 and output a digital signal (high level or low level). The operation is that the P4 transistor 1:1 is assumed to replicate the current of P3, i.e. I_P4 apprxeq Iin1, and the N2 transistor 1:1 replicates the current of N1, i.e. I_N2 apprxeq Iin2. If I_P4 > I_N2, P4 provides a current greater than the current absorbed by N2, the Vx node has an electrostatic current injected, the voltage is pulled high (near VDD), and after passing through the primary inverter, the output Vout is low. If I_P4 < I_N2, N2 absorbs more current than P4, the Vx node has static current flowing out, the voltage is pulled low (near VSS), after passing through the primary inverter, the output Vout is high. The circuit has simple structure and easy realization, and due to the adoption of the cascode current mirror, the replica current is accurate, but the circuit has some defects that firstly, the circuit outputs a digital signal at last, the circuit is not applicable to some analog signal processing systems (for example, the maximum or minimum of input currents is the result of outputting), in addition, an inverter can introduce extra propagation delay, the comparison speed is influenced, and the response speed of the circuit is reduced. In addition, the indirect comparison method based on the voltage comparator in other implementation methods is low in speed, and requires accurate resistor and high-performance voltage comparator, so that power consumption and chip area can be increased, and the high-speed latch type current comparator applied at high speed is driven in a time sequence and cannot continuously output. Disclosure of Invention The invention aims to provide a continuous-time current comparator which does not need current-voltage conversion and can directly and accurately output maximum and minimum currents. The invention provides a continuous time current comparator capable of outputting maximum and minimum currents, which comprises 8 groups of cascode current mirrors; Wherein NMOS transistors N1, N2, N3 and N4 form a first group of cascode current mirrors, NMOS transistors N1, N2, N5 and N6 form a second group of cascode current mirrors, NMOS transistors N7, N8, N9 and N10 form a third group of cascode current mirrors, NMOS transistors N9, N10, N11 and N12 form a fourth group of cascode current mirrors, NMOS transistors N13, N14, N15 and N16 form a fifth group of cascode current mirrors, NMOS transistors N17, N18, N19 and N20 form a sixth group of cascode current mirrors, The PMOS tubes P1, P2, P7 and P8 form a seventh group of cascode current mirrors, PMOS tubes P3, P4, P5 and P6 form an eighth group of cascode current mirrors; The drain electrode of the PMOS tube P2 is simultaneously connected with the drain electrode of the NMOS tube N5 and the drain electrode of the NMOS tube N7, and the drain electrode of the NMOS tube N5 is connected with the drain electrode of the NMOS tube N7, the drain electrode of the PMOS tube P6 is simultaneously connected with the drain electrode of the NMOS tube N11 and the drain electrode of the NMOS tube N13, and the drain electrode of the NMOS tube N11 is connected with the drain electrode of the NMOS tube N13; The current Ia to be compared is input from the drain electrode of the NMOS tube N1, and the current Ib to be compared is divided into two paths after being input and flows to the drain electrode of the NMOS tube N3 and the drain electrode of the NMOS tube N9 respectively; The drain electrode of the NMOS transistor N19 outputs a maximum current Imax, and the drain electrode of the NMOS transistor N15 outputs a minimum current Imin, which are continuous analog current signals. Further, according to the continuous time current comparator disclosed by the invention, the grid electrode of the NMOS tube N1 in the first group of the common-source common-gate current mirrors is connected with the grid electrode of the NMOS tube N3, the grid electrode of the NMOS tube N2 is connected with the grid electrode of the NMOS tube N4, the source electrode of the NMOS tube N1 is connected with the drain electrode of the NMOS tube N2, the source electrode of the NMOS tube N3 is connected with the drain electrode of the NMOS tube N4, the source electrodes of the NMOS tube N2 and the NMOS tube N4 are grounded, and the grid electrodes and the drain electrodes of the NMOS tube N1 and the NMOS tube N2 are short-circuited. Further, ac