A current-frequency conversion hybrid integrated circuit

Abstract

The present invention discloses a current-frequency conversion hybrid integrated circuit, comprising a constant current source, a switch module, a clock module, and a positive and negative current processing module, an integrator, a first comparator, and a logic control module connected in series in sequence; the positive and negative current processing module is used to obtain the input positive and negative currents and output them in a differentiated manner; the integrator is used to obtain the output signals of the positive and negative current processing modules and perform integration processing; the first comparator is used to obtain the output signals of the integrator and compare them with the threshold voltage; the logic control module is used to obtain the output signals of the first comparator and the clock module and generate a frequency pulse signal; the constant current source is connected to the integrator input terminal through the switch module contact terminal to provide a reset current for the integrator, and the switch module control terminal is connected to the logic control module output terminal; the present invention has the advantages of symmetrical positive and negative output frequencies, simple structure, and low cost.

Description

Technical Field

[0001] The invention relates to a current-frequency conversion hybrid integrated circuit, belonging to the technical field of signal processing. Background Art

[0002] The current-to-frequency converter circuit is an analog-to-digital converter based on the charge balance principle. It converts an analog current input signal into a count pulse signal, where the frequency of the count pulse is proportional to the magnitude of the input current signal. It offers advantages such as small size, high precision, low cost, and good linearity. It is widely used in navigation, radar, remote control and telemetry, data acquisition, and communication systems.

[0003] Patent No. CN202853621U discloses a current-frequency conversion circuit, such as Figure 1 As shown, the device includes components such as an integrator, a comparator, a digital logic circuit, and an electronic switch. The comparator's input is connected to the integrator's output, the comparator's output is connected to the digital logic circuit's input, and the digital logic circuit's output is connected to the output circuit. The digital logic circuit's output is also connected to the integrator's input via an electronic switch, forming a functional circuit comprising an integrator, two positive and negative channels, a positive and negative constant current source, and an electronic switch. When a positive current is input, the positive channel and the negative constant current operate, and a pulse signal is output at the FO+ terminal. When a negative current is input, the negative channel and the positive constant current operate, and a pulse signal is output at the FO- terminal. The device suffers from poor symmetry in the positive and negative output frequencies, requiring adjustment of the positive and negative constant current sources to meet practical requirements. Furthermore, the device is complex and expensive. Summary of the Invention

[0004] The object of the present invention is to overcome the deficiencies in the prior art and to provide a current-frequency conversion hybrid integrated circuit having the advantages of symmetrical positive and negative output frequencies, simple structure and low cost.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0006] The present invention provides a current-frequency conversion hybrid integrated circuit, comprising a constant current source, a switch module, a clock module, and a positive and negative current processing module, an integrator, a first comparator, and a logic control module connected in series in sequence; the positive and negative current processing module is used to obtain the input positive and negative currents and output them in a differentiated manner; the integrator is used to obtain the output signals of the positive and negative current processing modules and perform integration processing; the first comparator is used to obtain the output signals of the integrator and compare them with a threshold voltage; the logic control module is used to obtain the output signals of the first comparator and the clock module and generate a frequency pulse signal; the constant current source is connected to the integrator input terminal through the switch module contact terminal to provide a reset current for the integrator, and the switch module control terminal is connected to the logic control module output terminal.

[0007] Optionally, the positive and negative current processing module includes a first sampling resistor, an operational amplifier, a first electronic switch, a second electronic switch, a second comparator and a third comparator; the first sampling resistor serves as the input end of the positive and negative current processing module, one end of the first sampling resistor is grounded, two ends of the first sampling resistor are respectively connected to the input end of the operational amplifier and one end of the second electronic switch contact, the output end of the operational amplifier is connected to one end of the first electronic switch contact, the two ends of the first electronic switch and the second electronic switch contact are connected to form an output common end and serve as the output end of the positive and negative current processing module; the positive input end of the second comparator is connected to the two ends of the first sampling resistor, the output end of the second comparator is respectively connected to the first electronic switch control end and the negative input end of the third comparator, and the output end of the third comparator is connected to the second electronic switch control end; the negative input end of the second comparator and the positive input end of the third comparator are both grounded.

[0008] Optionally, the logic control module includes a digital logic circuit, a first logic operation circuit and a second logic operation circuit; the input end of the digital logic circuit is respectively connected to the clock module and the output end of the first comparator, and the output end of the digital logic circuit is respectively connected to the input end of the first logic operation circuit and the second logic operation circuit, and the input end of the first logic operation circuit and the second logic operation circuit are also respectively connected to the control end of the second comparator and the third comparator, and the output end of the first logic operation circuit and the second logic operation circuit serve as the output end of the logic control module.

[0009] Optionally, the switch module includes a third electronic switch and a fourth electronic switch, the control ends of the third electronic switch and the fourth electronic switch are respectively connected to the output ends of the first logic operation circuit and the second logic operation circuit, one end of the contact of the third electronic switch and the fourth electronic switch are connected to form a common contact end, two ends of the contact of the third electronic switch and the fourth electronic switch are connected to form two common contact ends, the common contact end is connected to the integrator input end, and the two common contact ends are connected to the constant current source output end.

[0010] Optionally, the constant current source includes a voltage reference source, a voltage follower, and a second sampling resistor connected in series.

[0011] Optionally, the integrator includes a capacitor and a comparator, and the capacitor is connected between the output terminal and the inverting input terminal of the comparator.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] The present invention provides a current-frequency conversion circuit. By connecting a positive and negative current processing module, an integrator, a first comparator and a logic control module in series, the circuit shares the same integrator, the same comparator, the same logic control module and the same constant current source when operating with positive and negative currents input respectively. This significantly improves the symmetry of the positive and negative output frequencies and the linearity of the circuit output frequency. The circuit also has the advantages of small size, strong versatility, simple structure and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of a current-frequency conversion circuit provided in the background technology of the present invention;

[0015] Figure 2 This is a schematic diagram of a current-frequency conversion hybrid integrated circuit provided by the first embodiment of the present invention;

[0016] Figure 3 is a schematic diagram of a positive and negative current processing module provided in Example 1 of the present invention;

[0017] Figure 4 This is a schematic diagram of a positive and negative current processing module provided in the first embodiment of the present invention;

[0018] Figure 5 is a schematic diagram of an integrator and a first comparator provided in the first embodiment of the present invention;

[0019] Figure 6 is a schematic diagram of a logic control module and a switch module provided in Example 1 of the present invention;

[0020] Figure 7 This is a schematic diagram of a logic control module and a switch module provided in the first embodiment of the present invention;

[0021] Figure 8 Schematic diagram of a constant current source provided in Example 1 of the present invention;

[0022] Figure 9 This is a schematic diagram of a constant current source provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0024] Example 1:

[0025] like Figure 2As shown, the present invention provides a current-frequency conversion hybrid integrated circuit, including a constant current source, a switch module, a clock module, and a positive and negative current processing module, an integrator, a first comparator and a logic control module connected in series in sequence; the positive and negative current processing module is used to obtain the positive and negative currents of the input and output them in a differentiated manner; the integrator is used to obtain the output signals of the positive and negative current processing modules and perform integration processing; the first comparator is used to obtain the output signal of the integrator and compare it with the threshold voltage; the logic control module is used to obtain the output signals of the first comparator and the clock module and generate a frequency pulse signal; the constant current source is connected to the integrator input terminal through the switch module contact terminal to provide a reset current for the integrator, and the switch module control terminal is connected to the logic control module output terminal.

[0026] like Figure 3 As shown, the positive and negative current processing module includes a first sampling resistor, an operational amplifier, a first electronic switch, a second electronic switch, a second comparator and a third comparator; the first sampling resistor serves as the input end of the positive and negative current processing module, one end of the first sampling resistor is grounded, two ends of the first sampling resistor are respectively connected to the input end of the operational amplifier and one end of the contact of the second electronic switch, the output end of the operational amplifier is connected to one end of the contact of the first electronic switch, two ends of the first electronic switch and the second electronic switch contact are connected to form an output common end and serve as the output end of the positive and negative current processing module; the positive input end of the second comparator is connected to the two ends of the first sampling resistor, the output end of the second comparator is respectively connected to the control end of the first electronic switch and the negative input end of the third comparator, and the output end of the third comparator is connected to the control end of the second electronic switch; the negative input end of the second comparator and the positive input end of the third comparator are both grounded.

[0027] When the input of the positive and negative current processing module is positive current, the second comparator outputs a high level and the third comparator outputs a low level. At this time, the first electronic switch is turned on and the second electronic switch is turned off. The input positive current charges the integrator through the operational amplifier and the first electronic switch.

[0028] When the input of the positive and negative current processing module is negative current, the second comparator outputs a low level and the third comparator outputs a high level. At this time, the second electronic switch is turned on and the first electronic switch is turned off. The input negative current charges the integrator through the second electronic switch.

[0029] like Figure 4As shown, this embodiment provides a schematic diagram of a positive and negative current processing module, wherein the first sampling resistor, the operational amplifier, the first electronic switch, the second electronic switch, the second comparator, and the third comparator are respectively denoted as resistor R1, comparator U1, MOS transistor Q1, MOS transistor Q2, comparator U2, and comparator U3; one end of the resistor R1 is grounded, and the other end is connected to the common end of the resistor R2, the resistor R5, and the resistor R21; the other end of the resistor R2 is connected to the inverting input end of the comparator U1; the non-inverting input end of the comparator U1 is grounded; the resistor R3 is connected between the inverting input end and the output end of the comparator U1; the positive power supply end of the comparator U1 is connected to the +15V power supply, and the negative power supply end is connected to the -15V power supply; one end of the resistor R4 is connected to the output end of the comparator U1, and the other end is connected to the positive power supply end of the MOS transistor Q1. The drain terminal of the integrator is connected to the drain of MOS transistor Q2. The sources of MOS transistors Q1 and Q2 are connected together to the inverting input of the integrator. The other end of resistor R21 is connected to the non-inverting input of comparator U2. The inverting input of comparator U2 is grounded. The positive power supply of comparator U2 is connected to the +15V power supply, and the negative power supply is connected to the -15V power supply. The output terminal is connected to the common terminal of resistors R6 and R18. The other end of resistor R6 is connected to the gate of MOS transistor Q1. Resistor R18 is connected to the inverting input of comparator U3. The non-inverting input of comparator U3 is grounded. The positive power supply of comparator U3 is connected to the +15V power supply, and the negative power supply is connected to the -15V power supply. The output terminal is connected to the gate of MOS transistor Q2 through resistor R19 and to ground through resistor R20. The cathode of diode D3 is connected to the common terminal of resistor R6 and the gate of MOS transistor Q1. The positive electrode is connected to the anode of diode D4. The cathode of diode D4 is grounded.

[0030] Among them, the resistor R3 is connected to the inverting input terminal and the output terminal of the comparator U1, forming a negative feedback loop of the comparator U1, so that the comparator U1 functions as an operational amplifier. The MOS transistors Q1 and Q2 have a low threshold voltage and an extremely fast response speed, and function as switches. The diodes D3 and D4 are connected in reverse series to provide overvoltage protection for the circuit.

[0031] Comparators U2 and U3 control the on and off states of MOS tubes Q1 and Q2. When the input is a positive current, comparator U2 outputs a high level and comparator U3 outputs a low level. At this time, MOS tube Q1 is turned on and MOS tube Q2 is turned off. The input positive current is converted into a negative current by comparator U1, and then the current is integrated by the integrator through MOS tube Q1. When the input is a negative current, comparator U2 outputs a low level and comparator U3 outputs a high level. At this time, MOS tube Q1 is turned off and MOS tube Q2 is turned on. The input negative current is integrated by the integrator through MOS tube Q1.

[0032] like Figure 5As shown, this embodiment provides a schematic diagram of an integrator and a first comparator, the integrator and the first comparator are respectively denoted as comparator U4 and comparator U5; the non-inverting input terminal of the comparator U4 is grounded, the inverting input terminal is connected to the current output by the positive and negative current processing module, the capacitor C1 is connected between the output terminal and the inverting input terminal of the comparator U4, the positive power supply terminal of the comparator U4 is connected to the +15V power supply, and the negative power supply terminal is connected to the -15V power supply, one end of the resistor R7 is connected to the output terminal of the comparator U4, and the other end is connected to the non-inverting input terminal of the comparator U5 and the common end of the resistor R8, and the other end of the resistor R8 is grounded; the non-inverting input terminal of the comparator U5 is connected to the output of the integrator, the inverting input terminal is connected to the common end of the resistor R9 and the resistor R10, the other end of R10 is connected to the +15V voltage source, and the other end of R9 is grounded, the positive power supply terminal of the comparator U5 is connected to the +15V power supply, the negative power supply terminal is connected to the -15V power supply, the output of the comparator U5 is connected to the resistor R11, and the other end of the resistor R11 is connected to the +5V voltage source.

[0033] Capacitor C1 is connected between the inverting input and output of comparator U4, causing comparator U4 to function as an integrator. The voltage source, resistors R9, and R10 form a path that provides a threshold voltage for comparator U5. When input current enters integrator U4, capacitor C1 charges, causing the integrator's output voltage to decrease. When the output voltage of integrator U4 drops to the threshold voltage, the output signal of comparator U5 flips, changing from a high level to a low level.

[0034] like Figure 6 As shown, the logic control module includes a digital logic circuit, a first logic operation circuit and a second logic operation circuit; the input end of the digital logic circuit is respectively connected to the clock module and the output end of the first comparator, the output end of the digital logic circuit is respectively connected to the input end of the first logic operation circuit and the second logic operation circuit, the input end of the first logic operation circuit and the second logic operation circuit are also respectively connected to the control end of the second comparator and the third comparator, and the output end of the first logic operation circuit and the second logic operation circuit serve as the output end of the logic control module.

[0035] The switch module includes a third electronic switch and a fourth electronic switch, wherein the control ends of the third electronic switch and the fourth electronic switch are respectively connected to the output ends of the first logic operation circuit and the second logic operation circuit, one contact end of the third electronic switch and the fourth electronic switch are connected to form a contact common end, two contact ends of the third electronic switch and the fourth electronic switch are connected to form contact common ends, one contact common end is connected to the input end of the integrator, and two contact common ends are connected to the output end of the constant current source.

[0036] The input positive and negative currents enter the integrator through the positive and negative current processing module to charge the integration capacitor, and the output voltage of the integrator decreases. When the voltage drops to the threshold voltage of the first comparator, the output signal of the first comparator is flipped, and the output of the first comparator changes from a low level to a high level. At this time, under the drive of the clock signal CLK of the external clock module, the output signal FO+ or FO- of the first logic operation circuit and the second logic operation circuit.

[0037] FO+ and FO- serve as control signals for the third and fourth electronic switches. When the third or fourth electronic switch switches from the off state to the on state, the current output by the constant current source is applied to the input of the integrator. The constant current source output current is greater than the input current, forcing the integrator into a discharge state. At this point, the integrator's output voltage gradually increases. When the output voltage reaches the threshold voltage of the first comparator, the first comparator's output signal flips from high to low. The output of the logic control module also flips from high to low, causing the electronic switch to switch from the on state to the off state, isolating the constant current source and returning the integrator to the charging state. This cycle repeats, achieving current-to-frequency conversion.

[0038] like Figure 7 As shown, this embodiment provides a schematic diagram of a logic control module; the digital logic circuit, the first logic operation circuit, and the second logic operation circuit are respectively denoted as a flip-flop D1A, an AND gate D2A, and an AND gate D2B; the input terminal D of the flip-flop D1A is connected to the output terminal of the comparator U5 and to the clock signal CLK, and is configured to trigger the comparison signal of the comparator U5 using the clock signal CLK to generate a trigger pulse. The set terminal SET and the reset terminal CLR of the flip-flop D1A are both connected to a +5V power supply; two AND gates D2A and D2B are connected to the output terminal Q of the flip-flop D1A and grounded through a resistor R12; the AND gate D2A is connected to a resistor R15; the other end of the resistor R15 is connected to the gate of the MOS transistor Q1 in the positive and negative current processing module and the common end of the resistor R6; the AND gate D2B is connected to a resistor R13; the resistor R13 is connected to the gate of the MOS transistor Q2 in the positive and negative current processing module and the common end of the resistor R19; the two AND gates perform an AND operation to generate a frequency pulse signal. The output end of the AND gate D2A is connected to the resistor R14, the other end of the resistor R14 is connected to the gate of the MOS transistor Q3, and the source of the MOS transistor Q3 is connected to the negative input end of the integrator. The output end of the AND gate D2B is connected to the resistor R16, the other end of the resistor R16 is connected to the gate of the MOS transistor Q4, and the source of the MOS transistor Q4 is connected to the negative input end of the integrator. The drains of the two MOS transistors are connected to the constant current source.

[0039] The output signal of comparator U5, in conjunction with clock signal CLK, triggers the output of comparator U5 via trigger D1A. The output signal of trigger D1A enters AND gates D2A and D2B, respectively, and is ANDed with the current signal output by the comparator in the positive and negative current processing modules. The resulting output is a frequency pulse signal, which controls the on and off of the MOS transistors. MOS transistors Q3 and Q4 act as switches.

[0040] like Figure 8 As shown, the constant current source includes a voltage reference source, a voltage follower, and a second sampling resistor connected in series. The reference voltage output by the voltage reference source generates a reset current after passing through the voltage follower and the second sampling resistor. The reset current discharges the integrator through the third and fourth electronic switches.

[0041] The positive and negative output frequencies serve as control signals for the electronic switch to switch from an off state to an on state. At this time, the constant current source applies current to the integrator to control the discharge of the integrator. Since the input current is processed by the positive and negative current processing modules, the current input to the integrator is always a negative current. Therefore, the present invention only requires a positive constant current source reset circuit.

[0042] like Figure 9 As shown, the voltage reference source, the voltage follower, and the second sampling resistor are respectively denoted as the voltage reference source VR1, the comparator U6, and the resistor R17; the input terminal of the voltage reference source VR1 is connected to the +15V input voltage, the output terminal is connected to the non-inverting input terminal of the comparator U6, and the output terminal is connected to the inverting input terminal; the positive power supply terminal of the comparator U6 is connected to the +15V power supply, and the negative power supply terminal is connected to the -15V power supply; the output terminal of the comparator U6 is also connected to the resistor R17, and the other end of the resistor R17 is connected to the common end of the drain of the MOS tubes Q3 and Q4.

[0043] The frequency pulse signals FO- and FO+ control the on / off switching of MOS transistors Q3 and Q4. When the MOS transistors are on, a constant current source applies a reset current to the integrator's input, causing the integrator to enter an integrating and discharging state. This causes the integrator's output voltage to increase. When the voltage reaches the threshold voltage, the output signal of comparator U5 flips. When the MOS transistors are off, the constant current source is isolated, returning the integrator to a charging state. This cycle repeats, forming a circuit frequency conversion. Comparator U6's output is connected to its input, acting as a voltage follower.

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A current-frequency conversion hybrid integrated circuit, characterized in that: It includes a constant current source, a switch module, a clock module, and a positive and negative current processing module, an integrator, a first comparator, and a logic control module connected in series in sequence; the positive and negative current processing module is used to obtain the input positive and negative currents and output them separately; the integrator is used to obtain the output signal of the positive and negative current processing module and perform integration processing; the first comparator is used to obtain the output signal of the integrator and compare it with the threshold voltage; the logic control module is used to obtain the output signals of the first comparator and the clock module and generate a frequency pulse signal; the constant current source is connected to the integrator input terminal through the switch module contact terminal to provide a reset current for the integrator, and the switch module control terminal is connected to the logic control module output terminal; Wherein, the positive and negative current processing module includes a first sampling resistor, an operational amplifier, a first electronic switch, a second electronic switch, a second comparator and a third comparator; The first sampling resistor serves as an input end of the positive and negative current processing module, one end of the first sampling resistor is grounded, two ends of the first sampling resistor are respectively connected to the input end of the operational amplifier and one end of the second electronic switch contact, the output end of the operational amplifier is connected to one end of the first electronic switch contact, and two ends of the first electronic switch and the second electronic switch contact are connected to form an output common end and serve as the output end of the positive and negative current processing module; The positive input terminal of the second comparator is connected to the two terminals of the first sampling resistor, the output terminal of the second comparator is respectively connected to the first electronic switch control terminal and the negative input terminal of the third comparator, and the output terminal of the third comparator is connected to the second electronic switch control terminal; the negative input terminal of the second comparator and the positive input terminal of the third comparator are both grounded.

2. The current-frequency conversion hybrid integrated circuit according to claim 1, characterized in that: The logic control module includes a digital logic circuit, a first logic operation circuit and a second logic operation circuit; the input end of the digital logic circuit is respectively connected to the clock module and the output end of the first comparator, and the output end of the digital logic circuit is respectively connected to the input ends of the first logic operation circuit and the second logic operation circuit. The input ends of the first logic operation circuit and the second logic operation circuit are also respectively connected to the control ends of the second comparator and the third comparator, and the output ends of the first logic operation circuit and the second logic operation circuit serve as the output ends of the logic control module.

3. The current-frequency conversion hybrid integrated circuit according to claim 2, characterized in that: The switch module includes a third electronic switch and a fourth electronic switch, wherein the control ends of the third electronic switch and the fourth electronic switch are respectively connected to the output ends of the first logic operation circuit and the second logic operation circuit, one contact end of the third electronic switch and the fourth electronic switch are connected to form a contact common end, and two contact ends of the third electronic switch and the fourth electronic switch are connected to form contact common ends, the contact common end is connected to the integrator input end, and the contact common ends are connected to the constant current source output end.

4. The current-frequency conversion hybrid integrated circuit according to claim 1, characterized in that: The constant current source includes a voltage reference source, a voltage follower and a second sampling resistor which are sequentially connected in series.

5. The current-frequency conversion hybrid integrated circuit according to claim 1, characterized in that: The integrator includes a capacitor and a comparator, wherein the capacitor is connected between an output terminal and an inverting input terminal of the comparator.

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