SU1506368A1 - Electrometric charge converter - Google Patents

Abstract

This invention relates to a measurement technique and can be used in charge converters. The aim of the invention is to improve the noise immunity of the charge converter over power supply circuits. The charge converter contains an electrometric amplifier 1, an integrating capacitor 2, an analog switch 3, a compensation amplifier 4 of direct current, a tracking-5 block, an additional capacitor 6, a high-resistance resistor 7, a voltage divider on resistors 8 and 9, a non-linear resistor 10, performed on two anti-parallel emitter junctions of transistors 11 and 12, control unit 13, electrometric preamplifier 14 and operational amplifier 15. Electrometric preamplifier 14 contains two complementary pairs MOSFET transistors 16–19. Such an embodiment of the preamplifier 14 expands the dynamic range of the input signals and increases the noise immunity during the initial installation of the converter. 1 hp f-ly, 2 ill.

Description

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the charge isolator contains an electrometric amplifier 1, an integrating capacitor 2, an analog switch 3, a compensation amplifier 4 of direct current, a tracking-5 unit, an additional capacitor 6, a high resistor 7, a voltage divider on resistors 8 and 9 , nonlinear resistor 10, “made on two Yu Yu anti-parallel connected emitter transitions of transistors 11 and

12, control unit 13, an electromechanical preamplifier 14 and an operational amplifier 15. The electrometric preamplifier 14 contains two complementary pairs of MIS transistors 16 19. This embodiment of the preamplifier 14 expands the dynamic range of the input signals and increases the noise immunity during the initial setup of the converter. 1 hp f-ly, 2 ill.

This invention relates to electrical measuring technology.

The purpose of the invention is to increase the noise immunity of the power supply converter.

FIG. 1 shows a functional diagram of the converter; 2 shows timing diagrams for his work.

The electrometric charge converter contains an electrometric amplifier 1, the output of which is connected to the output of the device, an integrating capacitor 2 connected between the input of the device and the output of amplifier 1, an analog switch 3 connected in series between the output of amplifier 1 and its DC input amplifier 4 and tracking-storage unit 5, additional capacitor 6, high resistance resistor 7, voltage divider on resistors 8 and 9, nonlinear resistor 10, made on two counter and parallel connected 's emitter junctions of transistors 11 and 12 and control unit 13.

Electrometric amplifier 1 contains an electrometric preamplifier 14 and an operational amplifier 15. Electrometric preamplifier 14 is implemented in the form of an integrated circuit containing two complementary pairs of SchP transistors 16, 17 and 18, 19, the source and the substrate of the transistor 16 are connected to the n-type channel with the source bus The positive voltage (+ E), the source and the substrate of the transistor 17 with the p-type channel are connected to the bus of a negative voltage source (-E). The drains of the transistors 16 and 17 are connected to the output of the preamplifier 14 and the non-inverting input of the amplifier

15, the inverting input of which is connected to the common bus, and the output to the output of amplifier 1. The gates of transistors 16, 17 and 18, 19 are connected to the input of preamplifier 14 and information input of amplifier 1, drains and sources of transistors 18 and 19 are combined and connected to the compensation input the preamplifier 14 and, accordingly, the amplifier 1, the substrates of these transistors are connected respectively to the buses of the sources of positive (+ Е) and negative (-E) voltages.

Resistor 7 is connected between the input of the device and the input of amplifier 1. Nonlinear resistor 10 is connected between the input of amplifier 1 and the output of the voltage divider on resistors 8 and 9, to which a common bus is connected via switch 3 to the common bus. the capacitor 6, and the Second input - to the output of the amplifier 1. The input of the block 13 is connected to the Reset input of the device, the first output to the control input of the block 5 and the measurement resolution bus, and the second output to the control input of the switch 3.

The electrometric charge converter functions as follows.

After supplying the supply voltage, the output voltage of the electrometric amplifier 1 has a certain level that is different from zero (Fig. 2a, time interval). The residual output voltage of amplifier 1 is due to the voltage eto of the bias zero and the charge gain on the capacitor 2 during the transient process in the circuit of the device when the supply voltage of the voltages passes. Until time t 1, the command Reset

(Fig. 26) for the correction of the bias current of the zero of the electrometric amplifier 1 to the input of the block 13

voltage U, and the outputs of the last zero amplifier 4. However, when it is zero (Fig. 2, c, d). At the same time, the resultant input current, magnitude, key 3 remains closed, and the switch I decreases by a factor of. block 5 is in storage mode. Since, when the key is closed, 3 is not in the instant of time t4, the voltage U takes a low level, and block 5

the negative feedback, the elements of which are nonlinear resistor 10 and resistor 9, is open, then in the absence of measurable input signals, the change in output voltage of amplifier 1 determines em 15 of the tsiometric converter with the value of the integrated input Q (Fig. 2e), the current of the device. The input current, in turn, is determined by the sum of the parasitic insulator currents, the input bias current of amplifier 1 and parasite 20 rom 2. The output voltage U is the amplified current of the signal source, At the moment the bodies 1 are proportional to the level of input time t The first output of block 13, which can be performed, for example, in the form of two successively connected single-oscillators, appears to be turned out, a repeated voltage level is reset, the switch 3 of the discharging capacitor 2 is connected to tj. During the time interval t, -tj the non-linear negative feedback is closed and the integration of the output stage of the amplifier 1 of the saturation capacitor 2 occurs. The negative feedback circuit is disturbed and the input voltage of the preamplifier 14 is limited the level of the emitter transistor II or 12 (depending on the 5 transition of one of the transistors 11 on the polarity of the output voltage or 12, i.e. at a level of 0.6-0.7 V, electrometric amplifier 1) is 0.3 -0.5 V. At the time of transition to the mode storing and stores the compensation voltage value, which in the measurement mode is supplied to the compensation input of amplifier 1. At time t eleknaprimer input, output from a piezoelectric pressure sensor, which is converted to a current signal integrable condensate and has an opposite sign. After converting the input signal, before the next measurement of the displacement current of the charge converter. If overloads occur, i.e. at the moments of time, the voltage at the end of the time interval is determined by the voltage to lock the emitter junction of one of

as key 3 is closed. Thus, reliable protection of the preamplifier 14 against overloads is achieved.

as key 3 is closed. Thus, reliable protection of the preamplifier 14 against overloads is achieved.

nor tj voltage i, j takes low

level, and the voltage is high 0 input.

level, key 3 closes O During the introduction of the resistor 7

the time interval tj-t on the control unit with resistance R -, the output signal

The input of block 5 receives a high level signal, and block 5 is in tracking mode. The output voltage of amplifier 1 is amplified by amplifier 4 and through block 5 enters the compensation input of amplifier 1. Since the leakage resistance between the gate of MIS transistors 18 and 19 is tens and hundreds of giga, the output voltage i (Fig. 2e) is converted into a current whose magnitude is close to the magnitude of the input current of amplifier 1 and

device through the integrating capacitor 2 and the resistor 7 enters

45 to the input of the preamplifier 14 and attenuated N times, where, / Ro, RO is the resistance of the non-linear resistor 10, and RP is a non-linear function of the applied voltage

50 (the higher the voltage, the smaller the RO value). If we choose the ratio N such that the voltage for unlocking the pn junctions of transistors 11 and 12 correspond (or not opposite in sign). By the end they are much higher than) levels

time interval, the output voltage of amplifier 1 becomes close to zero. Its value is not equal to zero due to error

input signals at which the output stage of the operational amplifier 15 is saturated, then after the disappearance of the interference, the output

Statism due to the finite value of the gain of the amplifier 4 and due to the presence of the bias voltage of the zero of the amplifier 4. However, the resulting input current of the amplifier I is reduced by a factor of.

At time t4, the voltage U and takes a low level, and block 5

The Zrohmometric sensor transducer receives a signal Q (Fig. 2e), rom 2. The output voltage U of amplifier 1 is proportional to the level of the input voltage, the reset of the integrating capacitor 2 is repeated and the output stage of amplifier 1 is reloaded and the negative feedback circuit is broken, the input voltage of the preamplifier 14 is limited at the level of unlocking the emitter junction of one of the transistors 11 or 12, i.e. at the level of 0.6-0.7 V,

enters the storage mode and stores the value of the compensation voltage, which in the measurement mode is fed to the compensation input of amplifier 1. At time t, the signal Q is fed to the input of the electrometric converter zzr, figure 2. Output voltage U amplifier 1 is proportional to the input rhenium level, repeated reset of the integrating capacitor 2 is carried out and the output stage of the amplifier 1 is saturated and the negative feedback circuit is disturbed, the input voltage of the preamplifier 14 is limited at the output level wounds of the emitter junction of one of the transistors 11 or 12, i.e. at the level of 0.6-0.7 V,

for example, the output of the piezoquartz pressure sensor, which is converted to the current, integrated by the condensate-measuring converter, receives a signal Q (Fig. 2e), rum 2. The output voltage U of amplifiers 1 is proportional to the level of rhenium input, repeated resetting of the integrating the capacitor 2 and combo the output stage of the amplifier 1 is saturated and the negative feedback circuit is broken, the input voltage of the preamplifier 14 is limited at the level of unlocking the emitter junction of one of the transistors 11 or 12, i.e. at the level of 0.6-0.7 V,

signal and has the opposite sign. After converting the input signal, before the next isometric zzd converter, a signal Q is received (Fig. 2e), rom 2. The output voltage U of amplifier 1 is proportional to the level of input rhenium, repeated reset of the integrating capacitor 2 and the output the amplifier circuit 1 is saturated and the negative feedback circuit is disturbed, the input voltage of the preamplifier 14 is limited at the level unlocked by the emitter junction of one of the transistors 11 or 12, i.e. at the level of 0.6-0.7 V,

displacement current of the charge converter bias. If overloads occur, i.e. at the time points of the claw meter converter, the signal Q is received (Fig. 2e), rum 2. The output voltage U of amplifier 1 is proportional to the input r level, a repeated reset of the integrating capacitor 2 and the output stage of amplifier 1 are carried out the negative feedback circuit is saturated and disrupted, the input voltage of the preamplifier 14 is limited at the level unlocked by the emitter junction of one of the transistors 11 or 12, i.e. at the level of 0.6-0.7 V,

as key 3 is closed. Thus, reliable protection of the preamplifier 14 against overloads is achieved.

the entrance.

device through the integrating capacitor 2 and the resistor 7 enters

45 to the input of the preamplifier 14 and attenuated N times, where, / Ro, RO is the resistance of the non-linear resistor 10, and RP is a non-linear function of the applied voltage

50 (the greater the voltage, the smaller the RO value). If you choose the ratio N such that the voltage unlocked by the pn-junctions of transistors 11 and 12 correspond (or non-input signals that saturate the output stage of the operational amplifier 15, then after the noise disappears, the output voltage of the device is equal to the initial level. Thus The introduction of a resistor 7 makes it possible to increase the noise immunity of the electrometric converter.

The introduction of capacitor 6 posol zol reduces the amplitude of the impulse noise coming from the output of amplifier 15, as well as increases the stability of the control loop, including amplifier 1, voltage divider on the resistor 8 and 9, and nonlinear resistor 10.

Performing a preamplifier in the form of a complementary pair allows one to expand the dynamic range of the input signals (i.e., to expand the linear portion of the preamplifier operation) and to increase noise immunity during the initial installation of the converter.

Claims (2)

Invention Formula I, an electrometric charging converter containing an electrometric amplifier, the output of which is connected to the output of the converter and the second plate of the integrating capacitor, the first plate of which is connected to the input of the converter, is connected to the output of the electrometric amplifier, the output of which is connected to the input of the tracking-storage unit, the control input of which is connected to the first output of the control unit, the second output of which is connected to the control input of the analog switch, and the input - to the input Reset the converter, voltage divider, the output of which through a non-linear resistor is connected to the information input of an electrometric amplifier, so that, in order to improve the noise resistance. power supply, a resistor and an additional capacitor are inserted into it, and the electrometric amplifier is equipped with a compensation input, which is connected to the output of the tracking unit, the resistor is connected between the converter input and the input of the electrometric amplifier, the copper is switched on the first input of the voltage divider and the common bus of the converter, the second input of the voltage divider connected to the output of the electrometric amplifier, and the output through an analog switch is connected to the common bus of the converter. 2. Charge converter according to claim 1, characterized in that the electrometric amplifier is made on an electrometric preamplifier and an operational amplifier, the electrometric preamplifier being made as an integrated circuit containing two complementary pairs of EDP transistors, the source and the substrate of the transistor with the n-type channel of the first pair connected to the bus of a source of positive voltage, the source and the substrate of the transistor with the p-type channel of the first pair are connected to the bus of a source of negative voltage, drains of the transistors of the first The pairs are connected to a non-inverting input of an opera- tive 1D10NOG amplifier, the inverting input of which is connected to the common bus of the converter, and the output is connected to the output of an electrometric amplifier; the gates of the first and second pairs of transistors are connected to the information input of the electrometric amplifier, drains and sources of transistors with p-and p-types of the second pair are combined and connected to the compensation input of an electrometric amplifier; the substrates of these transistors are connected respectively to the buses of the positive and negative sources th voltage.