ISSN 0020-4412, Instruments and Experimental Techniques, 2015, Vol. 58, No. 4, pp. 483–487. © Pleiades Publishing, Ltd., 2015. Original Russian Text © O.V. Dvornikov, V.A. Chekhovskii, V.L. Dyatlov, N.N. Prokopenko, 2015, published in Pribory i Tekhnika Eksperimenta, 2015, No. 4, pp. 43–47.
ELECTRONICS AND RADIO ENGINEERING
An Integrated Circuit of a Universal Comparator O. V. Dvornikova, V. A. Chekhovskiib, V. L. Dyatlova, and N. N. Prokopenkoc* a
b
JSC Minsk Research Instrument-Making Institute, ul. Ya. Kolasa 73, Minsk, 220113 Belarus National Scientific and Educational Center of Particles and High-Energy Physics, Belarus State University, ul. Pervomaiskaya 18, Minsk, 220088 Belarus c Don State Technical University, pl. Gagarina 1, Rostov-on-Don, 344000 Russia *e-mail:
[email protected] Received July 18, 2014
Abstract—An ABMK-1.3 analog array chip for the high-precision detection of arrival times of signals in the wide frequency range in nuclear electronics is created. The chip contains a high-speed comparator with a built-in hysteresis and low-pass filter (LPF). The propagation delay of the comparator signal does not exceed 1.25 ns, and the hysteresis of the transfer characteristic can be regulated from 40 to 200 mV. The bandwidth of the LPF is below 130 kHz. The circuit design of separate stages of the chip and experimental characteristics are given. DOI: 10.1134/S0020441215030197
483
NС
IN B
OFFSET B
C2 B
C1 B 4
6
B
LPF 5
7 VCC
3
9
NС Cover
8 OUT B
2
10
GND
A
1
SEL A
OUT2 A
18
Comparator
OUT1 A
‒IN A
At present there are a set of commercial voltage comparators with a small delay and built-in hysteresis. Most comparators operate using the unipolar supply voltage, which is unified with the power supply of digital integrated circuits and possesses a very small hysteresis. These comparators are oriented at processing small high-frequency signals, since the increase in the hysteresis decreases the highest possible frequency, and the unipolar supply voltage limits the admissible peak-to-peak amplitude of input signals.
17 16 15 14 13 12 11
+IN A
Earlier we designed the multichannel discriminator (DISC-8.3), which was applied in the D0 experimental setup on the Tevatron accelerator–collider [1]. However, a relatively high propagation delay of the signal complicates the use of the DISC-8.3 discriminator in straw detectors with high loading capabilities and precision measurement of the longitudinal coordinate for up-to-date physical setups on high-current accelerators (CERN, FNAL, KEK, JPARK, and NIKA) [2, 3].
OUTLV2 A
The purpose of this paper is to consider the circuit design and parameters of the universal comparator, intended for the high-precision detection of low- and OUTLV1 A
In nuclear electronics, it is often required to detect the arrival time of the signal. For these purposes, a constant-threshold discriminator is applied in many cases. The discriminator is a voltage comparator one of the inputs of which is connected to the reference (threshold) voltage source. To exclude the repeated operation (“bounce”) of the discriminator, when the input signal exceeds the threshold, it is expedient to use comparators, which possess the hysteresis of the transfer characteristic.
There are known comparators (CLC2500, ADCMP580/581/582, and HMC674LC3C), which combine a high speed of operation and wide input signal range (from –2 to +2 V). However, the hysteresis value in them varies from 5 to 50 mV.
VEE+SUB
1. INTRODUCTION
Fig. 1. Structure of the microcircuit and pin configuration for the H04.18 package.
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(а) VCC
OUT 1А R1 100
R4
Q1
R5
Q2
70
Q30
R32
70
R35
1.9 kΩ
Q27
Q32
R33 OUT 1А
Q3
Q4
OUT 2А
R8 8.1 kΩ
Q5
R11
Q33
Q34
1.9 kΩ
Q35
R36
650
R9
650
8.1 kΩ
Q6
Q28
Q25
R34 OUTLV 1 OUTLV 2 3.8 kΩ
R10 1.9 kΩ
3.8 kΩ
R37 3.8 kΩ
VEE
R12 VEE 8.1 kΩ
VCC Q7
OUT 2А
R3 1.9 kΩ
R2 100
Q8
R13 8.1 kΩ
SELA VCC Q9
R14 3.8 kΩ
Q22
Q10
R15 Q26
GND Q12
Q11
VCC +INA
Q29
R17 5.8 kΩ
Q14
Q13
R16 15 kΩ
15 kΩ
R18 1.9 kΩ
‒INA Q18
Q15 R19 8.1 kΩ
R20 8.1 kΩ
Q17
Q16
R21 7.6 kΩ Q24
GND
Q20
Q19 R22 3.8 kΩ VEE
R23 325
Q21 R24 325
GND
R25 160
R26
Q23
R27
3.8 kΩ 8.1 kΩ
Q31
R28
R29
R30
R31
8.1 kΩ
1.9 kΩ
5.8 kΩ
3.8 kΩ
(b) VCC R6 5.05 kΩ GND R1 9.2 kΩ INB
R12 5.05 kΩ
R13 8.25 kΩ
Q1 C1B
Q8
Q13
C 2B Q11
R2
R3
R4
R5
5.8 kΩ
5.8 kΩ
5.8 kΩ
5.8 kΩ
С3
С4
С1
24.2 pF
24.2 pF
24.2 pF 24.2 pF
Q3 Q9 GND С2
VEE
OUTB
R7 90 kΩ Q12
Q2
Q6
Q4 Q5
R8 5.05 kΩ
R9 R10 5.05 kΩ 56.7 kΩ
Q10
Q14
Q7 R11 32.4 kΩ
R14 8.25 kΩ
VEE
OFFSET B
Fig. 2. Schematic diagrams of the: (а) comparator and (b) LPF.
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AN INTEGRATED CIRCUIT OF A UNIVERSAL COMPARATOR Output voltage level as function of the supply voltage for different pins of the comparator
KU 1.2 UINP = 3 V
Supply voltage, V Name of the pin OUT1A, OUT2A, OUTLV1A, OUTLV2A
1.0 ±5
±6
PECL –
– LVPECL
485
UINP = 0.1 V
0.8 0.6 0.4
The designed integrated circuit contains a highspeed comparator with a built-in hysteresis and lowpass filter (LPF). Figure 1 shows the structure of the integrated circuit, and the electric circuits of the comparator and the LPF are shown in Fig. 2. The electric circuits in Fig. 2 reflect the specific character of designing microcircuits on the AMBK1.3 array [4]: the required resistance value was obtained using the series–parallel connection of resistors with rated values of 70 Ω, 650 Ω, 1.25 kΩ, 5.8 kΩ, 8.1 kΩ, and 9.2 kΩ, which are admissible on the ABMK-1.3 array. To simplify the graphic picture, the figures show the total resistance value of the resistor chain. Thus, in Fig. 2а resistor R21 = 7.6 kΩ consists of four 1.9-kΩ series resistors. Note that in the electric circuits nets with the same designation are connected one to another. To maximally increase the speed of operation of the comparator (Fig. 2а), its input voltage is converted by the differential stage Q16, Q17, Q19 into the current, which is amplified by the subsequent stages and inversely converted into the voltage at resistors R1 and R2. The emitter followers Q1 and Q2 ensure the required loading capability, and resistor R11, being the element of the positive feedback, raises the gain of the comparator and generates the small hysteresis into the transfer characteristic. Transistors Q32 and Q33 with resistors R32, R33, R34 are intended for shifting the constant level and matching the output voltages with LVPECL logic levels (see the table). The comparator allows one to change the polarity of the output signal, when the voltage is applied to the pin SELA. When voltage USELA = 0 V, the pins OUT1A, INSTRUMENTS AND EXPERIMENTAL TECHNIQUES
0 101
102
103
104
105
106 F, Hz
Fig. 3. Dependence of the gain of the LPF KU on the frequency F at the different input signals.
OUTLV1A are noninverting outputs and OUT2A, OUTLV2A are inverting. When USELA ≥ 5 V, pins OUT2A, OUTLV2A are noninverting, and OUT1A, OUTLV1A are the inverting outputs. The LPF is the fourth-order filter and allows one to decrease the bandwidth, if the external capacitors are connected to pins C1B and C2B. Its frequency response is shown in Fig. 3. To confidently detect low-frequency signals, it is recommended to ensure the series connection of the LPF and comparator. In this case, it is expedient to decrease the bandwidth of the LPF using external capacitors and/or to increase the hysteresis of the comparator by introducing the resistive divider (Fig. 4). VIN VTH R1 51
R2 56
VCC
R3 1.1 kΩ
VEE 8 7 6 5 4 3 2
2. FEATURES OF THE STRUCTURE AND THE CIRCUIT
0.2
9 10
1
H04.18 11 12 13 14 15 16 17
high-frequency signals for high energy physics in an input voltage range of –2 to +3 V. The integrated circuit is created on the ABMK-1.3 analog array, which is manufactured at the Transistor Branch of the JSC Integral (http://www.integral.by/).
R4 1.1 kΩ VCC VOUT
18
SY55855V
R5 100
Fig. 4. Layout scheme of the comparator in measurements of the propagation delay. Vol. 58
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tPD, ns
tPD, ns
1.6
2.4 2.3 2.2 2.1 2.0 1.9 1.8 1.7 1.6 1.5
1.5 1.4 1.3 UTHR = 50 mV
1.2 1.1 1.0
UTHR = 300 mV
0.9 0.8
0
0.5
1.0
1.5
2.0
2.5
3.0 UOD, V
UTHR = 300 mV
UTHR = 50 mV 0
0.5
1.0
1.5
2.0
2.5
3.0 UOD, V
Fig. 5. Dependence of the propagation delay tPD at the output of the comparator on the overdrive voltage UOD at different thresholds UTHR.
Fig. 6. Dependence of the propagation delay tPD at the output of the Micrel SY55855V level translator on the overdrive voltage UOD at different threshold values UTHR.
3. EXPERIMENTAL RESULTS
The selected structure, attained parameter level, and possibility of increasing the hysteresis of the comparator and decreasing the bandwidth of the LPF using external RC elements allow one to apply the created microcircuit for processing both low- and highfrequency signals with different shapes and values, e.g., sinusoidal signals with an effective value of 20 mV–1 V and frequency of 10 Hz–400 MHz.
In the studies of the speed of operation the designed microcircuit was connected in accordance with Fig. 4. The propagation delay was measured at the output of the comparator and the Micrel SY55855V level translator using the MSO6052A two-channel oscilloscope (Agilent Technologies, Inc.), I1-15 pulse calibrator, and probe with an input resistance of 2.2 MΩ and capacitance value of 12 pF. In this case, the measurement accuracy of time parameters was limited by the rise time of the signal in the probe–oscilloscope system, which was about 700 ps, and by the parameters of the SY55855V microcircuit. In the measurements the constant threshold voltage (pin VTH) was set and the amplitude of the input signal (pin VIN) was changed from zero to the maximal value. The propagation delay was evaluated at a level of 0.5 (Fig. 5) at the minimally possible hysteresis of the comparator. The change of the resistance value of resistor R2 (Fig. 4) ensured the regulation of the hysteresis value in the wide range: Resistance value of resistor R2, Ω 56 Hysteresis value, mV
240
560
820
60 122.5 181.25 215
Figure 6 characterizes the propagation delay tPD. As a result of the performed measurements, it was determined that the designed microcircuit is characterized by the following basic parameters: the propagation delay of the comparator signal does not exceed 1.25 ns at UOD = 0.2 V and UTHR = 50 mV; the built-in hysteresis value is 40 mV; the hysteresis regulation range is up to 200 mV; the admissible input signal range is from –2 to +3 V; and the LPF bandwidth is <130 kHz.
4. CONCLUSIONS The integrated circuit that includes the high-speed comparator and LPF is created on the АBMK-1.3 analog array. The comparator is characterized by the propagation delay of no more than 1.25 ns, admissible range of input signals from –2 to +3 V, and the built-in hysteresis value of 40 mV. The LPF bandwidth is below 130 kHz. The application of external RC elements decreases the bandwidth of the LPF and increases the hysteresis of the comparator. The microcircuit was applied in the test bench equipment, used for designing the procedure and creating large-area tracking detectors on thin-walled wire detectors (straw tubes) with improved characteristics in cooperation with the Belarussian Foundation for Fundamental Research, National Academy of Sciences of Belarus, and the Joint Institute for Nuclear Research (Dubna, Russia), project no. F14D-006 dated May 23, 2014. The studies were supported by the Belarus Republic State Program of Research “Information Science and Space, Scientific Provision of Security and Protection against Emergency Situations,” job no. 3.3.10, and the Russian Federation Ministry of Education and Science, project no. 8.374.2014/K of the State job for 2014–2016.
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Translated by N. Pakhomova
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