C2719

MODULE Photosensor amplifier C2719 Current-to-voltage conversion amplifier for amplifying weak photocurrent with low noise C2719 is a current-to-voltage conversion amplifier used to amplify weak photocurrent from a photodiode with very low noise. Three ranges of photocurrent detection sensitivity level (H, M, L) are selectable to match the input signal. A 10-turn potentiometer is used to zero the amplifier level so fine adjustments are possible with high resolution. C2719 operates on the built-in dry batteries so it can be easily used anywhere. An external power input connector is also provided at the rear panel for a long, continuous operation or for use as part of a measurement system. In such applications, use the dedicated plug to connect to a stabilized DC power supply. C2719 was developed specifically for use with Si photodiodes, but it can be used to detect photocurrent from phototubes. Features Applications l Three9sensitivity ranges H: 10 V/A M: 107 V/A L : 105 V/A l Zero adjustment with high resolution l Operates on either dry batteries or external power supply l Compact and lightweight l Precision photometry l Laser monitors l Optical power meters l Colorimeters l Low signal current preamplifiers I General ratings (Ta=25 °C) Parameter Condition Min. ±5 (±10) Output voltage amplitude RL=2 kW Offset drift Offset temperature characteristic Input voltage Recommended input capacitance *1 Supply voltage External power supply ±6 Battery lifetime 200 RL>10 kW Weight Including batteries Value in parentheses is measured when external power supply is used. *1: Batteries: 006 P (9 V) × 2 pieces Typ. ±9 420 Max. ±0.1 ±25 ±100 2 × 10 ±15 -9 Unit V mV/hr µV/°C V F V V hr g I Electrical and optical characteristics (Ta=25 °C) Parameter Conversion impedance Input current range Frequency bandwidth Output noise * 2 (all bandwidth) Equivalent noise -14 -12 -10 -14 2 × 10 2 × 10 2 × 10 2 × 10 input current *2: Measured with a 1.6 kHz lowpass filter added to the output of C2719. Internal batteries (Vs=±9 V) H M L 109 107 105 to ±5 × 10-9 to ±5 × 10-7 to ±5×10-5 DC to 16 DC to 1600 DC to 1600 0.2 0.2 0.2 0.02 0.02 0.02 External power supply (Vs=±15 V) H M L 109 107 105 to ±10×10-9 to ±10×10-7 to ±10×10-5 DC to 16 DC to 1600 DC to 1600 0.2 0.2 0.2 0.02 0.02 0.02 2 × 10 -12 Unit V/A A Hz mVp-p mVrms A 2 × 10 -10 1 Photosensor amplifier I Equivalent circuit Figure 1 Equivalent circuit (when photodiode cathode is grounded) Cf2 Rf3 Rf2 Rf1 L M H 006P (9 V) × 2 C2719 Cf1 +Vs PHOTOCURRENT SIGNAL i LIGHT A K 330 A Vout = -(i × Rf) +Vs PROTECTION CIRCUIT + ZERO ADJ -Vs + -Vs 0V + EXTERNAL POWER SUPPLY TERMINAL HR10-7R-4P (HIROSE) (CASE) KACCC0030EC KACCC0031EA In the equivalent circuit diagram (Figure 1), the photocurrent signal i is connected to the input terminal of the negative feedback amplifier A. The input resistance of A is designed to be much larger than feedback resistance Rf, so all of i is flows through Rf. The result is that the output voltage of A is converted to -i × Rf (V), the reverse phase of i. Rf is switched to the High, Medium and Low ranges by the conversion impedance, with Medium being 1/100 of High and Low being 1/10000 of High. Feedback capacitance Cf is 10 pF (1 nF + 10 pF at Low range) to prevent the circuit from becoming unstable at high frequencies. In this case, the cut-off frequency is calculated as follows: f= 1 (Hz) 2 π Cf Rf Figure 2 Output response waveform (S2281 + E2573) (a) H range At this frequency, the output voltage is 0.7 times that at the low frequency. I Pulsed light measurement G Output response waveform If the photodiode terminal capacitance is approximately 2 nF or more, ringing may appear in the output waveform of C2719 when pulsed light is detected, resulting in inaccurate measurements. In this case, use a photodiode with a smaller terminal capacitance, or add a reverse voltage to the photodiode to reduce the terminal capacitance. Figures 2 (a) and (b) show pulse response waveforms when used with S2281 photodiode which is designed to easily connect to C2719. The terminal capacitance of S2281 is 1.28 nF. G Frequency response Figure 3 shows the frequency response characteristics when used with S2281. As stated above, if the photodiode terminal capacitance is too large, a noticeable peak is formed in the frequency characteristics. This situation is shown in Figure 4. A frequency at which this kind of peak exists equals the reciprocal of the ringing cycle generated in the pulse response output waveform. G S/N As explained above, when the terminal capacitance of a photodiode is too large, peaking exists in the noise characteristics even when there is no light input, making it impossible to obtain an accurate S/N during light measurement. Figure 5 shows the frequency characteristics of the signal and noise when S2281 is used. Here, peaking cannot be observed. ←LED drive pulse waveform (2 V/div.) ←Output waveform (2 V/div.) (b) L, M range ←LED drive pulse waveform (2 V/div.) ←Output waveform (2 V/div.) 2 Photosensor amplifier Figure 3 Frequency response (S2281 + E2573) 1010 H RANGE C2719 Figure 4 Gain peaking TERMINAL CAPACITANCE: Ct=12 nF 108 M RANGE 107 106 L RANGE OUTPUT VOLTAGE (10 dB/div.) 109 OUTPUT (V/A) TERMINAL CAPACITANCE: Ct=1.2 nF 105 104 103 0 10 101 102 103 104 105 106 KACCB0031EA 102 103 104 105 FREQUENCY (Hz) FREQUENCY (Hz) KACCB0032EA Figure 5 Frequency response of output signal and noise (S2281 + E2573) [Light source: Directly modulated laser diode (DC biased)] Figure 6 Schematic pursuit of gain peaking 106 NOISE GAIN, OPEN LOOP GAIN OUTPUT VOLTAGE (10 dB/div.) SIGNAL FREQUENCY RESPONSE 105 104 103 102 101 100 10-1 ' 10-2 f1 REF -17.0 dBm ATT10 dB TG LEVEL -10.0 dBm RBW 100 Hz VBW 300 Hz O PAM P O PE N LO O P G AI NOISE FREQUENCY RESPONSE N f1 101 102 f2 103 f3 104 105 106 107 108 0 1 2 3 4 5 10-3 10-1 100 FREQUENCY (kHz) KACCB0033EA FREQUENCY (Hz) KACCB0034EA I Selecting photodiodes As described previously, stable measurement may become impossible depending on the photodiode type. The diagrams are used here to explain how to select a correct photodiode which will not generate gain peaking when used with C2719. Figure 6 shows an example in which a photodiode with a terminal capacitance Ct of 1.28 nF and a shunt resistance*2 Rsh of 130 MΩ (See note below). In the low-frequency range ➀, the op-amp noise gain of C2719 is determined only by the ratio between Rsh and the feedback resistance Rf of C2719. Starting from frequency f1 at 1/ωCt > Rsh, the frequency increase is accompanied by an increase in gain over the interval indicated by ➁. Next, as the frequency increases from f2 at 1/ωCf > Rf, the circuit noise gain is determined by the ratio of Ct to Cf, during the interval indicated by ➂. Then, in the range covered by interval ➃, the noise gain decreases, with a slope identical to that of the op-amp open loop gain starting from the point where it contacts frequency f3, which normally decreases at 6 dB/oct. At this point, if Ct is multiplied by 10, f1 moves to f1’ and the setting of the noise gain rise at ➁ exceeds the curve of the op-amp open loop gain. This causes area ➂ to disappear. If this happens, C2719 can no longer maintain stable operation, and gain peaking appears. Consequently, it is necessary to make sure that area ➂ always exists. With C2719, Rf and Cf are determined by the sensitivity range. Thus, whether gain peaking occurs or not depends on the Ct value of the photodiode, so selecting the appropriate photodiode is essential. Figure 7 shows what happens to each of the sensitivity ranges of C2719 when used with S2281. *2: Shunt resistance Rsh= 10 mV ID (VR = 10 mV) 3 Photosensor amplifier Figure 7 Example of ranges 106 105 PHOTODIODE: S2281 C2719 I Operation example Figure 8 Typical application using S2281 photodiode PEN RECORDER NOISE GAIN, OPEN LOOP GAIN 104 103 102 101 H RANGE 100 10-1 M RANGE 10-2 KACCC0032EB LIGHT C2719 COAXIAL CABLE E2573 S2281 * * The output of C2719 is positive going because the anode of S2281 is grounded. A/D CONVERTER , etc. VOLTMETER 10-3 L RANGE 10-4 10-1 100 101 102 103 104 105 106 107 108 109 Figure 9 Typical application using an ordinary photodiode FREQUENCY (Hz) KACCB0035EA PHOTODIODE * LIGHT COAXIAL CABLE E2573 DARK BOX * The output of C2719 is negative going when the photodiode cathode is grounded, and is positive going when the anode is grounded. KACCC0033EB C2719 VOLTMETER , etc. Figure 10 Typical application using a phototube K LIGHT PHOTOTUBE COAXIAL CABLE E2573 DARK BOX KACCC0034EA C2719 VOLTMETER , etc. A Figure 11 Dimensional outline (unit: mm) INPUT BNC-R OUTPUT BNC-R EXTERNAL POWER SUPPLY I Accessories Plug for external power supply input HR10-7P-4S (HIROSE) Lead : AWG#24 (length: approx. 500 mm) Color: red (+Vs), blue (-Vs), black (GND) I Option E2573 BNC-BNC coaxial cable (coaxial cable: 1.5D-2V, cable length: 1 m) 90 PILOT LAMP POWER SUPPLY SWITCH ZERO ADJUSTMENT CONTROL Rf CHANGE SWITCH 114 39 KACCA0022EA 4 Photosensor amplifier C2719 I Precaution for use G When an external power supply is used for C2719, voltage is supplied regardless of whether the power switch of C2719 is on or off. Use the power switch of the external power supply to turn voltage on and off. G There are photodiodes whose cathode is connected to the metal package. To connect the cathode of such a photodiode to C2719, be sure to hold the photodiode with insulator as shown in Figure 12. The signal current cannot be obtained if the photodiode package is grounded. G Avoid using C2719 in locations subjected to excessive vibrations. If unavoidable, use a low-noise coaxial cable as the signal input cable. G In low-light-level detection circuits, insulation resistance of the circuit board and other insulation materials can affect measurement accuracy. Avoid humidity and soiling. G Noise increases when the input capacitance becomes larger, so keep the input coaxial cable as short as possible. G Remove the batteries when C2719 is not to be used for a long period. G An input protection circuit is incorporated, but even so, do not apply more than ±100 V. G For external power supply, use a regulated DC power supply with a ripple of less than 3 mVp-p. Make sure that the supply voltage does not exceed ±15 V even momentarily. Avoid using a switching power supply, as this can K A TO C2719 Figure 12 Connection to photodiode whose cathode is connected to metal package INSULATOR LIGHT cause noise problems during measurement. PHOTODIODE PACKAGE METAL CASE KACCC0035EA Photosensor amplifier C6386 Hamamatsu also provides C6386 high-speed photosensor amplifier that incorporates a photodiode at the installation port of the optical fiber (1 meter long). Features Built-in photodiode allows easy detection of light just by connecting to a voltmeter. l Optical fiber light input Measures light at a narrow detection point. Separating the amplifier from the detection point allows measurement in unusual environments and improves S/N. l High-speed response l Three sensitivity ranges l Easy handling Range H M L Photocurrent Cut-off frequency detection sensitivity # 10 V/A 1 MHz " 10 V/A 3 MHz 10!V/A 10 MHz 5 PHOTODIODE Si photodiode S2281 series Si photodiode with BNC connector S2281 series photodiodes are sealed in a metal package with a BNC connector and designed to simply connect to C2719 photosensor amplifier (S2281-01 has a large terminal capacitance which may cause a gain peaking to occur when C2719 is used with the gain set to the "M" range.) Two different spectral response ranges are provided. The large active area makes S2281 series suitable for optical power meters. A variant type S9219 with a visual compensation filter is also available.Hamamatsu also provides E2573 BNC-BNC coaxial cable (length: 1 m) as an option. I G e ne ra l ra ting s P a ra m e te r A c tive a re a s iz e A c tive a re a P ackage W in d o w m a te ria l S2281 f 1 1 .3 100 S 2 2 8 1 -0 1 f 1 1 .3 100 M e ta l w ith B N C c o n n e c to r Q u a rtz g la s s S 2 2 8 1 -0 4 f 7 .9 8 50 U n it mm 2 mm - n Absolute maximum ratings P a ra m e te r R e v e rs e vo lta g e O p e ra tin g t e m p e ra tu re S to ra g e te m p e ra tu re S ym bol V R M a x. Topr T s tg S2281 S 2 2 8 1 -0 1 5 -1 0 to + 6 0 -2 0 to + 7 0 S 2 2 8 1 -0 4 U n it V °C °C I E le c tric a l an d o ptic a l c ha ra c teris tic s (T a = 25 ° C , u nles s oth erw is e n ote d) P a ra m e te r S p e c tra l re s p o n s e ra n g e P e a k s e n s itivit y w a ve le n g th P h o to s e n s itivit y S h o rt c irc u it c u rre n t D a rk c u rre n t Shunt re s is ta n c e R is e tim e T e rm in a l c a p a c ita n c e Noise equivalent power Symbol l lp S Is c ID Rsh tr Ct NEP l=200 nm l=lp 1 0 0 lx VR=10 m V VR=10 m V VR=0 V R L= 1 k W VR=0 V f= 1 0 k H z C o n d itio n M in . 0 .1 0 64 20 S2281 T yp . 1 9 0 to 1100 960 0 .1 2 0 .5 80 50 200 3 1300 2.0´ 10-14 M a x. 500 - M in . 0 .1 0 32 30 - S 2 2 8 1 -0 1 T yp . M a x. 1 9 0 to 1000 720 0 .1 2 0 .3 6 40 6 1700 7 3200 8.6´ 10-15 M in . 0 .1 0 32 20 - S 2 2 8 1 -0 4 T yp . M a x. 1 9 0 to 1100 960 0 .1 2 0 .5 40 50 200 3 1300 1.8´ 10-14 U n it nm nm A /W µA pA MW µs pF W /H z 1 /2 300 - 500 - I Spectral response 0.7 (Typ. Ta =25 ˚C) 0.6 I Dimensional outline (unit: mm) S2281,S2281-01 S2281/-04 S2281-04 25.0 ± 0.1 17.5 ± 0.1 7.98 ACTIVE AREA (50 mm2) 5.0 ± 0.2 10.0 ± 0.1 16.0 - 0.1 PHOTO SENSITIVITY (A/W) 17.5 ± 0.1 0.4 0.3 0.2 0.1 S2281-01 11.3 ACTIVE AREA (100 mm2) GLASS WINDOW ( 1000 KSPDB0090EA BNC : UG-625B/U CORE: CATHODE CASE: ANODE ) KSPDA0080EA 190 400 600 800 WAVELENGTH (nm) Information furnished by HAMAMATSU is believed to be reliable. However, no responsibility is assumed for possible inaccuracies or omissions. Specifications are subject to change without notice. No patent rights are granted to any of the circuits described herein. ©2003 Hamamatsu Photonics K.K. HAMAMATSU PHOTONICS K.K., Solid State Division 1126-1 Ichino-cho, Hamamatsu City, 435-8558 Japan, Telephone: (81) 053-434-3311, Fax: (81) 053-434-5184, http://www.hamamatsu.com U.S.A.: Hamamatsu Corporation: 360 Foothill Road, P.O.Box 6910, Bridgewater, N.J. 08807-0910, U.S.A., Telephone: (1) 908-231-0960, Fax: (1) 908-231-1218 Germany: Hamamatsu Photonics Deutschland GmbH: Arzbergerstr. 10, D-82211 Herrsching am Ammersee, Germany, Telephone: (49) 08152-3750, Fax: (49) 08152-2658 France: Hamamatsu Photonics France S.A.R.L.: 8, Rue du Saule Trapu, Parc du Moulin de Massy, 91882 Massy Cedex, France, Telephone: 33-(1) 69 53 71 00, Fax: 33-(1) 69 53 71 10 United Kingdom: Hamamatsu Photonics UK Limited: 2 Howard Court, 10 Tewin Road, Welwyn Garden City, Hertfordshire AL7 1BW, United Kingdom, Telephone: (44) 1707-294888, Fax: (44) 1707-325777 North Europe: Hamamatsu Photonics Norden AB: Smidesvägen 12, SE-171 41 Solna, Sweden, Telephone: (46) 8-509-031-00, Fax: (46) 8-509-031-01 Italy: Hamamatsu Photonics Italia S.R.L.: Strada della Moia, 1/E, 20020 Arese, (Milano), Italy, Telephone: (39) 02-935-81-733, Fax: (39) 02-935-81-741 6 Cat. No. KACC1011E05 Feb. 2003 DN +0 0.5 25.0 ± 0.1