Click model number for photo
- Optimized for Proportional Wire Applications
- Multi-pole Shaping And Tail Cancellation
- Very High Gain (4.3 µV/Electron or 27 mV/fC Typical)
- Easy to Use
- Differential Output (With 2 V Linear Differential Swing)
- Negative or Positive Charge Input
- 230 ohm Input Impedance
- Low Noise - Typically < 3000 Electrons RMS With 20 pF Input Capacitance
HIGH GAIN AMPLIFIER FOR MULTIWIRE PROPOR TIONAL CHAMBERS
The MQS104A is a bipolar monolithic, 4-channel preamplifier optimized for
proportional chamber applications. Integrated on the chip with the preamplifier
is a 4-pole shaping amplifier. The impulse response is an 18 nsec wide pulse
with 10 nsec rise time and 18% undershoot. This is a good match for a typical
proportional chamber (30 nsec drift time) and results in a 50 nsec wide
output pulse with no undershoot. The MQS104A is packaged as a 28-pin PLCC
for high density surface mount printed circuit boards.
The differential output has a quiescent DC level of 7 V, and less than 0.5
V offset. The output is intended to be AC coupled to a differential comparator
or discriminator. The threshold can be as low as 1 fC (15K electrons). The
differential output is linear up to 32 fC (200K electrons) input impulse
charge. Inputs up to 64 fC saturate only the output stage, allowing immediate
recovery without disturbing the tail cancellation. The input DC level is
self biased to 0.7 V allowing simple protection circuits and direct connection
to a proportional chamber sense wire floating near ground. The input should
be driven from a very high impedance source (typically a collection wire
Power Supplies: 37 mA typical, 50 mA maximum at +10 V; 19 mA typical,
24 mA maximum at +5 V; 10 mA typical, 13 mA maximum at -2 V; Total dissipation
485 mW typical.
Charge Gain: 4.3 µV typical (27 mV/fC) ±30%.
Input Impedance: 230 ohm, ±30% at 10 MHz.
Output Impedance: 90 ohm, ±30%.
Maximum Input Signal for Linear Output: 200K electrons (32 fC) with
no load on outputs.
Noise (RMS): < 3000 electrons (0.4 fC) typical with 20 pF on input.
Impulse Response: 10/90 rise time 10 nsec; pulse width (FWHM) 18
nsec; undershoot 18%, 80/20 undershoot recovery 30 nsec. All time specifications
are ±30% measured with 2 pF injection capacitor.
Adjacent Input Crosstalk: 2% maximum (with open circuit output).
Crosstalk to Non-Adjacent Inputs: < 1% typical < 2% maximum.
Quiescent Output Level: 7 V DC ±1 V.
Differential Output Signal: < ±500 mV DC offset.
Input Bias Voltage: +0.7 V (internally generated).
MQS104A Pin Out Diagram
The MQS104A normalized response to a capacitively coupled voltage step with
measurements illustrated. Click here for graph.
Gain vs. Input Capacitance Graph
Gain vs. Input Pulse Rise Time Graph
Equivalent RMS Input Noise vs. Input Capacitance
Output Noise vs. Input Capacitance Graph
Input Impedance vs. Frequency
Noise Test Setup Diagram. All power supplies
decoupled to ground by a 0.1 µF capacitor.
Gain Test Setup Diagram. All power supplies decoupled
to ground by a 0.1 µF capacitor. Gain vs. capacitance used square pulse
with rise time of 0.9 nsec into varying capacitance. Gain vs. rise time
used fixed injection capacitance of 1.8 pF.
Typical circuit using MQS104A (MQS104TB demonstration
Copyright© September 1995. LeCroy is a registered trademark of LeCroy
Corporation. All rights reserved. Information in this publicaction supersedes
all earlier versions.