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2262 QUAD WAVEFORM DIGITIZER

FOR HIGH RESOLUTION RECORDING OF FAST SIGNALS


The Model 2262 is a high-speed, waveform digitizer providing high resolution, multichannel solutions to waveform recording requirements. Designed in a modular standard for ease of system configuration, the 2262 offers four digitizers per module. The 2262 is compatible with CAMAC (IEEE-583), and works with IBM PC-based software for easy, user oriented, waveform display and control.

The 2262 is DC-coupled with an analog bandwidth in excess of 40 MHz. User selectable sampling rates up to 80 MS/sec coupled with 10-bit resolution and dynamic range match a broad spectrum of applications. The 2262 excels in applications such as chamber and detector development for nuclear physics.

FEATURES

Fast Digitizing Rate - Standard sampling rate is 40 megasamples/sec. The 2262 Biphase Mode results in doubling (80 megasamples/sec) of the sample rate at the expense of two signal inputs.

Multiple Independent Inputs - Each 2262 has four inputs and is capable of measuring four waveforms simultane ously at the sampling frequency or two waveforms at double that frequency.

Built-in Calibration Trim DACs - Internal DACs allow calibration under software control to ensure maximum fidelity of measurement regardless of the time and temperature.

High Resolution - A wide 10-bit dynamic range gives 1.5 mV resolution over a full scale of 1.53 V, providing maxi mum detail capture in the measurement.

Convenient Test Capability - Front-panel input applies identical test signals to all four channels.

Bipolar Operation - Input range is a full 1.5 V, offset anywhere between -1.5 V and +1.5 V to ensure adaptability to the polarity characteristics of the signal.

Fast Clear Input - Should post-trigger factors demand, fast clear allows simultaneous conversion abort in all chan nels. Readies the 2262 for a new measurement.

Internal or External Time Base - Instead of the internal crystal oscillator, an external time base can be used to introduce a custom clock and to permit the synchronization of more than one 2262.

Very High Density - Up to 40 recording channels can be accommodated in a standard LeCroy Model 8025 rack -mount power housing. Up to 80 channels can be implemented with external +12 V power.

GPIB (IEEE 488) and/or CAMAC (IEEE 583) Programmable - The 2262 plug-ins can be controlled and read out by LeCroy Model 8901A interface and GPIB or via any direct standard CAMAC interface available for a variety of computers.

FUNCTIONAL DESCRIPTION

The Model 2262 is a multichannel waveform digitizer based upon the LeCroy MVV200 high performance charge coupled device (CCD). It may be operated in one of two modes, Uniphase or Biphase. Uniphase mode provides four channels at up to 40 MHz sampling rates. Each of the four channels has a record length of 316 samples. In the Biphase mode, two channels are internally tied to one input connector and alternately sampled to provide an effective sampling rate up to 80 MHz and a record length of 632 samples.

The signal to be digitized may be connected directly to the 1.5 V full-scale input or via a modular amplifier (LeCroy 6103) if gain control is required. The operating range of 1.5 V may be offset via front-panel control over a range of anywhere between -1.5 V and +1.5 V. Test points at the front panel monitor the offsets to facilitate settings. Internal calibration DACs allow fine trimming of offset characteristics via software control to ensure maintenance of full dynamic range during use.

The 2262's sample clock can be internally or externally driven. The clock source is controlled by a front-panel switch. The internal clock is a plug-in hybrid crystal oscillator which provides a stable, free-running time base. An 80 MHz oscillator is factory supplied with the unit. The oscillator is followed by a 2:1 divider to generate the 40 MHz sampling clock with a precise 50% duty cycle. Use of an external clock provides convenient variable-speed sampling. The CLK OUT feature may be used to synchronize two or more 2262s to the same time base.

The Model 2262 is a 100% pretrigger device, i.e., when the stop signal is applied, the CCDs are stopped and the last 316 cells (632 cells for Biphase mode) are available for digital conversion and read out.

An analog test input on the front panel provides a signal path to all four channels for calibration purposes. When selected, the normal inputs are internally disconnected. This signal path provides a convenient means to verify operation of each channel.

The Model 2262 is in CAMAC format (IEEE-583). Many interfaces, control and accessory modules exist for application-oriented system configurations. GPIB control is available from LeCroy using the Model 8901A GPIB interface. This allows virtually any computer with a IEEE-488 (GPIB) interface to control and read out the digitiz ers and any associated supporting system modules. LabWindows is available to create a user-friendly atmo sphere for the 2262 as well as to set up a convenient vehicle for the addition of customized user-software.

SPECIFICATIONS

SIGNAL INPUT CHARACTERISTICS

Number of Signal Inputs: 4 in Uniphase mode; 2 in Biphase mode.

Amplitude Range: 1.53 V p-p (1.5 mV/LSB) ±2%.

Impedance: 50 ohm ±5% DC.

Bandwidth: DC to > 40 MHz (-3 dB).

Slew Rate: > 120 V/µsec, typically 150 V/µsec.

Offset Range: Two front-panel screwdriver adjustments; one for Channels A1 and A2 and one for B1 and B2. Operating range may be set to cover any 1.5 V range between -1.5 V and +1.5 V.

Monitor Test Points: Two front-panel probe points for offset monitoring. Range -1.5 V to +0 V. (The voltage measured is the most negative point of the input voltage range.)

Overload Recovery: Recovers to ±1% of full scale within 2 samples of 2 x overdrive pulse.

Overload Protection: ±5.0 V.

Test Input: Lemo connector; impedance 50 ohm ±5%. When selected, signal is sampled by all four channels. When no connection is made, the digitizing of the Test input provides a convenient ground reference for offset measurement.

OUTPUT CHARACTERISTICS

Record Length: 316 samples for Uniphase mode; 632 for Biphase mode. Maximum data record length may be reduced by hardware option in modules for specialized applications, reducing both conversion and readout time.

Resolution: 1.5 mV.

Digital Format: 10 bits (1024 counts).

AC Accuracy: Ranges from ±0.25% to ±1.5% depending upon input signal frequency and amplitude. See instruction manual for specific performance curves.

Non-linearity: ±0.5% of best straight line fit over the operating range.

Random Noise: < 1 count R.M.S. (With respect to best straight line through RSO (Rate-of-Signal Offset).)

Spatial Noise: < 3 counts p-p; stable to < 1 count under constant frequency and temperature operation. The first 2 bins of each channel are excluded from the spatial noise specification. (With respect to best straight line through RSO (Rate-of -Signal Offset).)

Gain Temp Coefficient: < ±1000 ppm/°C.

Offset: Temperature coefficient: < 1 count/°C.

Droop: A linear change of offset from sample to sample. Increases with ambient temperature and/or acquisition clock rate. Unadjusted Droop: < 0.05 counts per sample. Adjusted Droop using droop fine trim DACs: < 0.007 counts per bin. Fine Trim DAC Gain: 0.5 with respect to offset difference from sample 0 to sample 315.

Interchannel Matching* (All four channels): Gain < 1% maximum, typical < 0.3%. Unadjusted Offset: < 15 counts; Adjusted Offset using offset fine trim DACs: < 2 counts. Fine Trim DAC Gain: 0.5.

Interchannel Isolation: 55 dB any A Channel to any B Channel; 48 dB Channel A1 to A2 and Channel B1 to B2 (at 40 MHz clock rate; better at lower clock rates).

Digitizing Time: Approximately 1.3 msec for Biphase 632 sample or Uniphase 316 sample conversion to digital memory. Correspondingly less for hardware programmed shorter record lengths.

Time Base: Front-panel switch. Selects the source of the sample clock. Internal or External.

Internal Clock: Crystal controlled oscillator operating at 80 MHz (equivalent to 40 MHz sampling in Uni-phase mode). Other oscillator crystals may be user installed.

CLOCK IN: NIM standard input via a Lemo connector. Impedance 50 ohm. Frequency range: 8 MHz to > 80 MHz. Minimum width 5 nsec. Every other negative going edge causes the sampling of the even numbered inputs. Alternate negative going edges sample the odd channels.

CLOCK OUT: NIM standard output via a Lemo connector. Impedance 50 ohm. Ungated representation of clock used to operate CCD channels in acquisition mode. May be used as monitor or as source for another 2262 CLK IN, to achieve matching of sampling rates. Propagation delay CLK IN to CLK OUT: 6 nsec typical.

TRIGGERING

Common Stop: NIM standard input via a Lemo connector. Impedance 50 ohm. Terminates acquisition mode on leading edge; begins data conversion on trailing edge. Width must be greater than 1 period of the acquisition clock or > 50 nsec; 100 µsec maximum.

Fast Clear: NIM standard input via a Lemo connector. Impedance 50 ohm. Terminates conversion in progress. Enables the unit for data acquisition; 50 nsec minimum width.

CAMAC Trigger Output: Front-panel NIM trigger output. Generates a NIM level of approximately 200 nsec duration upon

Connectors: All front-panel connectors are Lemo. Power: In general, power requirements decrease as clock rate is reduced. Examples are given below.

Packaging: In conformance with CAMAC standard for nuclear modules (ESONE Committee Report EUR4100 and/or IEEE-583). RF-shielded CAMAC #1 module.

Height: 221 mm; width: 17 mm; depth: 292 mm.

Voltage/Current Chart

Optional Crystal Oscillators Chart

CAMAC COMMANDS

CAMAC COMMANDS

C, Z: Same as F(9).

I: Inhibit Stops on all channels.

X: Indicates receipt of valid function code.

CAMAC FUNCTION CODES

F(0): Read last clock state.

F(2): Read data and advance memory pointer (subaddresses 0-7).

Subaddressing:

0 = channel A1 uniphase.
1 = channel A2 uniphase.
2 = channel B1 uniphase.
3 = channel B2 uniphase.
4,5 = channel A biphase.
6,7 = channel B biphase.

F(8): Test LAM.

F(9): Enables 2262 for data acquisition. Aborts data conversion if in progress. Disables Q Response until new conversion is completed. Clears LAM. Enables Stops.

F(10): Clears LAM.

F(16): Write DACs (subaddresses 0-7).

Subaddressing: 0-3 = pedestal adjustment DAC. Subaddress corresponds to uniphase channels as in F(2) above; 4-7 = RSO adjustment DAC. Subaddress corresponds to biphase channels as in F(2).

F(17): Write memory pointer.

F(19)·A(0): Generate CAMAC Trigger Out.

F(19)·A(1): Select Normal/Test Inputs (W1=0=normal, W1=1=test).

Note: The choice of test/normal inputs is NOT initialized on power up.

F(24): Disable (mask) LAM.

F(25): Generate a conversion cycle via an internally generated stop signal for test purposes (if stops are en abled).

F(26): Enable (unmask) LAM.


Copyright© September 1995. LeCroy is a registered trademark of LeCroy Corporation. All rights reserved. Information in this publicaction supersedes all earlier versions.