Time-to-Amplitude Converter (TAC)

Time-to-Amplitude Converter 2580

The time-to-amplitude converter (TAC) model 2580 measures the time interval between pulses to its start and stop inputs and generates an analog output pulse proportional to the measured time. The TAC can measure 50 ns to 2 ms times.  The following figure shows the TAC block diagram .Valid start and valid conversion outputs are provided for each accepted start and stop input, respectively. The duration of the valid start output indicates the interval from the accepted start signal until the end of reset. The valid conversion output occurs from the end of the internal delay after stop to the end of reset.

 

Specifications

Performance

• Time resolution: FWHM ≤ 0.01% of full scale plus 5 ps for all ranges
• Temperature instability: ≤±0.01%/°C (±100 ppm/°C) of full scale or ±10 ps/°C (whichever is greater), 0 to 50 °C.
• Differential nonlinearity: ±1% ≥ from 10 ns or 2% of full scale (whichever is greater) to 100% of full scale.
• Integral nonlinearity: ±1% ≥ from 10 ns or 2% of full scale (whichever is greater) to 100% of full scale.
• Reset cycle: Fixed 1.0 µs for X1 and X10 multipliers, fixed 5 µs for X100 multiplier, and fixed 50 µs for X1 K, and X10 K multipliers. Occurs after over range, strobe cycle, or Ext strobe reset cycle.
• Start-stop conversion time: Minimum ≤5 ns.

 

Controls

• Range (ns): Three-position rotary switch selects full scale time interval of 50, 100, or 200 ns between accepted start and stop input signals.
• Multiplier five-position rotary switch extends time range by a multiplying factor of 1, 10, 100, 1K, or 10K.
• Delay: 20-turn screwdriver adjustable potentiometer varies the delay of the TAC output from 0.5 µs to 10.5 µs, relative to an accepted stop input signal; operable in the Int strobe mode only.
• Strobe mode: Two-position locking toggle switch selects either internal or external source for initiating the strobe cycle to strobe valid information from the TAC output.
• Gate Mode: Two-position locking toggle switch selects coincidence or anticoincidence mode of operation for the Start circuitry. Start circuitry is enabled in the Coinc position or inhibited in the anti-position during the interval of a gate input signal.
• LOG current: Two-position locking toggle switch selects the use of ±6 V or ±12 V bin lines to provide current for the internal logic circuitry.

 

INPUTS

• All four inputs listed below are dc-coupled, edge triggered and printed wiring board (PWB) jumper selectable to accept either negative or positive NIM standard signals. Input impedance is 50 Ω in the negative position and >1 kΩ in the positive position. The threshold is nominally 400 mV in the negative position and +2 V in the positive position.
• Strobe: Front-panel BNC connector provides an external means to strobe a valid output signal from the TAC in the Ext strobe mode. The input signal, exceeding threshold within the Ext strobe reset interval after the stop input, initiates the read cycle for the linear gate to the TAC output. Factory-set in the negative input position. Ext strobe reset interval has a minimum value of ~0.5 µs and a maximum value of nominally 10 µs.
• Start: Front-panel BNC connector initiates time conversion when start input signal exceeds threshold. Factory-set in the negative input position.
• Stop: Front-panel BNC connector terminates time conversion when stop input signal exceeds threshold. Factory-set in the negative input position.
• Gate: It in BNC connector provides an external means of gating the start circuitry in anticoincidence with the start input signal. Gate input signal must cross threshold ≥10 ns prior to the start input signal and must overlap the trigger edge of the start input signal. Factory-set in the positive input negative.

 

Outputs

TAC Output

• Front-panel BNC connector provides unipolar pulse.
• Amplitude: 0 V to +10 V proportional to Start/Stop input time difference.
• Time: End of delay period in Int strobe mode; prompt with strobe input in Ext strobe mode.
• Width: Adjustable by PWB potentiometer from ≤1 µs to ≥3 µs.
• Impedance Zo <1 Ω.
• Rise Time: ~250 ns.
•  Fall Time: ~250 ns.

VAL ST

• Rear-panel BNC connector provides NIM-standard slow positive logic level signal.
• Amplitude: Nominally +5 V. Complement signal selectable by PWB jumper.
• Time and Width: From accepted start input to end of reset.
• Impedance: Zo <10 Ω.
• Rise Time: ≤50 ns.
• Fall Time: ≤50 ns.

VALID CONV

• Rear-panel connector provides NIM-standard slow positive logic level signal to indicate a valid conversion.
• Amplitude: Nominally +5 V. Complement signal selectable by PWB jumper.
• Time and Width: From end of internal delay after stop to end of reset.
• Impedance:  Zo <10 Ω.
• Rise Time:  250 ns.
• Fall Time:  250  ns.

 

Power Requirement (Logic Switch)

Power required in Log current mode for ± 6 V

+24 V	35 mA
-24 V	50 mA
+12 V	70 mA
-12 V	105 mA
+6 V	140 mA
-6 V	300 mA

 

Power required in Log current mode for ± 12 V

+24 V	35 mA
-24 V	50 mA
+12 V	210 mA
-12 V	405 mA

 

Installation Requirements 

• Laboratory
• A table for placing instrument
• Bin power supply model 8000 or 8010
• Pulse generator
• Discriminator
• Delay and gate generator
• Nano-second delay
• Photomultiplier tube
• BNC cable
• Amplifier
• Multichannel buffer
• Amplifier and preamplifier
• The equipped room with an air conditioning for constant temperature and humidity
• Power
• Oscilloscope

 

Long Term Warranty And After Sales Service