TZA500
35Pages

Flexible Transimpedance Amplifier Gain and bandwidth control 6 gain ranges 4 bandwidths Production automation (e.g.: connectorization, pigtailing) Auto-null function Component testing, burn-in, lifetime Maximum input current Noise equivalent current (NEIRMS) Quality control MEASUREMENT PRINCIPLE The TZA500 series of amplifiers employs precision dual transimpedance input stages to provide for high common mode rejection and linearity throughout the full dynamic range. The differential input stage design requires a floating current input. If the application involves a grounded current source, a single ended amplifier must be used. FIELDS OF APPLICATION These transimpedance amplifiers are particularly useful for the measurement of current from photodiodes. The output is a voltage linearly proportional to input current and thus, to input power in photodiode monitoring applications. The fast response time at high signal-noiseratio makes this TZA series particularly useful in systems control feedback loops. The high sensitivity and large dynamic range allow measurement of a wide range of optical sources such as lasers and Artifex Engineering Dortmunder Str. 16-18 26723 Emden, Germany LEDs via a variety of photodiodes for these applications such as Si and InGaAs. The TZA500 series is insensitive to electromagnetic interference by design, an important factor when working in „dirty“ industrial environments. The proprietary auto-nulling function allows up to 10V of offset nulling. This is particularly useful for nulling dark current or for eliminating a DC signal component to concentrate on signal changes, such as in component burn-in and life-time testing. Differential Input mail: info@afx-eng.com http://www.afx-eng.com

ABSOLUTE MAXIMUM RATINGS Average Optical Power Temperature Range ORDERING INFORMATION Full order code: Differential Single Ended Case style: For example, a 2 channel, OEM style unit with single-ended input (for grounded photodiode measurement) would be ordered as: TZA500GSB2 For customized systems (eg: customized gain or receptacles or mixed amplifier systems), please contact us.

SPECIFICATIONS Parameter Input Current ranges (full scale) Noise equivalent current (NEIRMS) 0 (virtual short circuit) Output Function Output scale Linear analogue Vout = scale x Iin Range: Connectors Output range (full scale) Rise / Fall time (10% - 90%) Settling time (1%) Small signal (-1+1V) Large signal (-10+10V) Small signal (-1+1V) Large signal (-10+10V) Output impedance Logic Current required for switching (5V) Switching time Power Supply Type Wall plug (supplied) Adapters for other connector systems available upon request Logic switching < 1µs. Effective switching time limited by...

TYPICAL PERFORMANCE CURVES Linearity 0,20 0,15 APPLICATIONS EXAMPLES Typical applications may be found in measuring currents from photodiodes, photomultipliers, ionisation detectors, etc. with applications in component manufacture and testing, OEM, spectroscopy, as preamplifiers for lock-ins, A/D-converters, etc.

LINEAR OR LOGARITHMIC? The question often arises as to which signal processing technique is better: an output linearly or logarithmically proportional to the input optical power. The use of logarithmic amplifiers for optical power monitoring results from the large dynamic range of relevant powers. For example, the TZA500 series can measure from 10mA to 10pA: more than 7 decades of optical power. This dynamic range is far beyond the capabilities of a linear amplifier in a single gain range. However, by breaking the measurement into range subgroups, linear amplifiers can easily cover the same...

PRINCIPLES OF OPERATION The TZA500 measures small currents e.g. optical power via a photodiode. Photodiodes are useful for power measurement in the visible and near infra-red due to their inherent sensitivity and speed of measurement. Photodiodes produce a current which is proportional to the incident light power over a wide dynamic range. The current is converted to a voltage through a precise transimpedance amplifier. This amplifier is very linear over the full measurement range of the device. The TZA500 has 6 gain ranges. The switch is a semiconductor device, free from degradation. A...

AUTO-NULL The auto-null function sets the momentary output signal to zero. In this manner, a constant overlying signal such as a background illumination or detector dark current may be eliminated. Small signal changes may now be detected more readily. Note: the output signal must be positive in order to use this function! The auto-null is activated by a HI signal on pin 20 of the DB25 interface or by a command $A on the USB interface. The reset to normal operation is obtained with a HI on pin 19 of the DB25 interface or the command $R on the USB interface. The value of the removed portion...

BANDWIDTH REDUCTION The TZA500 has four selectable analogue bandwidth ranges. Reduction of bandwidth is useful for suppressing high frequency noise from slower signals. The full bandwidth of the amplifier is 10kHz. Using the bandwidth reduction, this may be reduced to 1kHz, 100Hz or 10Hz. The bit setting on the DB25 interface is as follows: Bandwidth INDICATORS The condition of the instrument is indicated through two LEDs: Power (LED, green): The input current is too high for the gain range chosen. The overload indicator works only for positive signals and indicates and output greater than...

INTERFACES HARDWIRE INTERFACE The hardwire interface (DB25 connector) is active upon starting the TZA500. This interface has two galvanically isolated grounds. The analogue ground (pin 3) is the reference point for the analogue signals (pin 6 and pin 25). The digital ground (pin 9) is the reference for all digital inputs and outputs. It is recommended to not connect these two grounds in order to avoid slight disturbances and glitches which may be present on the digital lines. The pinning of the DB25 interface is as follows: PIN Function AGND (ground for analogue signals) digital output: HI...