The Teledyne LeCroy AP033 is a wide band differential active probe. The probe features low noise, low input capacitance, high common mode rejection, and FET-buffered inputs in the probe head. User selectable attenuation and offset give the probe flexibility to measure a large range of signal amplitudes. Plug-on attenuator and AC coupling accessories further extend the application range. Interconnect accessories included allow connection to surface mount and through hole components with minimal signal degradation. The input receptacles in the probe head are compatible with standard 0.025 in. (0.635 mm) square pins, providing a convenient lowcost method of creating device characterization test fixtures.

The AP033 probe is powered directly from a Teledyne LeCroy oscilloscope through the ProBus® interface. The ProBus interface also allows local control of the probe through the oscilloscope user interface and remote control through the interface buses, (GPIB, RS232). The optional ADPPS power supply allows the AP033 to be used with other instruments such as spectrum analyzers, network analyzers, and oscilloscopes without ProBus interface.

The AP033 is ideal for acquiring high speed differential signals such as those found in disk drive read channels, differential LAN, video, etc. It can also be used with spectrum analyzers to acquire signals in some RF systems (for example, balanced IF mixers in hand held cellular telephones). The high impedance characteristics of both inputs allow the probe to be used as a FET probe to make single-ended measurements in digital systems without introducing a ground loop, as a conventional FET probe would.

Fully Integrated: With the ProBus™ interface, the AP033 becomes an integral part of the oscilloscope. The probe sensitivity and offset can be controlled from the oscilloscope front panel, the probe front panel, or by using remote control commands (GPIB or RS-232). Sensitivity, offset, input capacitance, and common mode voltage range are displayed on the oscilloscope screen. When used with a LeCroy digital oscilloscope, no external power supply is required.

Wide Dynamic Range: The AP033 provides a range of sensitivities from x10 gain to ÷10 attenuation (even ÷100 with plug-on attenuator) for diverse signals. The sensitivity can be adjusted continuously from 200 µV/div to 1 V/div, when used with a LeCroy oscilloscope.

At high sensitivities, the x10 GAIN and the ÷1 ATTENUATION are selected. This produces 4 nV/√Hz input noise, ±5 V of common mode voltage range (CMVR), and ±400 mV of DC differential offset. At lower sensitivities, the x1 GAIN and ÷10 ATTENUATION are selected, resulting in ±50 V CMVR and ±4 V of differential offset.

The input capacitance is just 2 pF/side (1 pF differential) whenever the ÷10 ATTENUATION is selected. Deflection factors of 2 mV/div to 1 V/div can be obtained with only 2 pF/side input capacitance and ±50 V CMVR.

DC CMRR is greater than 10,000:1 (80 dB) in both ATTENUATION settings.|OFFSET up/down buttons allow OFFSET control from the probe amplifier body. Momentarily holding both buttons will zero the OFFSET.

A supplied AC coupling capacitor head (0.1 µF) allows operation with large common mode or differential DC inputs.

The input attenuator automatically changes from ÷1 to ÷10 when too much common mode signal is sensed. This and a fast input protection circuit also serve to protect the input from potentially damaging signals. When the probe is removed from the oscilloscope or the power is turned off, the ÷10 ATTENUATION is automatically invoked, leaving the inputs protected when not in use.

Gain and Attenuation Selections

The AP033 consists of a probe head with ÷1 or ÷10 attenuation and an amplifier body which attaches to the scope front panel. The amplifier gain can be either x1 and x10. Both the probe head attenuator and amplifier gain are controlled through the ProBus interface. Normally the GAIN and ATTENUATION selections are accomplished by the oscilloscope.

There are two ways of obtaining x1 gain from the AP033: x1 GAIN with ÷1 ATTENUATION, or x10 GAIN with ÷10 ATTENUATION. The oscilloscope selects the latter of these two options to provide minimum input capacitance and maximum common-mode dynamic range while still leaving low noise operation available at the highest sensitivity.

By using the probe amplifier body control to override the automatic selection, the x1 GAIN with ÷1 ATTENUATION option is readily available for 10 mV, 20 mV and 50 mV/div. CMVR is ±5 V, input capacitance is 5 pF, and noise is 9 nV/√Hz. Similarly, x10 GAIN and ÷10 ATTENUATION can be selected at 2 mV/div and 5 mV/div for 2 pF input C and ±50 V CMVR. The oscilloscope displays the correct deflection factor in all cases.

Using the supplied accessory plug-on attenuator head, gain selections from 100 mV/div to 10 V/div are available.