11A34

Manuals – Specifications – Links – Pictures

The Tektronix 11A34 is a four-channel vertical amplifier plug-in for 11000-series and DSA600-series scopes.

Option 23 added four P6134 probes.

There is also a version for video applications, the 11A34V, that was introduced in 1991 (see also 11T5H). It differs from the 11A34 only in its input impedance (75 ohms). Development of the 11A34V was managed by Murlan Kaufman.

more information about 11A34V needed

Key Specifications

Bandwidth	DC to 300 MHz. 100 MHz and 20 MHz four pole BWL (Bandwidth Limit) filters may be selected.
Rise time	1.2 ns in 1 GHz mainframe such as the 11402, 11402A, 11403, 11403A, DSA601A, or DSA602A
Deflection	1 mV to 10 V/div in 1% calibrated steps
Input impedance	50 Ω or 1 MΩ
Features	High-resolution calibrated DC offset Fast overdrive recovery 5 VRMS input overload protection in 50 Ω mode, with manual reset

Links

• 11A-series plug-in NVRAM replacement
• Tek 11A34 @ barrytech.com

Internals

Analog

Each input channel has a separate attenuator module containing passive 1 megohm attenuators, an AC coupling capacitor, a switch selecting the calibrator or signal input and an M474 buffer amplifier. The calibrator signal turned off inside the plugin when not in use.

The attenuator module output feeds the + input of the M377 amplifier IC through a (blue) 50 ohm transmission line, one per input channel. The cable lengths set a standard delay per plugin.

The M377's - input is connected to the ACVS (Analog Control Voltage System) output.

The (differential) display outputs of the four amplifiers are hard-wired in parallel and drive the mainframe’s 50 Ω per side input impedance. The same is true of the trigger outputs of the four amplifiers.

The version of the M377 used in the 11A34 has a 200 Ω output impedance per side so that four of them in parallel create a source impedance of 50 Ω.

Each M377 amplifier's nominal common-mode output voltage is zero whether enabled or not. When not enabled, each M377 differential output is exactly zero by design. This fact is used during calibration by the plugin’s firmware to determine the mainframe’s imbalance and compensate for it during normal operation.

Each of the four channels has its own AUX output on dedicated pins of the plug-in interface connector:

signal name	positive pin number	negative pin number
AUX 1	B38	B37
AUX 2	A36	A35
AUX 3	B32	B33
AUX 4	A32	A31

The AUX signals emerge from each M377 amplifier as differential signal with a 200 Ω source impedance per side. External (on the circuit board) 66.5 Ω shunt resistors on each AUX output bring this down to the 50 Ω source impedance specified by the 11k plug-in interface.

See also the block diagram below.

Digital

The 11A34 and the 11A32 use exactly the same firmware.

The 11A32 and 11A34 were originally intended to use Intel 8052 microcontrollers. However, during development, the firmware swelled beyond that chip's 8192-byte maximum on-chip ROM size. Doug Haines found an alternate supplier of 8051-compatible chips (OKI Semiconductor) that offered a 16Kbyte on-chip ROM, and that's what the plug-ins wound up with. The finished code size wound up at about 14 KB.

The 11A34 also contains a Dallas Semiconductor DS1220Y NVRAM storing last settings, calibration constants, and instrument serial number. The DS1220Y contains a battery with a typical life time of 20-30 years.

There are also two ACVS (Analog Control Voltage System) sample and hold modules on two daughter boards that generate the analog voltages needed for gain and offset, including error correction under microcontroller firmware control.

The microcontroller also provides the digital signals sent to the M377 amplifier, setting one of its six fixed gains, one of its three bandwidths, turning on or off its selected output, and each output's + up or invert state.

Digital mainframes do waveform manipulation (addition, subtraction, multiplication, etc.). Consequently only one 11A34 output is on at a time. Analog mainframes however allow more than one channel to be on at a time. This allows the plugin channels to be added or subtracted in the plugin.

Pictures

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  11A34 front view

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  front view

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  left side view

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  right side view

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  bottom view

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  Block diagram

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  Analog Control and Signal Amplifiers

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  11A34V and 11T5H

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  11A34V and 11T5H

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  Prototype 11A34

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  Prototype 11A34

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  Prototype 11A34

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  Prototype 11A34

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  11A34V front

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  11A34V rear

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  11A34V left internal

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  11A34V right internal

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  11A34

Custom ICs used in the 11A34