11A34: Difference between revisions

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''

{{Spec | Rise time | 1.2 ns in 1 GHz mainframe such as the [[11402]], [[11402|11402A]], [[11403]], [[11403|11403A]], [[DSA600|DSA601A]], or [[DSA600|DSA602A]] }}

 

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

 

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

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.

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 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.

 

* [[11A-series plug-in NVRAM replacement]]

* [http://www.barrytech.com/tektronix/tek11000/tek11a34.html Tek 11A34 @ barrytech.com]

Tek 11a34 front.jpg | 11A34 front view