DESCRIPTION
The Model 8089 Digitally Programmable Amplifier has pendent of gain. At room temperature the offset is less
been designed for precision amplification applications than _ one millivolt and remains less than 10 millivolts
where low output dc offset is critical. The Modei 8089 is even at 200 degrees CIThis performance permits the am-
ldeally suited to amplifying low level geophone signals plifier to be directly coupled to a low impedance ouput
and driving the signal cabie directly. The Model 8089 transformer winding and maintain alow standby current.
is well suited to applications in high temperatureenviron- The input stage is a high input impedance voltage fol-
ments such as found in oil wells and jet engine controls. lower operationalamplifier equipped with an input clamp
The Model 8089 features the ability to quickly change circuit to prevent damage in the presence of voltage
gain to one of four precision values ranging from 12 to spikes and overvoltage conditions,Such overvoltages
48dB. The gains are held to :2% initially and feature a may occur when geophones and other high outputtrans-
very low drift with temperature change. An overall high ducers are strongly excited.
power gain is achieved by providing a very high input The Model 8089 consumes a modest current of 15mA
impedance of over 10 Megohms and a low output im- at 土 15Vdc and the program inputs will interface with
pedance of less than 10 ohms: 5V logic inputs. The response time to gain changes is
The module is equipped withan outputdriverstagethat nearly instantaneous. The module is constructed with
is capable of driving a 50 ohm load with a 24 volt peak to specially configured high temperature thick film tech-
peak signal, The output stage is protected against short nology to meetthedemanding temperatureand mechani-
circuits, Further,the design of the 8089 provides for cal environmental needs common to oil logging and
a very low output dc offset voltage that is virtually inde- similar applications.