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! colspan="3" style="background:#ffdead; text-align:left" | Transistors
! colspan="3" style="background:#ffdead; text-align:left" | Transistors
|-
|-
| <math>VT_1</math> || E2P <small>(1717)</small> || Philips BFS 17A
| VT<sub>1</sub> || E2P <small>(1717)</small> || Philips BFS 17A
|-
|-
| <math>VT_2</math> || W1S <small>(13)</small> || Philips BFT 92
| VT<sub>2</sub> || W1S <small>(13)</small> || Philips BFT 92
|}
|}
:''Main article: [[MATLAB amplifier in detail]]''
:''Main article: [[MATLAB amplifier in detail]]''
We developed a model for this circuit in MATLAB to simulate its behavior and study various parameters, especially gain as a function of power voltage. The Photonique documentation claims that the power voltage can be varied between four and nine volts in order to tune the gain of the amplifier. The MATLAB model is a linearized system of twenty-four equations, with the voltages and currents on the circuit being the twenty-four unknowns. There are four input parameters: input current (<math>I_{in}</math>, in amps), the bias voltage (<math>V_b</math>, in volts), the power voltage (<math>V_c</math>, in volts), and the frequency (<math>f</math>, in hertz). The resistor values are mostly the same as the ones given for the above diagram, but some were changed to fit the model to actual data. We also add a load resistor from <math>V_{out}</math> to GND, with a value of <math>50\Omega</math>. The transistors are described by a series of parameters from the [http://en.wikipedia.org/wiki/Gummel-Poon_Model Gummel-Poon SPICE model], and we included our best guesses of the capacitor values.
We developed a model for this circuit in MATLAB to simulate its behavior and study various parameters, especially gain as a function of power voltage. The Photonique documentation claims that the power voltage can be varied between four and nine volts in order to tune the gain of the amplifier. The MATLAB model is a linearized system of twenty-four equations, with the voltages and currents on the circuit being the twenty-four unknowns. There are four input parameters: input current (I<sub>in</sub>, in amps), the bias voltage (V<sub>b</sub>, in volts), the power voltage (V<sub>c</sub>, in volts), and the frequency (f, in hertz). The resistor values are mostly the same as the ones given for the above diagram, but some were changed to fit the model to actual data. We also add a load resistor from V<sub>out</sub> to GND, with a value of 50Ω. The transistors are described by a series of parameters from the [http://en.wikipedia.org/wiki/Gummel-Poon_Model Gummel-Poon SPICE model], and we included our best guesses of the capacitor values.
The model itself can be found [http://zeus.phys.uconn.edu/halld/tagger/electronics/design-6-2007/SSPM_amp.zip here].
The model itself can be found [http://zeus.phys.uconn.edu/halld/tagger/electronics/design-6-2007/SSPM_amp.zip here].
== Responses of the model ==
== Responses of the model ==
We ran simulations of the MATLAB model while varying the input parameters to generate data on how the amplifier responds to each input. We used as a baseline test the inputs <math>V_b = 20\mbox{V}</math>, <math>V_c = 5\mbox{V}</math>, <math>f = 100\mbox{MHz}</math>, and <math>I_{in} = 1\mbox{mA}</math>, then varied one parameter at a time to generate responses.
We ran simulations of the MATLAB model while varying the input parameters to generate data on how the amplifier responds to each input. We used as a baseline test the inputs V<sub>b</sub> = 20V, V<sub>c</sub> = 5V, f = 100MHz, and I<sub>in</sub> = 1mA, then varied one parameter at a time to generate responses.
=== Bias voltage ===
=== Bias voltage ===
We varied the bias voltage from 0 to 50V. Within this range the output (<math>V_{out}</math>) does not vary at all.
We varied the bias voltage from 0 to 50V. Within this range the output (V<sub>out</sub>) does not vary at all.
=== Power voltage ===
=== Power voltage ===
The amplifier's response to varying the power voltage (<math>V_c</math>) from 0 to 10V is shown in the image below.
The amplifier's response to varying the power voltage (V<sub>c</sub>) from 0 to 10V is shown in the image below.
[[Image:Amplifier Response to Power (2007-07-03).png]]
[[Image:Amplifier Response to Power (2007-07-03).png]]
Note that the vertical axis can be read as either the output voltage (<math>V_{out}</math>) in mV or as the transimpedance gain in <math>\Omega</math>.
Note that the vertical axis can be read as either the output voltage (V<sub>out</sub>) in mV or as the transimpedance gain in Ω.
=== Frequency ===
=== Frequency ===
The amplifier's response to varying the frequency (<math>f</math>) is shown in the image below.
The amplifier's response to varying the frequency (f) is shown in the image below.
[[Image:Amplifier Response to Frequency (2007-07-03).png]]
[[Image:Amplifier Response to Frequency (2007-07-03).png]]
Note that the vertical axis can be read as either the output voltage (<math>V_{out}</math>) in mV or as the transimpedance gain in <math>\Omega</math>.
Note that the vertical axis can be read as either the output voltage (V<sub>out</sub>) in mV or as the transimpedance gain in Ω.
=== Input current ===
=== Input current ===
Varying the input current from 0 to 2A results in a clean straight line that intersects the origin. Thus we can say that the amplifier has a transimpedance gain (programmable based on input parameters; in particular <math>V_c</math>) and no DC bias.
Varying the input current from 0 to 2A results in a clean straight line that intersects the origin. Thus we can say that the amplifier has a transimpedance gain (programmable based on input parameters; in particular V<sub>c</sub>) and no DC bias.