Front Panel

Absolute Maximum Ratings

The absolute maximum ratings for the front panel controls are listed below:

• Digital Input Forward Current: 15 mA.
• Digital Input Reverse Voltage: 5 V.
• Analog Input Voltage: |V_ext| < 25 V.
• VCO Ctl Voltage: 0 V <= 3*(V_ext + V_int) < V_max.
  • Here, V_max is the absolute maximum rating of the frequency tuning pin on the AOM driver's VCO. You should confirm the maximum rating for the VCO installed on your driver!
• Atten Ctl Voltage: 0 V <= V_ext/3 + V_int < 4 V.
• Aux. RF In Power: 10 dBm.
• RF Out VSWR: 6:1.
  • If you don't know what this means, look it up.

Amplifier Power Switch

The Amplifier Power Switch activates the power sequencers that safely turn on/off the RF pre-amplifier and RF power amplifier. This switch must not be turned on without a 50 Ohm load connected to RF Out! When powering up the AOM Driver, this switch should be in the off position. When powering down the AOM driver, this switch should be turned off 2 seconds before the rear power switch is turned off.

TTL Inputs

All TTL inputs are opto-coupled with a TLP2767. The TLP2767 has a propagation delay < 20 ns and a rise/fall time < 2 ns. The TTL inputs are compatible with both 3.3 V and 5 V signals. Your digital voltage source must be able to drive 5 mA (10 mA) for 3.3 V (5 V) signaling. All digital inputs are inverting!

Aux TTL

The Aux Trigger is connected to the driver's microcontroller. In the current code version (d60202a), this input is not used. Future code versions may include a tabled control mode where the microcontroller adjusts VCO voltage, attenuator voltage, or DDS frequency through a set of pre-programmed values. The Aux Trigger would control the rate at which the microcontroller steps through the table.

RF Select

The RF select TTL switches the RF source that is fed into the RF pre-amplifier. Input low selects the VCO and input high selects Aux. RF In. This TTL input only operates when the RF select switch is set to the "Ext" position.

RF Output Ctl

The RF Output Ctl TTL controls two RF switches to turn on (input low) or off (input high) the RF output to the power amplifier. This TTL input only operates when the On/Off switch is set to the "Ext" position.

Analog Inputs

Both analog inputs are differentially sensed by an AD8421 instrumentation amplifier. A 50 Ohm resistor provides ground isolation. The bandwidth of the instrumentation amplifier is 10 MHz, but the FM and AM bandwidths of the driver are limited by the VCO and VVA, respectively.

VCO Ctl

The VCO Ctl input is a non-inverting input with a gain of 3 and an impedance of 10 kOhm. This input can be used to set the VCO operating frequency. The VCO Ctl input is only active when the VCO Ctl switch is in the "Ext" or "Ext + Int" positions. The absolute maximum rating of the VCO frequency tuning pin depends on the VCO model (Typically, V_max > 15 V for Minicircuits VCOs). You must ensure that 0 V <= 3*(V_ext + V_int) < V_max. V_int is displayed in the VCO Voltage sub-menu on the LCD display.

Atten Ctl

The Atten. Control input is a non-inverting input with an impedance of 10 kOhm. This input can be used to change the power output of the AOM driver. It is only active when the attenuator control switch is in the "Ext" or "Ext + Int" positions. The voltage applied to this input is divided by 3 before being applied to the attenuator control pin. The absolute maximum rating for the attenuator control pin is 4 V. Therefore, you must ensure that 0 V <= V_ext/3 + V_int < 4 V. V_int is displayed in the Atten. Voltage sub-menu on the LCD display.

RF Inputs

Aux. RF In

Attach an auxiliary RF source here. This input is fed to the pre-amplifier and power amplifier when the RF select switch is in the "Aux RF" position.

RF Outputs

RF Mon

RF Mon is the output of the low power tap of a 20 dB directional coupler. There is only RF power present at RF Mon when the RF Output Ctl switch is turned on (or is turned on using TTL).

RF Out

The main output of the AOM driver. Do not turn on the Amplifier Power switch without a 50 Ohm load connected to RF Out! Note that, for RF source frequencies from 10 MHz to 100 MHz, there can be > 5 W present at RF out, which may be sufficient to destroy low power acousto-optical and electro-optical devices.

Aux RF 2

Aux RF 2 is not connected internally. It is intended to be used if user customization of the driver is necessary.